DE19530770A1 - Zoom lens system for self-focussing photographic or video camera - Google Patents

Abstract

The system has movement settings (g1-g4) of the four lens units (G1-G4) along the optical axis for zooming purposes. They are defined by synthesis of a focussing curve and a zoom compensation curve in accordance with state formulae relating the rotation of the objective lens drum to the distance travelled from a wide-angle to a telephoto final position. Alternatively it incorporates two positive (convex) and two negative (concave) lens units. Focal lengths, intervals between points of symmetry, numerical data for the two curves, and rotary/linear movement conversion coeffts. are tabulated for them.

Description

Background of the Invention Field of the invention

The present invention relates to a zoom lens or a lens with ver variable focal length and in particular on a zoom lens that is attached to a so-called called auto-focusing camera, video camera, or the like attached has a focus detection device and a focusing Ob lens system in a photographing optical system according to the defo determined kissing amount moved.

Related Prior Art

In recent years, along with widespread use of autofocusing cameras different focusing systems, such as the inner focusing system, the rear focusing system, and the like, been checked to make a focusing lens compact with a zoom lens shape.

However, it changes generally when a focusing system is not one called front focusing system is taken, the lens drive contributes to focusing by changing the focus length or focal length. To this pro Japanese patent application no. 4-293008 and 5-142475, assigned to the assignee of the present invention  are a process for realizing a so-called manual, focusing pre first in a zoom lens that has a variety of lens units finally, a focusing lens unit that has both zooming or focal lengths has changing and focusing functions. In this process, when a predetermined moving point for zooming by the amount of a move tion of the lens units in the direction of the optical axis and by the rotation angle of a rotatable lens drum, the point of movement of the focus lens unit by synthesizing a focus cam and a zoom Compensation cam defined. With this arrangement, even if the Movement amount for focusing along the optical axis depending on the zooming state changes, the angle of rotation of the rotatable lens drum to Fo kissing unchanged, whereby a manual focusing process is carried out.

However, if the above zoom lens is used in an auto-focus renden camera system is applied, the focus or focal point determination device, a storage device for storing the conversion coefficient γ and the correction coefficient ε, which are used to calculate the lens drive amount Δx Focusing the focusing lens unit on the basis of the defocus determined sation amount ΔBf of a photographic optical system can be used, and a calculation device for calculating the lens drive amount Δx to Fo kiss using the defocus amount ΔBf, the conversion coefficient efficient γ and the correction coefficient ε, problems arise that the Spei capacity, to which calculation errors and the like are assigned.

As in Japanese Patent Application Laid-Open No. 4-293008 and 5-142475 mentioned above are in a zoom lens such as the japani published patent applications No. 57-37307, 57-37308, 63-49715, 63-314511, 3-144411, 3-235908, 3-249717, 4-184402, 4-184403.4-184404, 4-184405, 4-184406, 4-186207, 4-186208 and the like, in which the Bewe of the focusing lens unit by synthesizing a focus noc kens and a zoom compensation cam is set, the above problems such as memory capacity, calculation error, and the like concern, have not been checked or taken into account.  

Furthermore, zoom lenses such as those disclosed in Japanese Pa tent registrations No. 57-4018, 58-137812, 58-137814, 58-144808, 58-149014, 58-150925 and the like are disclosed, each of which has only one focus cam uses the problems of memory capacity, calculation error and the like have not been checked or taken into account.

On the other hand, in Japanese Patent Application Laid-Open No. 63-163808, 1-154014 and the like assigned to the holder of the present invention are transferred with zoom lenses, such as those disclosed in the Japanese Pa tent registrations No. 64-35515, 64-35516, 4-140704 and the like are disclosed, each of which conventionally has a single cam for both a focus cam used as well as a zoom cam, the problems of the above Storage capacity, the calculation error, and the like have not been checked. To In addition, the zoom lenses disclosed in these documents have a basis structure that is different from that of the present invention in that it do not require any zoom compensation cam and not the so-called consider flexible, manual focusing that is used in Japanese, published patent applications 4-293008, 5-142475 and the like checked or has been taken into account.

A zoom lens disclosed in Japanese Patent Application Laid-Open No. 2-256011, 3-101707 and the like disclosed to the holder of the present Invention are transferred, has a basic structure that compared to that of the previous lying invention is different because it is a zoom by a relative movement tion in the direction of rotation of a lens drum between a focus cam and egg a zoom cam and a focus through a relative movement in the rich Realization of the optical axis and not an auto-focusing device at all checks or takes into account.

Furthermore, Japanese Patent Application Laid-Open No. 61-77027, 1-232313 and the like a lens system that has a focus cam has an accurate auto-focusing process with a small calculation implementation errors. However, these writings refer to  Single focus or fixed focal length lens that has no zoom function, and they cannot be applied to a focus cam that is required to to obtain a so-called manual focusing process in a zoom lens at which the amount of movement in the direction of the optical axis for a Focus changes depending on the zooming state.

The principle of the auto-focusing process is briefly described below will.

An auto-focusing system disclosed in Japanese Patent Application Laid-Open dung No. 62-78519, 62-170924, 1-131507, 1-131508, 1-131509, 3-228006 and the same is disclosed, has a focus determining device, a calculation device device for calculating the lens drive amount for focusing and a storage chereinrichtung for storing specific constants that ver be spent on. In this system, the focus determination device determines the Defocus amount ΔBf between the imaging position of an actual Ob project by the photographing optical system and a predetermined image point position and the calculation device for calculating the lens drive Increments for focusing calculates the lens drive amount Δx for focusing the basis of the determined defocus amount ΔBf of the photographing optical Systems in order to achieve an auto-focusing operation.

If the ratio between the lens drive amount .DELTA.x to focus and the Defocus amount ΔBf using a conversion coefficient K that is assigned to the focus as follows:

Δx = ΔBf / K

then the lens driving amount Δx can be adjusted by setting the conversion coefficient K be calculated.

However, how this changes in Japanese Patent Application Laid-Open No. 62-170924, the conversion coefficient K does not only correspond to the Focal length, but also with the object position and the lens arrangement.  

Therefore, as shown in Japanese Patent Application Laid-Open No. 62-78519, 62-170924 and the like using the Conversion coefficient γ, which is the ratio (sensitivity) of the amount of an infini tesimal movement of the imaging plane with respect to the amount of an infinitesimal Movement of the focusing lens or lens unit near a vorbe is defined point in the focal point, and the correction coefficient ε to Kor correction of the conversion coefficient according to the defocus amount ΔBf, the Kon version coefficient K calculated using the following formulas:

K = γ + ε · f (ΔBf),
K = γ + ε · ΔBf² in Japanese Patent Application Laid-Open No. 62-78519
K = γ (1 + ε · ΔBf) in Japanese Patent Application Laid-Open No. 62-170924

and then the lens drive amount Δx is based on the Conversion coefficient K calculated.

(Of course, the lens drive amount Δx can be focused directly from the defocus sation amount ΔBf using the conversion coefficient γ and the correction coefficient ε can be calculated.)

Furthermore, in a photographing system that has a zooming, optical system stem has, since the values of the conversion coefficient γ and the correction coefficient change ε depending on the lens or lens arrangement, a plurality of data pairs of the conversion coefficient γ and the correction coefficient ε in the storage device in units of a plurality of divided zoom areas and Fo kus areas stored, as in the Japanese Patent Application Laid-Open No. 3-228006.

In other words, in the photographic system that determines the zooming, opti cal system, the focus determining device has the defocus amount ΔBf,  which is caused by the zooming optical system and values of the conversion coefficients γ and the correction coefficient ε, each of the zoom and focus positions tion correspond to that by the zoom and focus position determination device are averaged are read from the memory device. The calculation device The device for calculating the lens drive amount for focusing calculates the line Sen drive amount Δx for focusing using the defocus amount ΔBf, the conversion coefficient γ and the correction coefficient ε, and the An drive device drives a lens by the calculated lens drive amount Δx to Fo kissing, which consequently achieves a focusing process.

However, in a normal, focusing mechanism, one must screw shaped mechanism or a cam mechanism used, the lens drive amount for focusing not as a lens driving amount Δx in the direction of the opti rule, but as a lens drive amount Δa in the Direction of rotation.

Therefore, when the relationship between the lens drive amount Δx and the defocus amount ΔBf in the optical axis direction is in the relationship between the lens drive amount Δa and the defocus amount ΔBf in the rotation direction, using a conversion coefficient K _{a associated with} the rotation direction is:

Δa = ΔBf / K _a

If the conversion coefficient K associated with the direction of the optical axis is redefined as K _x , the conversion coefficient K _a associated with the direction of rotation is determined using a conversion coefficient Φ between the lens driving amount Δx in the direction of the optical axis and the lens drive amount Δa in the rotation direction is expressed as follows

K _a = K _x · Φ

Accordingly, the formula is disclosed in Japanese Patent Application Laid-Open No. 62-170924 modified to a formula which is assigned to the conversion coefficient K _a in the direction of rotation, as follows:

K _a = Φγ (1 + ε · ΔBf)

If there is a linear relationship between Δx and Δa similar to a helical one Mechanism exists, Φ becomes a constant. However, when a cam changes mechanism is used, the conversion coefficient Φ depending on the Cam shape. The conversion coefficient Φ can be replaced by a slope (dx / da) defined by the cam shape as follows

K _a = γ · (dx / da) (1 + ε · ΔBf)

The conversion coefficient γ and the correction coefficient ε in a zoom lens of the internally focusing type disclosed in Japanese Patent Application Laid-Open gen No. 4-293008, 5-142475 and the like is examined below will.

When a zoom lens system is constituted by n lens units and its kth lens unit is used as the focusing lens unit, if the ratio of the amount dBf of an infinitesimal movement of the imaging plane to the amount dx of the infinitesimal movement in the direction of the optical axis of the focusing lens unit, ie, the conversion coefficient γ (dBf / dx: the sensitivity associated with the movement in the direction of the optical axis) is defined as a new conversion coefficient γ _x , which is the amount x of movement in the direction of the optical axis If the axis is assigned, the conversion coefficient γ _x can be expressed as follows using the image magnifications β of the respective lens units:

γ _x = (1 - β _k ²) β _{k + 1} ²β _{k + 2} ². . . β _n ²

Therefore, the rate of change from the infinite focus in focus (γ _xO ) to the closest focus in focus (γ _xR ) of the conversion coefficient γ _{x associated with} the amount x of movement in the direction of the optical axis is, using the magnifications β _Ok and β _{Rk of} the focusing lens unit at the infinite and the closest point in focus, expressed as follows:

γ _xR / γ _xO = (1 - β _Rk ²) / (1 - β _Ok ²)

Furthermore, if the ratio of the amount dBf of an infinitesimal movement of the imaging plane to the angle da of an infinitesimal rotation of the focusing lens unit (dBf / da: the sensitivity associated with movement in the direction of rotation) can be defined as a new conversion coefficient γ _a , which is associated with the angle a of a rotation of a rotatable lens or lens drum, the conversion coefficient γ _a , which is associated with the angle of rotation of the rotatable lens or lens drum, can be expressed by:

γ _a = γ _x · (dx / da)

where dx / da is the slope of the focus cam.

Therefore, the rate of change, from the infinite focus in focus (γ _aO ) to the closest focus in focus or near focus setting (γ _aR ) of the conversion coefficient (γ _a ), which corresponds to the rotation _angle a is assigned to the rotatable lens drum, using slopes (dx / da) _O and (dx / da) _R at the infinite and the closest corresponding position on the focus cam, as follows:

γ _aR / γ _aO = (γ _xR / γ _xO ) ((dx / da) _R / (dx / da) _O )

The rate of change of the conversion coefficient γ _x with respect to the amount x of a movement in the direction of the optical axis and the rate of change of the conversion coefficient γ _a with respect to the angle a of a rotation of the rotatable objective lens is described below in connection with an embodiment of the Japanese patent application no. 5-142475 checked. Note that the amount of rotation for zooming from the wide-angle end to the telephoto end and the amount of rotation for focusing are each reset to 10.0 for the purpose of comparison with an embodiment of the present invention.

Table 1 below summarizes various paraxial or focal point data optical system and data for determining the shape of the focus cam correspond according to the embodiment of Japanese Patent Application Laid-Open No. 5-142475 together.

The upper table in Table 1 summarizes the length and focus data in principle Point interval data of the respective lens units of the optical system accordingly the embodiment of Japanese Patent Application Laid-Open No. 5-142475 together. In this table, F1, F2, F3 and F4 are the focus lengths and Focal lengths of the first, second, third and fourth lens units and D1, D2, D3 and D4 are each the main point interval between the first and second lenses nich, the main point interval between the second and the third lens unit, the Main point interval between the third and fourth lens units and the main point interval between the fourth lens unit and a predetermined image level in six zooming states (focal lengths F = 36.0, 50.0, 60.0, 70.0, 85.0 and 103.0 mm).

The middle table in Table 1 summarizes spline sample point data together when the shape of the focus cam in the second lens unit leading to the Fo kissing is used, is expressed by a spline function, the the angle a of a rotation of the rotatable lens barrel and the amount x of Movement in the direction of the optical axis is expressed (according to "Numerical Analysis and FORTRAN ", MARUZEN," Spline Function and Its Applications ", Kyoiku Shuppan, and the like).

Furthermore, the lower table in Table 1 summarizes the infinite, focusing positions (positions corresponding to the infinity setting) at the respective focus lengths (F = 36.0, 50.0, 60.0, 70.0, 85.0 and 103.0 mm) and the amounts of a rotation (amounts one Rotation for focusing) focusing on the respective photographing distances (R = 5.0, 3.0, 2.0, 1.5, 1.0 and 0.85 m) using the focus cam. Because both the amount of rotation for zooming for the wide-angle end (F = 36.0) to the telephoto end (F = 103.0) and the amount of rotation for focusing from the infinite position in focus to the closest position in focus (R = 0.85 m) are 10.0, the rotation amount ratio (a _F / a _Z ) of the rotation amount for focusing to the amount of rotation for zooming is 1.0.

Table 1

Data of an embodiment of Japanese Patent Application Laid-Open No. 5-142475 (rotation amount ratio: a _F / a _Z = 1.0)

Focus lengths and symmetry point intervals of the lens units of the embodiment of the Japanese laid-open patent application No. 5-142475

Focus cam shape (wedge interpolation) according to the embodiment of Japanese Patent Application Laid-Open No. 5-142475

Rotation amount for zooming and amount of rotation for focusing the embodiment of Japanese Patent Application No. 5-142475 (rotation amount ratio: a _F / a _Z = 1.0)

Table 2 below summarizes the numerical data values of the focusing cam Lens unit in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 together, the data by interpolation based on a wedge Function are calculated based on the scan data of the focus cam, which in the middle table in Table 1 are given. In this table ("ANGLE") is the Rota tion angle of the rotatable lens or lens drum, (2) is the amount (mm) of the loading movement in the direction of the optical axis of the second lens unit and (F) is the Focal length (mm) of the entire system in an infinite one in focus State corresponding to the amount (ANGLE) of a rotation.  

Table 2

Numerical cam value data of the focusing lens unit of the embodiment of Japanese Patent Application Laid-Open No. 5-142475

The left table in Table 2 summarizes the numerical data values of the focus cam the embodiment of Japanese Patent Application Laid-Open No. 5-142475 together and the right table in Table 2 summarizes the numerical data values of the Zoom compensation cam of the embodiment together. A value by Synthesize the amount (2) in one movement in the direction of the optical axis for the numerical data values of the focus cam and the numerical data values th of the zoom compensation cam in a range of the amount of rotation (ANGLE = 0.0) on the amount of a rotation (ANGLE = 10.0) is correct the movement point of the second lens unit, which using the pa radial data in the upper table in Table 1 are calculated.

Tables 3, 4 and 5 below summarize the amount DX (mm) of a movement for focusing in the direction of the optical axis of the focusing lens unit, the magnifications β _{k of} the respective lens units, the conversion coefficient γ _x , which is assigned to the direction of the optical axis is the slope (dx / da) of the focus cam and the conversion coefficient γ _a , which is assigned to the direction of rotation under the wide-angle end position (F = 36.0), the middle position (F = 50.0) and the telephoto end position (F = 103.0) is together. In these tables, (R) on the left is the photographing distance (m), (ANG) is the amount of rotation on the focus cam focusing on the respective photographing distances and 1), 2), 3) and 4) the right, represent the first, the second, the third and the fourth lens unit. Also in these tables, the first table summarizes the amount DX (mm) of a movement for focusing in the direction of the optical axis while focusing on the respective Photographing distances (R = 10.0, 5.0, 3.0, 2.0,1.5,1.0 and 0.85 m) together (note that the movement to the object side is positive). The second table summarizes the magnifications β _{K of} the respective lens units in a state in focus at the respective photographing distances (R = 10.0, 5.0, 3.0, 2.0, 1.5, 1.0 and 0.85 m). The third table summarizes the conversion coefficient γ _x , the direction of the optical axis of the focussing lens unit in a state in focus at the respective photography distances (R = 10.0, 5.0, 3.0, 2.0, 1.5, 1.0 and 0.85 m ) assigned. The fourth table further summarizes the slope (dx / da) of the focus cam at the positions on the focus cam, corresponding to a state in focus at the respective photographing distances (R = 10.0, 5.0, 3.0, 2.0.1.5 , 1.0 and 0.85 m), and the fifth table summarizes the conversion coefficient γ _a , which corresponds to the direction of rotation of the focusing lens unit in a state in focus at the respective photographing distances (R = 10.0, 5.0, 3.0, 2.0, 1.5, 1.0 and 0.85 m) is assigned.

Table 3

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the wide-angle end position (36.0 mm) in Japanese Patent Application Laid-Open No. 5-142475

Image magnification β _{K of} the lens units at the wide-angle end position (36.0 mm) in Japanese Patent Application Laid-Open No. 5-142475

Conversion coefficient γ _x , which is the direction of the optical axis at the wide-angle end position (36.0 mm) in Japanese Patent Application Laid-Open No. 5-142475 is assigned

Slope dx / da of a focus cam at the wide-angle end position (36.0 mm) in Japanese Patent Application Laid-Open No. 5-142475

Conversion coefficient γ _a , which is the direction of rotation at the wide-angle end position (36.0 mm) in Japanese Patent Application Laid-Open No. 5-142475 is assigned

Table 4

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the center position (50.0 mm) in Japanese Patent Application Laid-Open No. 5-142475

Magnification β _{K of} the lens units at the central position (50.0 mm) in Japanese Patent Application Laid-Open No. 5-142475

Conversion coefficient γ _x , which is the direction of the optical axis at the center position (50.0 mm) in Japanese Patent Application Laid-Open No. 5-142475 is assigned

Slope dx / da of a focus cam at the central position (50.0 mm) in Japanese Patent Application Laid-Open No. 5-142475

Conversion coefficient γ _a , which is the direction of rotation at the center position (50.0 mm) in Japanese Patent Application Laid-Open No. 5-142475 is assigned

Table 5

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the telephoto end position (103.0 mm) in Japanese Patent Application Laid-Open No. 5-142475

Magnification β _{K of} the lens units at the telephoto end position (103.0 mm) in Japanese Patent Application Laid-Open No. 5-142475

Conversion coefficient γ _x , which is the direction of the optical axis at the telephoto end position (103.0 mm) in Japanese Patent Application Laid-Open No. 5-142475 is assigned

Slope dx / da of a focus cam at the telephoto end position (103.0 mm) in Japanese patent application No. 5-142475

Conversion coefficient γ _a , which corresponds to the direction of rotation at the telephoto end position (103.0 mm) in Japanese Patent Application Laid-Open No. 5-142475 is assigned

As can be seen from Tables 3, 4 and 5, the conversion coefficient γ _x , which is assigned to the direction of the optical axis, and the slope (dx / da) of the focus cam increase at the respective focal lengths, if the Photo graphing distance closer to the closest distance. Therefore, as can be seen from these tables, the conversion coefficient γ _{a associated with} the direction of rotation, which is defined as the product of γ _x and (dx / da), continues to increase.

In particular, in a zoom lens in which the conversion coefficient γ _x , which is assigned to the amount x of a movement, in the direction of the optical axis of the focusing lens unit in a closest state in focus is larger than that in an infinite, state in focus, ie it fulfills:

1.0 <γ _xR / γ _xO

if the focus cam that satisfies the following inequality, d. H. the focus noc ken has a shape that has a larger slope (dx / da) at the closest position speaking position as at the infinitely corresponding position:

1.0 <(dx / da) _R / (dx / da) _O

where the following inequality is satisfied:

1.0 <γ _xR / γ _xO <γ _aR / γ _aO

The rate of change from the infinite focus value (γ _aO ) to the closest focus value (γ _aR ) of the conversion coefficient γ _{a associated with} the angle a of rotation of the rotatable lens barrel undesirably becomes larger than the rate of change from the infinite focus value (γ _xO ) to the closest focus value (γ _xR ) of the conversion coefficient γ _x , which is associated with the amount x of a movement in the direction of the optical axis .

From Tables 3, 4 and 5 above, the rate of change of γ _a x5.43 at the wide-angle end position (F = 36.0), x6.26 at the middle position (F = 50.0) and x4.36 at the telephoto end position (F = 103.0).

As described above, when the conversion coefficient γ changes in accordance with the lens arrangement (e.g., focusing), as disclosed in Japanese Patent Application Laid-Open No. 3-228006, a plurality of data pairs of the conversion coefficient γ and the correction coefficient ε are stored in the storage device in units of a plurality of divided focus areas. Therefore, when the rate of change of γ _{a is} large (γ _aR / γ _aO »1.0), the number of divisions becomes larger and the storage capacity becomes inevitably large, which leads to an increase in cost. For example, if a change in γ _{a is divided} into a single focus area under the state determined by the following inequality:

γ _max / γ _min <1.2

the number N of divisions expressed by the inequality (a) below:

N <log (γ _MAX / γ _MIN ) / log (1.2) (a)

Therefore, the numbers N _W , N _M and N _{T of} the divisions at the wide-angle end position, the middle position and the telephoto end position have large values as follows:

N _W <9.3 N _M <10.1 N _T <8.1

The formula K = γ (1 + ε · ΔBf), which is disclosed in Japanese Patent Application Laid-Open No. 62-170924, is converted to the conversion coefficient K _a , which is assigned to the angle a of a rotation of the rotatable lens drum:

K _a = γ _a (1 + ε · ΔBf)

Then the following formula using a correction coefficient µ (ε = -1 / µ) defines:

K _a = γ _a (1 - ΔBf)

Tables 6, 7 and 8 below summarize the calculation results of the values of the conversion coefficient K _a and the correction coefficient µ in accordance with the embodiment of Japanese Patent Application Laid-Open No. 5-142475 at the wide-angle end position (F = 36.0), the middle position (F = 50.0) and the telephoto end position (F = 103.0) using the above formula together.

In these tables, (R) is the object distance (m), (ANG) is the amount of rotation for focusing from the infinitely corresponding position on the focus cam, (r) is the conversion coefficient γ _a in the direction of rotation, (rs ) is the conversion coefficient K _a , (bf) is the defocus amount (mm), and (l) is the correction coefficient µ. Each table has a matrix structure and eight rows in the vertical direction indicated by (POS), which represent the object positions (R = 10.0, 5.0, 3.0, 2.0, 1.5, 1.0 and 0.85 m), and four pairs (R, ANGLE) in the horizontal direction represent the lens arrangements of the focusing lens unit.

More specifically, the position of the focusing lens in the first pair in the upper two tables in each of tables 6, 7 and 8, that is, in the third and fourth columns, is (R, ANGLE) = (0.0, 0.0), and shows indicates that this position corresponds to the infinitely corresponding position. Therefore, the third column (r) in the first table represents the value of the conversion coefficient γ _a in the direction of rotation when the focusing lens unit is focused on an infinite object, and the fourth column (rs) represents the value of the conversion coefficient K _a represents when the focusing lens unit is moved from a state in focus on an infinite object to a state in focus below an object distance in the second column. Furthermore, the third column (bf) in the second table represents the defocus amount ΔBf from a predetermined imaging position when the position of the focusing lens unit corresponds to the infinitely corresponding position, and the object is arranged at an object distance in the second column, and the fourth column (l) represents the value of the correction coefficient μ when the focussing lens unit is moved from a state in focus on an infinite object to a state in focus under an object distance in the second column.

Similarly, the position of the focusing lens in the fourth pair is in the lower two tables in each of tables 6, 7 and 8, ie in the ninth and tenth columns. (R, ANGLE) = (0.85,10.0), and it indicates that this position corresponds to the closest position in focus (R = 0.85 m). Therefore, the ninth column (r) in the third table represents the value of the conversion coefficient γ _a in the direction of rotation when the focusing lens unit is focused on an object at a closest distance (R = 0.85 m), and the tenth column (rs) represents the value of the conversion coefficient K _a when the focusing lens unit from a state in focus on an object at the closest distance (R = 0.85 m) to a state in focus at an object distance in the second Column is moved. Furthermore, the ninth column (bf) in the fourth table represents the defocus amount ΔBf from a predetermined imaging position when the position of the focusing lens unit corresponds to the position corresponding to the closest position, and the object is arranged at an object distance in the second column, and the tenth column (l) represents the value of the correction coefficient µ when the focusing lens unit from a state in focus at the closest object distance (R = 0.85 m) to a state in focus on the object distance in the second column is moved.

From the above formulas, since the conversion coefficient in the direction of a rotation is calculated by K _a = ΔBf / Δa (where Δa: the amount of a rotation for focusing) and the correction coefficient µ by µ = ΔBf / (1 - K _a / γ _a ) is calculated, the value of the conversion coefficient K (eighth row, fourth column in the first table: 0.175) when the focusing lens unit from a state in focus on the infinite object to a state in focus under the object distance (R = 0.85 m), calculated in Table 6 by K _a = 1.75 / 10.0 = 0.175 using ΔBf = 1.75 and Δa = 10.0. On the other hand, the value of the correction coefficient µ (eighth row, fourth column in the second table: -1.00) is calculated as µ = -1.00 using ΔBf = 1.75, K _a = 0.175, and γ _a = 0.064.

Table 6

Conversion coefficient K _a : (rs), γ _a : (r) associated with the direction of rotation, and correction coefficient µ: (l) at the wide-angle position (36.0 mm) of the embodiment of Japanese Patent Application Laid-Open No. 5-142475

f = 36.0 mm

Table 7

Conversion coefficients K _a : (rs), γ _a : (r) assigned to the direction of rotation, and correction coefficient µ: (l) at the central position (50.0 mm) of the embodiment of Japanese Patent Application Laid-Open No. 5-142475

f = 50.0 mm

Table 8

Conversion coefficient K _a : (rs), γ _a : (r) assigned to the direction of rotation, and correction coefficient µ: (l) at the telephoto end position (103.0 mm) of the embodiment of Japanese Patent Application Laid-Open No. 5-142475

f = 103.0 mm

As can be seen from Tables 6, 7 and 8 above, when there is a change in the conversion coefficient K _a : (rs) (e.g. the fourth column in the first table) and a change in the correction coefficient µ: (l) (e.g. the fourth column in the second table) for a given lens arrangement (e.g. the infinite arrangement in focus) are taken into account, the conversion coefficient K _a and the correction coefficient µ considerably in Dependence of the object position. In particular, the conversion coefficient K _{a has} a larger value on the closest object side than that on the infinite object side. Since the conversion coefficient K _a in the direction of rotation is defined by K _a = ΔBf / Δa, the amount Δa of rotation for focusing on the infinite object side becomes larger than that on the closest object side relative to the defocus amount ΔBf.

The calculation results of the rate of change of K _a with respect to γ _a at the infinite arrangement in focus and the closest arrangement in focus at the wide-angle end position (F = 36.0), the middle position (F = 50.0) and the telephoto end position ( F = 103.0) in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 are as follows.

Embodiment of Japanese Patent Application Laid-Open No. 5-142475

As described above, in the embodiment of Japanese Patent Application Laid-Open No. 5-142475, since the change in the conversion coefficient K _{a is} large, the contribution of the correction term (ΔBf / µ) in K _a = γ _a (1 - ΔBf / µ) is large and the value of the correction coefficient µ comes close that of the defocus amount ΔBf. In addition, the value of the correction coefficient µ changes greatly depending on the object positions.

Therefore, as in Japanese Patent Application Laid-Open No. 3-228006, under the condition that only a pair of a conversion coefficient value γ _a and a correction coefficient value µ are set for a given lens array range (e.g., an infinite focus array array) if the correction coefficient µ, which changes greatly, is represented by only one value _, including a large error in the value of the conversion coefficient K _a , which is calculated from the conversion coefficient γ _a and the correction coefficient µ. Therefore, when the lens driving amount Δa for focusing is finally calculated from the defocusing amount ΔBf using the conversion coefficient K _a , the lens driving amount includes an error and an auto-focusing operation cannot be performed accurately.

For example, calculating the lens drive amount Δa for focusing on a closest object distance (R = 0.85 m) when the correction coefficient µ (which changes from -3.76 to -5.77 depending on the object distances) on the infinite arrangement in focus at the telephoto end position (F = 103.0) is represented by the value (µ = -4.82) at the mean object distance (R = 2.0 m), the lens drive amount Δa for focusing as Δa = 8.74 by substituting ΔBf = 16.18, γ _a = 0.425 and µ = -4.82 calculated. The actual lens drive amount for focusing from the state of the infinite arrangement in focus at the telephoto end position (F = 103.0) to the closest object distance (R = 0.85 m) is Δa = 10.0 from (R, ANGLE) = (0.85 , 10.0) in the upper right position of the third table in Table 8. Therefore an error of up to -12.6% between the actual value and the calculated value Δa = 8.74 of the lens drive amount for focusing is generated.

Similarly, when the lens driving amounts were in focus from the infinite, in-focus lens array to the closest object distance and in focus from the closest, in-focus lens array to the infinite object distance at the wide-angle end position, the center position, and the Telephoto end position can be calculated from Δa = ΔBf / γ _a (1 - ΔBf / µ) and then errors can be calculated from the actual lens drive amounts, the following large values being obtained.

Embodiment of Japanese Patent Application Laid-Open No. 5-142475

It should be noted that the value of the correction coefficient µ when focusing the infinite, in focus lens arrangement to the closest Ob object distance assumes a value at the object distance (R = 2.0 m), and the value of the Correction coefficients µ focusing from the closest one in focus Chen lens arrangement to the infinite object distance a value at the object distance stand (R = 3.0 m).

Finally, Table 9 summarizes the amount (ANGLE DA) of a rotation for focusing manual focusing using the focus cam (the middle one) Table in Table 1) of the embodiment of Japanese Patent Application Laid-Open manure No. 5-142475, the amount DX (mm) of a movement, in the direction of the optical axis, the focusing lens unit corresponding to the amount of a ro tation for focusing, and a shift amount Bf (mm) of the imaging Point if the amount (DX) of a movement in the direction of the optical axis before is given together.

The upper table in Table 9 summarizes the shift amount (Bf) of the imaging Points corresponding to the photographing distances (R = 5.0, 3.0, 2.0, 1.5, 1.0 and 0.85 m) in the respective zooming states of the focus lengths (F = 36.0, 50.0, 60.0, 70.0, 85.0 and 103.0 mm) together, and the middle table summarizes the values of the amount (ANGLE DA) a rotation for focusing, which is used to achieve an opti paint, in the state in focus with regard to the respective photography stands are required. The table below summarizes the amounts (DX) of a movement the direction of the optical axis of the respective lens units in accordance with the Be carrier (ANGLE DA) of a rotation for focusing in association with the focus lengths and the photographing distances together. In the table below, (F) is the focus length (mm) of the entire system, (R) is the photographing distance (m) and (DX) is the amount (mm) a movement in the direction of the optical axis of each of the first, second, third and fourth lens units in series from the right side (the movement towards the object side is represented by a positive value).  

Table 9

Displacement amount Bf (mm) of an imaging point and amount DX (mm) of a movement for focusing in the embodiment of Japanese Patent Application Laid-Open No. 5-142475

Summary of the invention

It is therefore an object of the present invention to provide a zoom lens which can suppress changes in the conversion coefficient _a and the correction coefficient µ above, especially when the focus cam is used to achieve manual focusing by reducing the memory capacity by reducing the Can suppress the number of data of the conversion coefficient γ _a and the correction coefficient µ to be stored in the storage device, which can eliminate an error in calculating the lens driving amount Δa for focusing from the defocus amount ΔBf using the conversion coefficient K _a and which can accurately correct the car -Focusing can achieve.

According to the first aspect of the present invention, in a zoom lens or zoom lens system in which the movement point of a focusing lens unit is determined by synthesizing a first focus cam and a zoom compensation cam so as to be in focus State by a substantially constant amount of rotation for an identical object distance was independent of a zooming state, specifying a predetermined movement point for zooming by the amount of movement in the direction of the optical axis, the lens units and the angle of rotation of a rotatable lens. or lens drum when the ratio (dBf / dx: sensitivity associated with the direction of the optical axis) of the amount dBf of an inifinitesimal movement of the imaging plane to the amount dx of an infinitesimal movement in the direction of the optical axis of the focusing lens unit , and the ratio nis (dBf / da: the sensitivity associated with the direction of a rotation) of the amount dBf of an infinitesimal movement of the imaging plane to the angle da of an infinitesimal rotation of the focusing lens unit on the focus _cam by γ _xO and γ _{aO respectively} infinite point in focus are shown and each represented by γ _xR and γ _aR at the closest point in focus, the zoom lens fulfilling the condition formula (1) at least at the telephoto end position:

1.0 <γ _xR / γ _xO (1)

At the same time, the ratio of the size a _F satisfies a rotation of the focusing lens unit on the focus cam, the magnitude of a focus corresponding to the amount from the infinite state in focus to the closest state in focus a _{Z of} a rotation corresponding to zooming from the wide-angle end position to the telephoto end position, the state formula (2):

-1.0 <a _F / a _Z <-0.7 (2)

Under these conditions, the zoom lens at least fulfills a state formula (3) at the wide-angle end position and the telephoto end position:

0.3 <γ _aR / γ _aO <0.7 (3)

In the zoom lens system in which the moving position of the focusing lens unit is determined by synthesizing a focus cam and a zoom compensation cam so as to maintain a state in focus with a substantially constant amount of rotation for an identical one To achieve object distance regardless of a zooming state if the values of the conversion coefficient K _a , which are used when the focusing lens unit is arranged on the lens arrangements in accordance with the infinite state in focus and the closest state in focus and expressed by K _a = ΔBf / Δa, each represented by K _aO and K _aR , the zoom lens fulfills the following formulas at least at the wide-angle end position and the telephoto end position:

0.6 <K _aO / γ _aO <1.2

0.8 <K _aR / γ _aR <1.7

in which
ΔBf = the defocus amount between the imaging position of an object at an arbitrary and a predetermined imaging point position,
Δa = the angle of rotation of the focusing lens unit on the focus cam, which is required to achieve a state on the object that is in focus.

According to the first aspect of the present invention, since the above-mentioned state formulas are satisfied, even when the focus cam is used to achieve a so-called manual focus. Changes in the conversion coefficient γ _a and correction coefficient µ, which are necessary for realizing an accurate auto-focusing, are reduced. For this reason, the number of data of the conversion coefficient γ _a and the correction coefficient µ that must be stored in the storage device can be reduced. Furthermore, since the change in the correction coefficient µ is small, an error in the calculation of the lens driving amount Δa for focusing from the defocus amount ΔBf using the conversion coefficient K _{a is} small, and accurate auto-focusing can be realized.

As described above, when the zoom lens system is formed of n lens units and its kth lens unit is used as a focusing lens unit, the conversion coefficient γ _{x associated with} the focusing lens unit in the optical axis direction is assigned (the ratio dBf / dx of the amount dBf of an infinitesimal movement of the imaging plane to the amount dx of an infinitesimal movement in the direction of the optical axis), using the imaging magnifications β of the respective lens units, is expressed as follows:

γ _x = (1 - β _k ²) β _{k + 1} ²β _{k + 2} ². . . β _n ²

Therefore, the rate of change from the infinite focus value (γ _xO ) to the closest focus value (γ _xR ) of the conversion coefficient γ _{x associated with} the direction of the optical axis can be made using the image magnifications β _OK and β _{RK of} the focusing lens unit at the infinite and at the closest point in focus are expressed as follows:

γ _xR / γ _xO = (1 - β _RK ²) / (1 - β _OK ²)

On the other hand, the conversion coefficient γ _{a associated with} the direction of rotation of the focusing lens unit (the ratio dBf / da of the amount dBf of an infinitesimal movement of the imaging plane to the angle da of an infinitesimal rotation) can be expressed by:

γ _a = γ _x · (dx / da)

where dx / da is the slope of the focus cam. For this reason, the rate of change from the infinite focus value (γ _aO ) to the _closest focus value (γ _aR ) of the conversion coefficient γ _{a associated with} the direction of the focusing lens unit can be as follows using the slopes (dx / da) _O and (dx / da) _R at the position corresponding to the infinite and the closest position on the focus cam by:

γ _aR / γ _aO = (γ _xR / γ _xO ) ((dx / da) _R / (dx / da) _O )

Therefore, according to the present invention, in the zoom lens that the State formula (1) satisfies:

1.0 <γ _xR / γ _xO (1)

That is, in the zoom lens system in which the value of the conversion coefficient γ _{x is} the closest to the amount x of movement in the direction of the optical axis of the focusing lens unit. the focus in the assigned state is greater than that in the infinite focus, the ratio of the amount a _{F to} a rotation of the focusing lens unit on the focus cam corresponding to the focusing of the infinite itself state in focus to the closest state in focus and the amount a _{Z of} a rotation corresponding to zooming from the wide angle end position to the telephoto end position so as to satisfy the state formula (2):

-1.0 <a _F / a _Z <-0.7 (2)

Under this condition, as described in detail in the description of the embodiments will be described, the focus cams have a shape where the slope (dx / da) at the position corresponding to the closest position becomes smaller than that at the infinitely corresponding position, d. H. a form that the following formula satisfied:

0 <(dx / da) _R / (dx / da) _O <1.0

The rate of change (γ _aR / γ _aO ) from the infinite focus value (γ _aO ) to the closest focus value (γ _aR ) of the conversion coefficient γ _{a associated with} the direction of rotation is called a product of the rate of change (γ _xR / γ _xO ) of the conversion _ratio γ _x , which is assigned to the direction of the optical axis, and the pitch ratio (dx / da) _R / (dx / da) _{O of} the focus cam becomes as follows expressed:

γ _aR / γ _aO = (γ _xR / γ _xO ) ((dx / da) _R / (dx / da) _O )

For this reason, the two changes cancel each other out, and the _{final rate of} change (γ _aR / γ _aO ) of the conversion coefficient γ _a , which is assigned to the direction of a rotation, can be set to a small value which corresponds to the state formula (3 ) Fulfills:

0.3 <γ _aR / γ _aO <0.7 (3)

As described above, since the change in the conversion coefficient γ _a can be reduced compared to that in the conventional system, the number of the data of the conversion coefficient γ _a and the correction coefficient µ to be stored in the storage device can be reduced.

For example, dividing the focus area similar to the formula (a) (N <log (γ _MAX / γ _MIN ) / log (1.2)) above, the number of divisions becomes:

2.0 <log (γ _MAX / γ _MIN ) / log (1.2) <6.6

and the number of divisions can be smaller than in the conventional system. Therefore, costs in the form of storage capacity can be reduced. Further, as will be described later in the following description of the embodiments, since the changes in the conversion coefficient K _a and correction coefficient µ are smaller than those in the conventional system, an error caused by calculating the lens driving amount Δa to focus from the defocus is obtained using the conversion coefficient K _a , small, and an accurate auto-focusing operation can be realized.

The state formulas of the present invention are explained below.

The state formula (1) is assigned to the focusing lens unit in the zoom lens according to the present invention. When the range of the state _formula (1) exceeds (γ _xR / γ _xO <1.0), the conversion coefficient γ _{x associated with} the direction of the optical axis becomes smaller in the closest state in focus than that of the infinite one state in focus. For this reason, when the focus cam (0 <(dx / da) _R / (dx / da) _O <1.0) is used according to the present invention, the rate of change of the conversion coefficient γ _{a is} that of the direction of rotation is assigned, the rate being expressed as a product of the rate of change (γ _xR / γ _xO ) of the conversion coefficient γ _x , the direction of the optical axis and the pitch _ratio ((dx / da) _R / (dx / da) _O ) of the focus noc kens is much smaller than 1.0 (γ _aR / γ _aO «1.0) and changes in γ _{a become} large. As a result, the number of data of the conversion coefficient γ _a and the correction coefficient µ which must be stored in the storage device increases. In addition, since the changes in the conversion coefficient K _a and the correction coefficient µ become large, an error obtained by calculating the lens driving amount Δa from the defocusing amount ΔBf becomes large, and an accurate auto-focusing operation cannot be performed.

The state formula (2) defines a suitable ratio of the amount a _{F of} a rotation of the focusing lens units on the focus cam in accordance with a focus from the infinite state in focus to the closest state in focus to the amount a _Z a rotation corresponding to zooming from the wide-angle end position to the telephoto end position. If the ratio is smaller than the lower limit of the formula (2), the slope (dx / da) of the focus cam lowers considerably at the closest position compared to the slope at the infinitely corresponding position, and they have a ratio:

0 <(dx / da) _R / (dx / da) _O «1.0

For this reason, the rate of change (γ _aR / γ _aO ) of the conversion coefficient γ _{a associated with} the direction of rotation, the rate being a product of the rate of change (γ _xR / γ _xO ) of the conversion coefficient γ _x that of the direction the optical axis and the pitch ratio ((dx / da) _R / (dx / da) _O ) of the focus cam, is expressed, is much smaller than 1.0 (γ _aR / γ _aO «1.0) and changes in γ _{a get} big. As a result, the number of data of the conversion coefficient γ _a and the correction coefficient µ which must be stored in the storage device increases. In addition, since changes in µ are large, an error obtained by calculating the lens driving amount Δa from the defocus amount ΔBf becomes large, and an accurate auto-focusing operation cannot be performed.

In order to obtain an accurate auto-focusing operation by further reducing changes in γ _a , reducing the number of data of the conversion coefficient γ _a and the correction coefficient µ to be stored in the storage device, and reducing changes in µ, the the lower limit of the state formula (2) is preferably set up as follows:

-0.95 <a _F / a _Z <-0.7

In contrast, when the ratio exceeds the upper limit of the state _formula (2) because the rate of change (γ _aR / γ _aO ) of the conversion coefficient γ _a becomes closer to 1.0, changes in γ _{a become} small and the number of data of the conversion coefficient γ _a and the correction coefficient µ, which must be stored in the storage device, can be reduced. However, since the amount a _{F of} the rotation for focusing becomes small relative to the amount a _Z of rotation corresponding to zooming from the wide-angle end position to the telephoto end position, the amount of rotation for so-called manual focusing becomes small, and it becomes difficult to manually to maintain an accurate focus. Furthermore, in order to ensure good operability of manual focusing, the upper limit must preferably be set to -0.75.

The state formula (3) is a state which is assigned to the number of data of the conversion coefficient γ _a and the correction coefficient μ which has to be stored in the storage device, ie the number of divisions of the focus area. If γ _aR / γ _{aO is} smaller than the lower limit of the state _formula (3), the rate of change (γ _aR / γ _aO ) of the conversion coefficient γ _a becomes much smaller than 1.0 and changes in γ _a become large. As a result, the number of data of the conversion coefficient γ _a and the correction coefficient µ to be stored in the storage device increases, so that a storage device with a large storage capacity is required, which leads to an increase in cost.

In contrast, when γ _aR / γ _{aO exceeds} the upper limit of the state _formula (3), since the rate of change (γ _aR / γ _aO ) of the conversion coefficient γ _a comes closer to 1.0, changes in γ _{a become} small and the number of data the conversion coefficient γ _a and the correction coefficient µ, which must be stored in the storage device, can be reduced. However, as will be described later in the description of the embodiments, since the conversion coefficient γ _a must have _a considerably large value, the sensitivity (dBf / da) associated with the movement in the direction of rotation becomes accurate and one The change in the imaging point caused by a small error factor in the direction of rotation becomes large, thereby disrupting accurate auto-focus.

Furthermore, in order to obtain accurate auto-focus while the sens (dBf / da) associated with the movement in the direction of rotation is set, the upper limit of the state formula (3) preferably as follows fixed:

0.3 <γ _aR / γ _aO <0.6

In order to obtain a zoom lens that can perform auto-focusing more accurately when the conversion coefficients K _a (= ΔBf / Δa) are used when the focusing lens unit on the lens arrays corresponds to the infinite state in focus and the closest, in focus is arranged, each represented by K _aO and K _aR , the zoom lens preferably fulfills at least one of the state formulas (4) and (5) below at least at the wide-angle end position and the telephoto end position:

0.6 <K _aR / γ _aO <1.2 (4)

0.8 <K _aR / γ _aO <1.7 (5)

The state formula (4) determines the rate of change of the conversion coefficient K _a in the direction of rotation while changing an object position when the focusing lens unit corresponds to an arrangement in the infinite state in focus. If the rate is less than the lower limit of the state _formula (4), the change in the conversion _coefficient K _aO under a change in the object position becomes too small compared to the conversion coefficient γ _aO , like the sensitivity that the movement in the direction of rotation is assigned to the focusing lens unit at the infinite point in focus. _Therefore , for example, if the conversion _coefficient K _aO , which is a change in the object position, is determined by a pair of a conversion coefficient _value γ _aO and a correction coefficient _value µ _aO based on the ratio K _aO = γ _aO (1 - ΔBf / µ _aO ) is expressed, a large error in the value of the conversion _coefficient K _aO, which is _calculated from the conversion coefficient γ _aO and the correction _coefficient µ _aO , is generated, as a result of which an accurate auto-focusing is disturbed.

In contrast, when the rate exceeds the upper limit of the state _formula (4), the change in the conversion _coefficient K _aO in the direction of rotation under a change in the object position becomes large compared to the conversion coefficient γ _aO in the direction a rotation of the focusing lens unit at the infinite point in focus. For this reason, when the conversion _coefficient K _aO that changes with a change in the optical position is expressed by a pair of a conversion coefficient _value γ _aO and a correction coefficient value µ _aO , a large error in the value of the conversion coefficient K _{aO becomes} produced, which is calculated from the conversion coefficient γ _aO and the correction coefficient µ _aO .

To achieve auto-focusing more accurately, the top and bottom are Limit of the state formula (4) is preferably set as follows:

0.7 <K _aO / γ _aO <1.1

Similarly, when the conversion _coefficient K _{aO changes} from (K _aO / γ _aO <1) to (K _aO / γ _aO <1) with a change in the object position, when the focusing lens unit of an arrangement in the infinite, im Focus corresponds to the _current state, the sign of the correction _coefficient µ _aO before and after (K _aO / γ _aO = 1). As a result, when the conversion _coefficient K _{aO is expressed} by a pair of a conversion coefficient value γ _aO and a correction coefficient _value µ _aO , a large error in the value of the conversion _coefficient K _aO produced from the conversion coefficient γ _aO and the correction _coefficient µ _{aO is produced} is calculated. Therefore, the conversion _coefficient K _aO preferably does not change too much after it _exceeds (K _aO / γ _aO = 1).

Therefore, if the conversion _coefficient K _{aO changes} from (K _aO / γ _aO <1) to (K _aO / γ _aO <1), the zoom lens preferably _{fulfills the following formula} :

0.7 <K _aO / γ _aO <1.1

The state formula (5) specifies the rate of change of the conversion coefficient K _a in the direction of rotation under a change in the object position when the focusing lens unit corresponds to an arrangement in the closest position in focus. If the rate exceeds the upper limit of the state _formula (5), the change in the conversion _coefficient K _aR in the direction of rotation under a change in the object position becomes too large compared to the conversion coefficient γ _aR as the sensitivity to that of movement in the direction a rotation of the focusing lens unit at the closest point in focus is associated. Therefore, for example, when the conversion _coefficient K _aR changes due to a change in the object position, by a pair of a conversion coefficient value γ _aR and a correction coefficient _value µ _aR based on the ratio ses K _aR = γ _aR (1 - ΔBf / µ _aR ) is expressed, a large error in the value of the conversion coefficient K _{aR is} produced, which is calculated from the conversion coefficient γ _aR and the correction _coefficient µ _aR , whereby an accurate auto-focusing is disturbed.

In contrast, when the rate is less than the lower limit in the state formula (5), the change in the conversion _coefficient K _aR in the direction of rotation under a change in the object position becomes small compared to the conversion coefficient γ _aR in the Direction of rotation of the focusing lens unit at the closest point in focus. For this reason, if the conversion _coefficient K _aR that changes under a change in the object position is expressed by a pair of a conversion coefficient _value γ _aR and a correction coefficient value µ _aR , a large error in the value of the conversion coefficient K _{aR is} produced, which is calculated from the conversion coefficient γ _aR and the correction coefficient µ _aR .

To achieve auto-focusing more accurately, the upper and lower limits The state formula (5) is preferably determined as follows:

0.9 <K _aR / γ _aR <1.5

Similarly, when the conversion _coefficient K _{aR changes} from (K _aR / γ _aR <1) to (K _aR / γ _aR <1) with a change in the object position, when the focusing lens unit is closest to an arrangement in focus corresponds to the present state, the sign of the correction _coefficient µ _aR before and after (K _aR / γ _aR = 1). As a result, when the conversion _coefficient K _{aR is expressed} by a pair of a conversion coefficient value γ _aR and a correction coefficient _value µ _aR , a large error is produced in the value of the conversion _coefficient K _aR which is made up of the conversion coefficient γ _aR and the correction _coefficient µ _aR is calculated. Therefore, the conversion _coefficient K _aR preferably does not change too much after it _exceeds (K _aR / γ _aR = 1).

Therefore, especially when the conversion _coefficient K _{aR changes} from (K _aR / γ _aR <1) to (K _aR / γ _aR <1), the zoom lens preferably _{fulfills the following formula} :

0.9 <K _aR / γ _aR <1.5

According to the second aspect of the present invention, in a zoom lens system in which the moving position of a focusing lens unit is defined by synthesizing a focus cam and a zoom compensation cam, so as to be in a state in focus by a substantially constant amount of rotation for an identical object distance regardless of a zooming state, specifying a predetermined moving point for zooming by the amount of movement, in the direction of the optical axis of the lens units, and the angle of rotation of a rotatable lens barrel when the ratio (dBf / dx) of the amount dBf of an infinitesimal movement of the imaging plane to the amount dx of an infinitesimal movement in the direction of the optical axis of the focusing lens unit at the infinite and closest points in focus represented by γ _xO and γ _xR , respectively be the Betr saw a movement in the direction of the optical axis of the focusing lens unit, which is represented by Δx _WR and Δx _TR for focusing from the infinity position to the closest distance position at the wide-angle end position and the telephoto end position, and the amount of rotation the focusing lens unit on the focus cam corresponds to zooming from the wide-angle end position to the telephoto end position and the amount of rotation corresponding to focusing from the infinite, in-focus state to the closest, in-focus state by a _Z and a, respectively _F to achieve the zoom objective, the state formulas (6), (7) and (8) below at least at the telephoto end position:

1.00 <γ _xR / γ _xO <1.80 (6)

3.20 <Δx _TR / Δ _WR <4.50 (7)

-0.90 <a _F / a _Z <-0.70 (8)

Alternatively, the zoom lens fulfills the state formulas (9), (10) and (11) below:

1.00 <γ _xR / γ _xO <1.80 (9)

2.00 <Δx _TR / Δ _WR <3.20 (10)

-1.00 <a _F / a _Z <-0.80 (11)

On the other hand, if the ratios (dBf / da) of the amount dBf of an infinitesimal movement of the imaging plane with respect to the angle da of an infinitesimal rotation of the focusing lens unit on the focus cam at the infinite and closest points in focus are each by γ _aO and γ _aR who the zoom lens the following formula at least at the wide-angle end position and the telephoto end position

0.25 <γ _aR / γ _aO <0.70

Furthermore, if the conversion coefficients K _a , which are used when the focusing lens unit are arranged on the lens arrangements corresponding to the infinite and the closest state in focus and are expressed by K _a = ΔBf / Δa, are each _satisfied by K _aO and K _aR who the zoom lens the following formulas at least at the wide-angle end position and the telephoto end position:

0.60 <K _aO / γ _aO <1.20

0.80 <K _aR / γ _aR <1.70

in which
ΔBf = the defocus amount between the imaging position of an object at an arbitrary position and a predetermined imaging point position,
Δa = the angle of rotation from the focusing lens unit on the focus cam, which corresponds to reaching a state in focus on the object.

According to the first aspect of the present invention mentioned above, according to the second aspect of the present invention, since the above-mentioned state formulas are satisfied, even when the focus cam is used to achieve so-called manual focusing, changes in the conversion coefficient γ can be made _a and in the correction coefficient µ, which are necessary for realizing an accurate auto-focusing, are reduced.

For this reason, the number of data of the conversion coefficient γ _a and the correction coefficient µ that must be stored in the storage device can be reduced. Furthermore, since the change in the correction coefficient µ is small, an error in calculating the lens driving amount Δa for focusing from the defocusing amount ΔBf using the conversion coefficient K _{a is} small, and accurate auto-focusing can be realized.

As described above, when the zoom lens system is constructed by n lens units and its kth lens unit is used as a focusing lens unit, the conversion coefficient γ _{x associated with} the direction of the optical axis of the focusing lens unit is assigned (the ratio dBf / dx of the amount dBf of an infinitesimal movement of the imaging plane to the amount dx of an infinitesimal movement in the direction of the optical axis) is expressed as follows using the imaging magnifications β of the respective lens units:

γ _x = (1 - β _k ²) β _{k + 1} ²β _{k + 2} ². . . β _n ²

Therefore, the rate of change from the infinite focus value (γ _xO ) to the closest focus value (γ _xR ) of the conversion coefficient γ _{x associated with} the direction of the optical axis can be made using the image magnifications β _Ok and β _{Rk of} the focusing lens unit at the infinite and the closest point in focus are expressed as follows:

γ _xR / γ _xO = (1 - β _Rk ²) / (1 - β _Ok ²)

On the other hand, the conversion coefficient γ _{a associated with} the direction of rotation of the focusing lens unit (the ratio dBf / da of the amount dBf of an infinitesimal movement of the imaging plane to the angle da of an infinitesimal rotation) can be expressed by:

γ _a = γ _x · (dx / da)

where dx / da is the slope of the focus cam. For this reason, the rate of change from the infinite focus value (γ _aO ) to the closest focus value (γ _{α R} ) of the conversion coefficient γ _{a associated with} the direction of rotation of the focusing lens unit can using the slopes (dx / da) _O and (dx / da) _R at the infinite and the closest position on the focus cam are expressed as follows:

γ _aR / γ _aO = (γ _xR / γ _xO ) ((dx / da) _R / (dx / da) _O )

Therefore, according to the present invention, in the zoom lens system in which the value of the conversion coefficient γ _x , which is assigned to the amount x of movement, becomes closest to the focus in the direction of the optical axis of the focusing lens unit State greater than that of the infinite state in focus (1.0 <γ _xR / γ _xO ) the ratio of the amount a _{F of} a rotation of the focusing lens unit on the focus cam corresponding to the focusing of the infinite state in focus to the closest state in focus and the amount a _z of rotation corresponding to zooming from the wide-angle end position to the telephoto end position is set to be negative (a _F / a _Z <0) so that the focus The cam can have a shape in which the slope (dx / da) at the position corresponding to the closest position is smaller than that at the infinite position position (0 <(dx / da) _R / (dx / da) _O <1.0), thereby reducing the change in the conversion coefficient γ _{a associated with} the direction of rotation.

More specifically, since the rate of change (γ _aR / γ _aO ) from the infinite focus value (γ _aO ) to the closest focus value (γ _aR ) of the conversion coefficient γ _a , which is the direction of a Rotation is assigned as a product of the rate of change (γ _xR / γ _xO ) of the conversion _ratio γ _{x associated} with the direction of the optical axis and the pitch ratio (dx / da) _R / (dx / da) _{O of} the focus In terms of cam, as described above, the final rate of change (γ _aR / γ _aO ) of the conversion coefficient γ _{a associated with} the direction of rotation will be compressed by adapting an arrangement in which two changes cancel each other out .

According to the present invention, in a zoom lens in which the conversion coefficients γ _x corresponding to the amount x of movement in the direction of the optical axis of the focusing lens unit at the infinite and the closest point in focus at the telephoto end position the following formula (6) satisfies:

1.00 <γ _xR / γ _xO <1.80 (6)

When the relationship between the amounts Δx _WR and Δx _{TR of} the movement in the direction of the optical axis of the focusing lens unit required for focusing from the infinity position to the position at the closest distance at the wide-angle end position and the telephoto end position is as follows State formula (7) fulfilled:

3.20 <Δx _TR / Δ _WR <4.50 (7)

The ratio of the amount a _{F of} a rotation of the focusing lens unit on the focus cam corresponding to a focusing from the infinite state in focus to the closest state in focus to the amount a _{Z of} a rotation corresponding to a zooming from that The wide-angle end position to the telephoto end position is set so that it fulfills the following state formula (8):

-0.90 <a _F / a _Z <-0.70 (8)

Under these conditions, the final rate of change (γ _aR / γ _aO ) of the conversion coefficient γ _{a associated} with the direction of rotation can be set to be a small value that corresponds to the state formula (12) described later , Fulfills.

Alternatively, according to the present invention, in a zoom lens in which the conversion coefficients γ _{x are} assigned to the amount x of a movement, in the direction of the optical axis of the focusing lens unit at the infinite and the closest point in focus at the telephoto end position the state formula (9) fulfills:

1.00 <γ _xR / γ _xO <1.80 (9)

When the ratio between the amounts Δx _WR and Δx _{TR of} the movement in the direction of the optical axis of the focusing lens unit required for focusing from the infinite position to the closest closest position at the wide-angle end position and the telephoto end position, the state formula (10) fulfilled:

2.00 <Δx _TR / Δ _WR <3.20 (10)

The ratio of the amount a _{F of} a rotation of the focusing lens unit on the focus cam corresponding to a focus corresponding to the infinite state in focus to the closest state in focus to the amount a _{Z to} a rotation corresponding to a zooming from The wide-angle end position to the telephoto end position is set in order to fulfill the state formula (11):

-1. 99999 00070 552 001000280000000200012000285919988800040 0002019530770 00004 9988000 <a _F / a _Z <-0.80 (11)

Under these conditions, the final rate of change (γ _aR / γ _aO ) of the conversion coefficient γ _{a associated with} the direction of rotation can be set to be a small value that satisfies the state formula (12) below:

0.25 <γ _aR / γ _aO <0.70 (12)

As described above, since the change in the conversion coefficient γ _a can be reduced compared to that of the conventional system, the number of the data of the conversion coefficient γ _a and the correction coefficient µ to be stored in the storage device can be reduced.

For example, by dividing the focus area similar to the formula (a) (N <log (γ _MAX / γ _MIN ) / log (1.2)), the following relationship is satisfied above:

2.0 <log (γ _MAX / γ _MIN ) / log (1.2) <7.6

and the number of divisions can be smaller than in the conventional system. Therefore, the storage capacity cost can be reduced. Further, as will be described later in the following description of the embodiments, since the changes in the conversion coefficient K _a and in the correction coefficient µ are smaller than those in the conventional system, an error that is calculated by calculating the lens drive amount Δa to focus from the defocus amount ΔBf is kept small using the conversion coefficient K _a , and an accurate auto-focusing operation can be realized.

The state formulas of the present invention are explained below.

The state formula (6) is assigned to the focusing lens unit in the zoom lens according to the present invention. If γ _xR / γ _{xO is} smaller than the lower limit in the state _formula (6) (γ _xR / γ _xO <1.0), the conversion coefficient γ _x , which is the direction of the optical axis in the closest state in focus, becomes is ordered, smaller than the one in the infinite focus. For this reason, when the focus cam (0 <(dx / da) _R / (dx / da) _O <1.0) according to the present invention is used, the rate of change of the conversion coefficient γ _a , which is the direction of rotation is assigned, the rate being expressed as a product of the rate of change (γ _xR / γ _xO ) of the conversion coefficient γ _x , which is the direction of the optical axis and the pitch _ratio ((dx / da) _R / (dx / da) _O ) of Focus cam is assigned, much smaller than 1.0 (γ _aR / γ _aO «1.0) and changes in γ _a become large. As a result, the number of data of the conversion coefficient γ _a and the correction coefficient µ increases, which must be stored in the storage device. In addition, since the changes in the conversion coefficient K _a and the correction coefficient µ become large, the error obtained by calculating the lens driving amount Δa from the defocus amount ΔBf is large, and an accurate auto-focusing operation cannot be performed.

In contrast, when γ _aR / γ _{aO exceeds} the upper limit of the state _formula (6), since the rate of change (γ _aR / γ _aO ) of the conversion coefficient γ _{a gets} closer to 1.0, changes γ _{a become} small. However, in the zoom lens of the present invention, which satisfies the state formula (7), the optimum ratio of the amount a _F i ner rotation of the focusing lens unit on the focus cam corresponding to a focus falls from the infinite state in focus to the closest state in focus to the amount a _{z of} a rotation corresponding to zooming from the wide-angle end position to the telephoto end position outside a range defined by the state formula (8).

The state formula (7) is associated with the relationship between the amounts of movement in the direction of the optical axis of the focusing lens unit, which is required for focusing from the infinite position to the closest distance position at the wide-angle end position and the telephoto end position. As will be described later in the description of the embodiments, this ratio is an amount corresponding to the ratio of the slope (dx / da) _R at the closest position to the slope (dx / da) _O at the infinity Position on the focus cam is assigned. As the ratio between the two amounts of motion becomes smaller, changes in the slope on the focus cam become smaller. In contrast, as the ratio between the two amounts of movement increases, changes in the slope on the focus cam will increase. Therefore, when the ratio becomes smaller than the lower limit of the state formula (7), changes in the conversion coefficient γ _{a associated} with the direction of rotation become small. However, in the zoom lens of the present invention, which satisfies the state formula (6), the optimum ratio of the amount a _{F of} a rotation of the focusing lens unit on the focus cam corresponding to a focus of the infinite focus is included State to the closest state in focus to the amount a _Z of rotation corresponding to zooming from the wide-angle end position to the telephoto end position outside a range defined by the state formula (8). On the other hand, if the ratio exceeds the upper limit of the state formula (7), since changes in the slope on the focus cam become too large compared to those in the conversion coefficient γ _{x associated} with the direction of the optical axis, changes in the conversion coefficient γ _a , which is assigned to the direction of rotation, is large, and the number of data of the conversion coefficient γ _a and the correction coefficient μ, which must be stored in the storage device, increases. In addition, an accurate auto-focusing process cannot be performed.

In order to obtain an accurate auto-focusing operation by further reducing changes in γ _a , reducing the number of data of the conversion coefficient γ _a and the correction coefficient µ to be stored in the storage device, and reducing the changes in µ the upper limit of the state formula (7) is preferably set as follows:

3.20 <Δx _TR / Δx _WR <4.20

The state formula (8) defines a suitable ratio of the amount a _{F of} a rotation of the focusing lens unit on the focus cam in accordance with a focusing from the infinite state in focus to the closest state in focus to the amount a _{Z is} a rotation corresponding to zooming from the wide-angle end position to the telephoto end position. If the ratio is less than the lower limit of the state formula (8), the slope (dx / da) of the focus cam decreases considerably at the position corresponding to the closest position compared to the slope at the infinitely corresponding position, and they have a relationship:

0 <(dx / da) _R / (dx / da) _O «1.0

For this reason, the rate of change of the conversion coefficient γ _{a associated with} the direction of rotation is expressed as a product of the rate of change (γ _xR / γ _xO ) of the conversion coefficient γ _x that is the direction of the optical axis and the pitch ratio ((dx / da) _R / (dx / da) _O ) of the focus cam, much smaller than 1.0 (γ _aR / γ _aO ) «1.0) and changes in γ _a become large. As a result, the number of data of the conversion coefficient γ _a and the correction coefficient µ which must be stored in the storage device increases. In addition, since changes in µ are large, an error obtained by calculating the lens driving amount Δa from the defocus amount ΔBf is large, and an accurate auto-focusing operation cannot be performed.

In order to obtain an accurate auto-focus operation while still reducing changes in γ _a , the number of data of the conversion coefficient γ _a and the correction coefficient µ to be stored in the storage device is reduced and changes in µ are reduced, whereby the lower limit of the state formula (8) is preferably set as follows:

-0.85 <a _f / a _Z <-0.7

In contrast, if the ratio exceeds the upper limit of the state _formula (8), since the rate of change (γ _aR / γ _aO ) of the conversion coefficient γ _a becomes closer to 1.0, changes in γ _{a become} small, and the number of data of the conversion coefficient γ _a and the correction coefficient µ, which must be stored in the memory device, can be reduced. However, since the amount a _F of rotation for focusing relative to the amount a _Z of rotation corresponding to zooming from the wide-angle end position to the telephoto end position becomes small, the amount of rotation for so-called manual focusing becomes small, and it becomes difficult to manually to achieve an accurate focus.

The state formula (9) is the same as the state formula (6) described above, and is associated with the focusing lens unit in the zoom lens according to the present invention. If γ _xR / γ _{xO is} smaller than the lower limit of the state formula (9) (γ _xR / γ _xO <1.0), the conversion coefficient γ _x , which is assigned to the direction of the optical axis in the closest state in focus is smaller than that in the infinite state in focus. For this reason, when the focus cam (0 <(dx / da) _R / (dx / da) _O <1.0) is used according to the present invention, the rate of change of the conversion coefficient γ _{a associated with} the direction of rotation is used , the rate being a product of the rate of change (γ _xR / γ _xO ) of the conversion coefficient γ _{x associated with} the direction of the optical axis and the slope ratio ((dx / da) _R / (dx / da) _O ) of Focus cam is expressed much smaller than 1.0 (γ _aR / γ _aO «1.0) and changes in γ _a become large. As a result, the number of data of the conversion coefficient γ _a and the correction coefficient μ increases, which must be stored in the storage device. In addition, since the changes in the conversion coefficient K _a and the correction coefficient µ become large, an error obtained by calculating the lens driving amount Δa from the defocus amount ΔBf is large, and an accurate auto-focusing operation cannot be performed.

In contrast, when γ _aR / γ _{aO exceeds} the upper limit of the state _formula (9), since the rate of change (γ _aR / γ _aO ) of the conversion coefficient γ _{a gets} closer to 1.0, changes in γ _{a become} small. However, in the zoom lens of the present invention, which fulfills the state formula (10), the optimal ratio of the amount a _{F of} a rotation of the focusing lens unit on the focus cam corresponding to a focus from the infinite state in focus to the closest state in focus to the amount a _Z of rotation corresponding to zooming from the wide-angle end position to the telephoto end position outside a range defined by the state formula (11).

State formula (10) is the ratio between the amounts of movement in the optical axis direction of the focusing lens unit required for focusing from the infinite position to the closest distance position at the wide-angle end position and the telephoto end position, as above in assigned to the state formula (7). As will be described later in the description of the embodiments, this ratio is an amount related to the ratio of the slope (dx / da) _R at the closest position to the slope (dx / da) _O at the infinitely corresponding one Position on the focus cam is referenced. As the ratio between the two amounts of movement becomes smaller, changes in the slope on the focus cam become smaller. In contrast, as the ratio between the two amounts of a movement increases, changes in the slope on the focus cam become larger. Therefore, when the ratio becomes smaller than the lower limit of the state formula (11), changes in the conversion coefficient γ _{a associated with} the direction of rotation become small. However, in the zoom lens of the present invention that satisfies the state formula (9), the optimum ratio of the amount a _F of rotation of the focusing lens unit on the focus cam corresponding to focusing from the infinite state in focus falls the closest state in focus to the amount a _Z of rotation corresponding to zooming from the wide-angle end position to the telephoto end position outside a range defined by the state formula (11). On the other hand, if the ratio exceeds the upper limit of the state formula (10), because changes in the slope on the focus cam become too large compared to those of the conversion coefficient γ _{x associated with} the direction of the optical axis, changes become in the conversion coefficient γ _a , which is assigned to the direction of rotation, is large, and the number of data of the conversion coefficient γ _a and the correction coefficient µ, which must be stored in the storage device, increases. In addition, accurate auto-focusing operation cannot be performed.

The state formula (11) defines a suitable ratio of the amount a _{F of} a rotation of the focusing lens unit on the focus cam in accordance with a focusing from the infinite state in focus to the closest state in focus to the amount a _Z corresponding to zooming from the wide-angle end position to the telephoto end position as in the state formula (8) before. When the ratio becomes smaller than the lower limit of the state formula (11), the slope (dx / da) of the focus cam decreases considerably at the position corresponding to the closest position compared to the slope at the infinitely corresponding position, and the ratio thereof becomes:

0 <(dx / da) _R / (dx / da) _O «1.0

For this reason, the rate of change (γ _aR / γ _aO ) of the conversion coefficient γ _{a associated with} the direction of rotation, this rate being a product of the rate of change (γ _xR / γ _aO ) of the conversion coefficient γ _x that of the direction is assigned to the optical axis and the pitch ratio (dx / da) _R / (dx / da) _{O of} the focus cam, much smaller than 1.0 (γ _aR / γ _aO «1.0) and changes in γ _a become large. As a result, the number of data of the conversion coefficient γ _a and the correction coefficient µ increases, which must be stored in the storage device. In addition, since changes in µ are large, an error obtained by calculating the lens drive amount Δa from the defocus amount ΔBf is large, and an accurate auto-focusing operation cannot be performed.

In contrast, when the ratio exceeds the upper limit of the state _formula (11), since the rate of change (γ _aR / γ _aO ) of the conversion coefficient γ _{a gets} closer to 1.0, changes in γ _{a become} small and the number of data of the conversion coefficient becomes small γ _a and the correction coefficient µ, which must be stored in the memory device, can be reduced. However, since the amount a _{F of} the rotation for focusing relative to the amount a _Z of rotation corresponding to zooming from the wide-angle end position to the telephoto end position becomes small, the amount of rotation for so-called manual focusing becomes small, and it becomes difficult to manually to get an accurate focus.

The state formula (12) indicates a state which is assigned to the number of data of the conversion coefficient γ _a and the correction coefficient μ which must be stored in the memory device, ie the number of divisions or subdivisions of the focus area. If γ _aR / γ _{aO is} smaller than the lower limit of the state formula (12), the rate of change γ _aR / γ _{aO of} the conversion coefficient γ _{a becomes} much smaller than 1.0 and changes in γ _a become large. As a result, since the number of data of the conversion coefficient γ _a and the correction coefficient µ to be stored in the storage device increases, a storage device with a large storage capacity is required, which leads to an increase in cost.

In contrast, when γ _aR / γ _{aO exceeds} the upper limit of the state _formula (12), since the rate of change (γ _aR / γ _aO ) of the conversion coefficient γ _{a gets} closer to 1.0, changes in γ _{a become} small, and the number of Data of the conversion coefficient γ _a and the correction coefficient µ, which must be stored in the storage device, can be reduced. However, since the conversion coefficient γ _a must have a considerably large value, the sensitivity (dBf / da) associated with the movement in the direction of rotation becomes accurate, and a change in the imaging point caused by a small error factor in the direction of rotation is caused to become large, thereby disturbing accurate auto-focusing.

Furthermore, in order to obtain accurate auto-focus while the Emp sensitivity (dBf / da) is reduced, that of movement in the direction of rotation is assigned, the upper and lower limits of the state formula (12) are preferred set as follows:

0.30 γ _aR / γ _aO <0.60

To obtain a zoom lens that can perform auto-focusing more accurately when the conversion coefficients K _a (= ΔBf / Δa) are used when the focusing lens unit on the lens arrays corresponds to the infinite state in focus and the closest state in focus, represented by K _aO and K _aR , the zoom lens preferably fulfills the following state formulas (13) and (14) at least at the wide-angle end position and the telephoto end position.

0.60 <K _aO / γ _aO <1.20 (13)

0.80 <K _aR / γ _aR <1.70 (14)

The state formula (13) defines the rate of change of the conversion coefficient K _a in the direction of rotation under a change in the object position when the focusing lens unit corresponds to an arrangement in the infinite state in focus. If the rate is less than the lower limit of the state _formula (13), the change in the conversion _coefficient K _aO under a change in the object position becomes too small compared to the conversion coefficient γ _aO as the sensitivity to the movement in the direction of rotation of the focusing lens unit is assigned to the infinite point in focus. Therefore, for example, when the conversion _coefficient K _aO that changes with a change in the object position is given by a pair of a conversion coefficient _value γ _aO and a correction coefficient _value µ _aO based on the relationship K _aO = γ _aO (1 - ΔBf / µ _aO ) is pressed, a large error is generated in the value of the conversion _coefficient K _aO which is calculated from the conversion coefficient γ _aO and the correction _coefficient µ _aO , which consequently disturbs accurate auto-focusing.

In contrast, when the rate exceeds the upper limit of the state _formula (13), the change in the conversion _coefficient K _aO in the direction of rotation under a change in the object position becomes large compared to the conversion coefficient γ _aO in the direction of rotation of the focusing Lens unit at the infinite point in focus. For this reason, when the conversion _coefficient K _aO which changes with a change in the object position is expressed by a pair of a conversion coefficient _value γ _aO and a correction coefficient value µ _aO , a large error is generated in the value of the conversion coefficient K _aO which is calculated from the conversion coefficient γ _aO and the correction coefficient µ _aO .

To achieve auto-focusing more accurately, the top and bottom are Limit of the state formula (13) is preferably set as follows:

0.65 <K _aO / γ _aO <1.10

Similarly, when the conversion _coefficient K _{aO changes} from (K _aO / γ _aO <1) to (K _aO / γ _aO <1) with a change in the object position, when the focusing lens unit of an arrangement in the infinite, in the The state in focus _corresponds to the sign of the correction _coefficient µ _aO before and after (K _aO / γ _aO = 1). Here, when the conversion _coefficient K _{aO is expressed} by a pair of a conversion coefficient value γ _aO and a correction coefficient _value µ _aO , a large error in the value of the conversion _coefficient K _{aO is} generated, which is made up of the conversion coefficient γ _aO and the correction _coefficient µ _aO is calculated. Therefore, the conversion _coefficient K _aO preferably does not change too much after it _exceeds (K _aO / γ _aO = 1).

Therefore, especially when the conversion _coefficient K _{aO changes} from (K _aO / γ _aO <1) to (K _aO / γ _aO <1), the zoom lens preferably changes the following _formula :

0.65 <K _aO / γ _aO <1.10

The state formula (14) defines the rate of change of the conversion coefficient K _a in the direction of rotation under the change in an object position when the focusing lens unit corresponds to an arrangement of the closest position in focus. If the rate exceeds the upper limit of the state _formula (14), the change in the conversion _coefficient K _aR in the direction of rotation under a change in an object position becomes too large compared to the conversion coefficient γ _aR as the sensitivity to that of movement in the Direction of rotation of the focusing lens unit at the closest point in focus is assigned. Therefore, for example, when the conversion _coefficient K _aR that changes with a change in the object position is replaced by a pair of a _conversion coefficient _value γ _aR and a correction coefficient _value µ _aR based on the ratio K _aR = γ _aR (1 - ΔBf / µ _aR ), a large error in the value of the conversion _coefficient K _{aR is} generated which is calculated from the conversion coefficient γ _aR and the correction _coefficient µ _aR , which consequently disturbs accurate auto-focusing.

In contrast, when the rate is smaller than the lower limit of the state formula (14), the change in the conversion _coefficient K _aR in the direction of rotation in the change in an object position becomes small compared to the conversion coefficient γ _aR in the direction one Rotation of the focusing lens unit at the closest point in focus. For this reason, when the conversion _coefficient K _aR that changes under a change in the object position is expressed by a pair of a conversion coefficient _value γ _aR and a correction coefficient value µ _aR , a large error in the value of the conversion coefficient K _{aR is} generated that is calculated from the conversion coefficient γ _aR and the correction coefficient µ _aR .

To achieve auto-focusing more accurately, the upper and lower limits The state formula (14) is preferably determined as follows:

0.90 <K _aR / γ _aR <1.55

Similarly, when the conversion _coefficient K _{aR changes} from (K _aR / γ _aR <1) to (K _aR / γ _aR <1) with a change in the object position, when the focusing lens unit is closest to an arrangement in the Focus corresponds to the _current state, the sign of the correction _coefficient µ _aR before and after (K _aR / γ _aR = 1). As a result, when the conversion _coefficient K _{aR is expressed} by a pair of a conversion coefficient value γ _aR and a correction coefficient _value µ _aR , a large error is generated in the value of the conversion _coefficient K _aR which is made up of the conversion coefficient γ _aR and the correction _coefficient µ _aR is calculated. Therefore, the conversion _coefficient K _{aR preferably} does not change too much after it _exceeds (K _aR / γ _aR = 1).

Therefore, especially when the conversion _coefficient K _{aR changes} from (K _aR / γ _aR <1) to (K _aR / γ _aR <1), the zoom lens preferably _{fulfills the following formula} :

0.90 <K _aR / γ _aR <1.55

The foregoing and other objects, features, and advantages of the present invention are explained below and can be better understood with reference to the Drawings are understood and the description that follows.

Brief description of the drawings

Fig. 1A is a view showing the movement locations for zooming a zoom lens according to a first embodiment of the present invention;

Fig. 1B is a view illustrating the pensationsnockens forms a focus cam, and a zoom-Kom a second lens unit in the zoom lens according to the first embodiment of the present invention;

Fig. 2 is a view for explaining the shape of the focus cam in the zoom lens according to the first embodiment of the present invention;

Fig. 3A is a view showing the moving positions for zooming a zoom lens according to the ninth embodiment of the present invention:

Fig. 3B is a view illustrating the shapes of a focus cam, and a zoom-Kom pensationsnockens a second lens unit in the zoom lens according to the nine th embodiment of the present invention;

Fig. 4 is a view for explaining the shape of the focus cam in the zoom lens according to the ninth embodiment of the present invention;

Fig. 5A is a view of a zoom OBJEK tivs represents the movement for zooming points according to the thirteenth embodiment of the present invention;

Fig. 5B is a view illustrating the pensationsnockens forms a focus cam, and a zoom-Kom a second lens unit in the zoom lens according to the thirteenth embodiment of the present invention; and

Fig. 6 is a view for explaining the shape of the focus cam in the zoom lens according to the thirteenth embodiment of the present invention.

Detailed description of the preferred embodiments

The present invention is detailed below with reference to this embodiment described.

First Embodiment

A zoom lens of the first embodiment is a zoom lens that has a four-unit arrangement, that is, a positive, a negative, a positive, and a positive lens unit, and it focuses by a negative second lens unit, such as in the embodiment of Japanese Patent Application Laid-Open No. 5-142475, which is previously described in detail in the prior art. In this zoom lens, the rotation amount ratio (a _F / a _Z ) of the rotation amount for focusing from the infinite position in focus to the closest position in focus (R = 0.85 m) becomes the amount of rotation set to zoom from the wide-angle end position (F = 36.0) to the telephoto end position (F = 103.0) so that it is -0.75.

Table 10 below summarizes various paraxial data of an optical system and data for defining the shape of a focus cam according to the first embodiment form together.

The upper table in Table 10 summarizes the focus length data and the symmetry point-in tervalldaten the respective lens units of the optical system according to the he most embodiment together. In this table, F1, F2, F3 and F4 are each Focus lengths of the first, second, third and fourth lens units and D1, D2, D3 and D4 are the symmetry point interval between the first and the second line the symmetry point interval between the second and the third Lens unit, the symmetry point interval between the third and fourth lenses unit and the symmetry point interval between the fourth lens unit and one predetermined imaging level in six zooming states (F = 36.0, 50.0, 60.0, 70.0, 85.0 and 103.0 mm). Therefore, this data is the same as the different ones Paraxial data (upper table in Table 1) of the embodiments of Japanese, of filed patent application No. 5-142475.

The middle table in Table 10 summarizes spline sample data when the shape (a slope g _2F in Fig. 1B) of the focus cam in the second lens unit of the first embodiment, which is used for focusing, by a wedge - or spline function is expressed, which is assigned to the angle a of a rotation of the rotatable lens drum and the amount x of a movement in the direction of the optical axis (compare with "Numerical Analysis and FORTRAN", MARUZEN, "Spline Function and Its Applications" , Kyoiku Shuppan and the like).

Furthermore, the lower table in Table 10 summarizes the infinite positions in focus (positions corresponding to infinity) at the respective focus lengths (F = 36.0, 50.0, 60.0, 70.0, 85.0 and 103.0 mm) and the amounts of a rotation (amounts of one Rotation for focusing) focusing on respective photographing distances (R = 5.0 3.0, 2.0 1.5.1.0 and 0.85 m) using the focus cam of the first embodiment together. In the lower table in Table 10, since the amount of rotation for zooming from the wide-angle end position (F = 36.0) to the telephoto end position (F = 103.0) is set to be 10.0 and the amount of rotation for focusing is from the infinite , the focus position to the closest focus position (R = 0.85 m) is set to be -7.5, the rotation amount ratio (a _F / a _Z ) of the rotation amount for focusing to the amount of rotation for zooming in the first embodiment -0.75.

Table 10

First embodiment f = 36.0 to 103.0 (rotation amount ratio: a _F / a _Z = -0.75)

Focus lengths and symmetry point intervals of lens units of the first embodiment

Focus cam shape (wedge interpolation sampling point) according to the first embodiment

Amount of rotation for zooming and amount of rotation for focusing the first embodiment

(Rotation amount ratio: a _F / a _Z = -0.75)

Table 11 below summarizes the numerical data values of the focusing cams the lens unit in the first embodiment, which data by Interpolation based on a wedge function based on the scan data of the focus Cams are calculated as this is summarized in the middle table in Table 10 is composed. In this table, (ANGLE) is an angle of rotation of the rotatable object tivtrommel, (2) is the amount (mm) of movement in the direction of the optical axis the second lens unit and (F) is the focus length (mm) of the entire system in egg an infinite state in focus according to the amount (ANG LE) of a rotation.  

Table 11

Numerical cam value data of a focusing lens unit in the first embodiment

The left table in Table 11 summarizes the numerical data values of the focus cam of the first embodiment and the right table in Table 11 summarizes the numerical data values of the zoom compensation cam of this embodiment. A value obtained by synthesizing the amounts (2) of movement in the direction of the optical axis in the numerical data values of the focus cam and the zoom compensation cam in the range from the amount of rotation (ANGLE = 0.0) to the amount of rotation (ANGLE = 10.0) is obtained agrees with the movement point (a slope g₂ in Fig. 1A) of the second lens unit, which is calculated using the paraxial data in the table above in Table 10.

Therefore, the zoom compensation cam (a slope g _2H in Fig. 1B) by subtracting the focus cam (the slope g _2F in Fig. 1B) from the moving point (the slope g₂ in Fig. 1A) while zooming the second lens unit , which is determined by the Para xialdaten in the upper table in Table 10.

FIGS. 1A and 1B and Fig. 2 will be described briefly below.

Fig. 1A shows the paraxial arrangement of the movement points while zooming the zoom lens according to the first embodiment, and Fig. 1B shows the shapes of the focus cam and the zoom compensation cam of the second lens unit of this embodiment. As now the Fig. 1A and 1B show G1, G2, G3 and G4 each representing the first, second third and fourth lens units, and g₁, g₂, g₃ and g jeweils each representing the movement locations while zooming the first, second, third and fourth lens units g _2F and g _2H respectively represent the shapes of the focus cam and the zoom compensation cam of the second lens unit. As described above, a shape is obtained by synthesizing the focus cam g _2F and the zoom compensation cam g _{2H of} the second lens unit is obtained with the movement point g₂ of the second lens unit.

Fig. 2 is a view for explaining the shape of the focus cam g _2F the first embodiment. . Filters as the FIG 2 shows (f = 36; R = un) and (f = 36; R = 0.85) per weils the focus positions on the infinite and the closest distance (R = 0.85 m) at the wide-angle end is and coordinate positions ( x; a) on the focus noc ken are (x; a) = (0; 0) and (x; a) = (1,037; -7.5). On the other hand, (f = 103; R = un) and (f = 103; R = 0.85) represent the positions in focus at the infinite and the closest distance (R = 0.85 m) at the telephoto end position and coordinate positions (x; a) on the focus cam are (x; a) = (-4.654; 10) and (x; a) = (-0.574; 2.5).

While zooming from the wide-angle end position to the telephoto end position, the second lens unit on the focus cam g _2F moves from the coordinate position (0; 0) to the coordinate position (-4.654; 10) for an infinite object and from the coordinate position (1.037; - 7.5) to the coordinate position (-0.574; 2.5) for an object at a closest distance. Therefore, the second lens unit moves 10.0 in the direction of rotation (the direction on an axis a) in both cases. On the other hand, focusing from the infinite arrangement to the closest object distance on the focus cam g _2F , the second lens unit moves from the coordinate position (0; 0) to the coordinate position (1,037; -7.5) at the wide-angle end position and from the coordinate position ( -4.654; 10) to the coordinate position (-0.574; 2.5) at the telephoto end position. Therefore, the second lens unit moves 7.5 in the direction of rotation (the direction of the axis a) at these ends. In contrast, in the direction of the optical axis (the direction of an axis x), the second lens unit moves by 1,037 at the wide-angle end position and by 4.08 at the telephoto end position.

Tables 12, 13 and 14 below summarize the amount DX (mm) of a movement for focusing in the direction of the optical axis for the focusing lens unit, the image magnifications β _{x of} the respective lens units, the conversion coefficient γ _x , the direction of the optical Axis is assigned, the slope (dx / da) of the focus cam and the conversion coefficient γ _a of the direction of rotation at the wide-angle end position (F = 36.0), the middle position (F = 50.0) and the telephoto end position (F = 103.0) is, each according to the first embodiment together. In these tables, (R) on the left is the photographing distance (m), (ANG) is the amount of rotation on the focus cam focusing on the respective photographing distances, and 1), 2), 3) and 4) the right, each represent the first, second, third and fourth lens unit. Also in these tables, the first table summarizes the amount DX (mm) of a movement for focusing in the direction of the optical axis, focusing on the respective photographing distances (R = 10.0, 5.0, 3.0, 2.0, 1.5, 1.0 and 0.85 m) (note that a movement towards the object side is positive) together. The second table summarizes image magnifications β _{K of} the respective lens units in a state in focus under the respective photographing distances (R = 10.0, 5.0, 3.0, 2.0, 1.5, 1.0 and 0.85 m). The third table summarizes the conversion coefficient γ _x , which corresponds to the direction of the optical axis of the focusing lens unit in a focus state at the respective photographing distances (R = 10.0, 5.0, 3.0, 2.0, 1.5, 1.0 and 0.85 m) is together. Furthermore, the fourth table summarizes the slope (dx / da) of the focus cam at the positions on the focus cam corresponding to a state in focus under the respective photographing distances (R = 10.0, 5.0, 3.0, 2.0, 1.5, 1.0 and 0.85 m) together and the fifth table summarizes the conversion coefficient γ _a , which was the direction of rotation of the focusing lens unit in a state in focus at the respective photography stand (R = 10.0, 5.0, 3.0, 2.0, 1.5, 1.0 and 0.85 m) is assigned together.

Table 12

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the wide-angle end position (36.0 mm) in the first embodiment

Image magnification β _{K of} the lens units at the wide-angle end position (36.0 mm) in the first embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the wide-angle end position (36.0 mm) in the first embodiment

Slope dx / da of the focus cam at the wide-angle end position (36.0 mm) in the first embodiment

Conversion coefficient γ _a , which is assigned to the direction of rotation at the wide-angle end position (36.0 mm) in the first embodiment

Table 13

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the center position (50.0 mm) in the first embodiment

Image magnification β _{K of} the lens units at the central position (50.0 mm) in the first embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the central position (50.0 mm) in the first embodiment

Slope dx / da of the focus cam at the middle position (50.0 mm) in the first embodiment

Conversion coefficient γ _a , which is assigned to the direction of rotation at the center position (50.0 mm) in the first embodiment

Table 14

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the telephoto end position (103.0 mm) in the first embodiment

Image magnification β _{K of} the lens units at the telephoto end position (103.0 mm) in the first embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the telephoto end position (103.0 mm) in the first embodiment

Slope dx / da of the focus cam at the telephoto end position (103.0 mm) in the first embodiment

Conversion coefficient γ _a , which is assigned to the direction of rotation at the telephoto end position (103.0 mm) in the first embodiment

As can be seen from Tables 12, 13 and 14, the conversion coefficient γ _x , which is assigned to the direction of the optical axis, increases with each focus length, but the slope (dx / da) of the focus cam decreases if the photo distance comes closer to the closest distance. Therefore, as can be seen from these tables, the conversion coefficient γ _a , which is assigned to the direction of a rotation and which is defined as the product of the conversion coefficient γ _x and the slope (dx / da) of the focus cam, decreases when the photographer comes closer to the closest distance by the influence of the slope (dx / da) of the focus cam, in contrast to the embodiment of Japanese Patent Application Laid-Open No. 5-142475. From Tables 12, 13, and 14, the rate of change from the infinite focus position to the closest focus position of the conversion coefficient γ _{a associated} with the direction of rotation is x0.50 at the wide-angle end position ( F = 36.0), x0.47 for the middle position (F = 50.0) and x0.34 for the telephoto end position (F = 103.0). When the number N of divisions of the focus area is calculated with a change in the conversion coefficient γ _a in the first embodiment using the formula (a) and with that in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 is compared, the numbers N _W , N _M and N _{T of} the subdivisions at the wide-angle end position, the middle position and the telephoto end position each have the following values:
Embodiment of Japanese Patent Application Laid-Open No. 5-142475
N _W <9.3, N _M <10.1, N _T <8.1
First embodiment
N _W <3.8, N _M <4.1, N _T <5.9.

Therefore, as from a comparison with the previously calculated values in the Embodiment of Japanese Patent Application Laid-Open No. 5-142475 ver is understandable, the values of the first embodiment are noticeably small.

As described above, in the zoom lens of the first embodiment, since the rate of change from the infinite focus position to the closest focus position of the conversion coefficient γ _{a associated with} the direction of rotation, much smaller than that in the embodiment of Japanese Patent Application Laid-Open No. 5-142475, the number of data of the conversion coefficient γ _a and the correction coefficient µ will be reduced and the storage capacity can be reduced.

Tables 15, 16 and 17 summarize the calculation results of the conversion coefficient K _a and the correction coefficient µ at the wide-angle end position (F = 36.0), the middle position (F = 50.0) and the telephoto end position (F = 103.0) according to the first embodiment. In these tables, (R) is the object distance (m), (ANG) is the amount of rotation for focusing from the infinitely corresponding position on the focus cam, (r) is the conversion coefficient γ _a in the direction of rotation, ( rs) is the conversion coefficient K _a , (bf) is the defocus amount (mm) and (l) is the correction coefficient µ. Each table has a matrix structure, and eight columns in the vertical direction denoted by (POS) represent the object positions (R = 10.0, 5.0, 3.0, 2.0, 1.5, 1.0 and 0.85 mm), and four pairs (R , ANGLE) in the horizontal direction represent the lens arrangements of the focusing lens unit.

More specifically, the position of the focusing lens in the first pair in the top two tables in each of tables 15, 16 and 17, that is, in the third and fourth columns, (R, ANGLE) = (0.0, 0.0), and so on indicates that this position corresponds to the position corresponding to infinity. Therefore, the third column (r) in the first table represents the value of the conversion coefficient γ _a in the direction of rotation when the focusing lens unit is focused on an infinite object, and the fourth column (rs) represents the value of the conversion coefficient K _a represents when the focussing lens unit is moved from a state in focus on an infinite object to a state in focus on the object distance in the second column. Furthermore, the third column (bf) in the second table represents the defocus amount ΔBf from a predetermined imaging position when the position of the focusing lens unit corresponds to the infinitely corresponding position and the object is arranged at an object distance in the second column, and that fourth column (l) represents the value of the correction coefficient μ when the focusing lens unit is moved from a state in focus on an infinite object to a state in focus below the object distance in the second column.

Similarly, the position of the focusing lens in the fourth pair in the lower two tables in each of tables 15, 16 and 17, ie in the ninth and tenth columns, (R, ANGLE) = (0.85, -7.5), and them indicates that this position corresponds to the position corresponding to the closest (R = 0.85 m) position in focus. Therefore, the ninth column (r) in the third table represents the value of the conversion coefficient γ _a in the direction of rotation when the focusing lens unit is focused on a closest object distance (R = 0.85 m), and the 10th column (rs) represents the value of the conversion coefficient K _a when the focusing lens unit is moved from a state in focus at the closest object distance (R = 0.85 m) to a focusing state below the object distance in the second column. Furthermore, the ninth column (bf) in the fourth table represents the defocus amount ΔBf from a predetermined imaging position when the position of the focusing lens unit corresponds to the position corresponding to the closest position and the object is arranged at an object distance in the second column , and the 10th column (l) represents the value of the correction coefficient µ when the focusing lens unit from a state in focus at the closest object distance (R = 0.85 m) to a state in focus below the object distance in the second column is moved.

As described above, since the conversion coefficient in the direction of rotation is calculated by K _a = ΔBf / Δa (where Δa: the amount of rotation for focusing), and the correction coefficient µ is calculated by µ = ΔBf / (1 - K _a / γ _a ) is calculated, the value of the conversion coefficient K _a (eighth row, fourth column in the first table: -0.233) when the focusing lens unit from a state in focus at the infinite object position to one in focus located state at the object distance (R = 0.85 m) is calculated in Table 15 by K _a = 1.75 / -7.5 = -0.233 using ΔBf = 1.75 and Δa = -7.5. On the other hand, the value of the correction coefficient µ (eighth row, fourth column in the second table: 7.46) is calculated as µ = 7.46 using ΔBf = 1.75, K _a = -0.233 and q _a = -0.304.

Table 15

Conversion coefficient K _a : (rs), γ _a : (r) assigned to the direction of rotation, and correction coefficient µ: (l) at the wide-angle end position (36.0 mm) of the first embodiment

f = 36.0 mm

Table 16

Conversion coefficient K _a : (rs), γ _a : (r) assigned to the direction of rotation, and correction coefficient µ: (l) at the central position (50.0 mm) of the first embodiment

f = 50.0 mm

Table 17

Conversion coefficient K _a : (rs), γ _a : (r) assigned the direction of rotation and correction coefficient µ: (l) at the telephoto end position (103.0 mm) of the first embodiment

f = 103.0 mm

As can be seen from Tables 15, 16 and 17 above, when there is a change in the conversion coefficient K _a : (rs) (e.g. the fourth column in the first table) under a given lens arrangement (e.g. B. in the infinite, in focus arrangement) is considered, the rate of change small compared with the change in K _a (Tables 6, 7 and 8) in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 that was previously tested.

More specifically, when the fact that the conversion coefficient K _a in the direction of rotation is defined by K _a = ΔBf / Δa and the defocus amount ΔBf is the same as that of the embodiment in Japanese Patent Application Laid-Open No. 5-142475 is viewed under the same lens arrangement, the amount Δa of rotation for focusing in the first embodiment on the infinite object side is relatively smaller than that on the closest object side, as compared with Japanese Patent Application Laid-Open No. 5-142475. In fact, if the ratio between the amount of rotation to focus focusing on the closest distance (R = 0.85 m) and the amount of rotation to focus focusing on the closest distance becomes (R = 5.0 m) in Tables 1 and 10 is calculated, it is 3,379 / 10.0 = 0.338 in the embodiment of the published Japanese patent application No. 5-142475. while it is -0.9 / -7.5 = 0.120 in the first embodiment. As described above, when the focus cam is used with the arrangement of the present invention, since the amount Δa rotation for focusing becomes relatively smaller on the infinite object side, the conversion coefficient K _a becomes relatively large on the infinite object side, and consequently, the change in the conversion coefficient K _a in the direction of rotation can be reduced compared to the conventional system.

The calculation results of the rate of change of K _a with respect to γ _a at the infinite arrangement in focus and the closest arrangement in focus at the wide-angle end position (F = 36.0), the middle position (F = 50.0) and the telephoto end position ( F = 103.0) in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 and in the first embodiment of the present invention are as follows.

Embodiment of Japanese Patent Application Laid-Open No. 5-142475

First embodiment

As described above, according to the present invention, since the rate of change of K _{a in} γ _{a is} small compared to the conventional system, and the contribution of the correction term (ΔBf / µ) in K _a = γ _a (1 - ΔBf / µ) can be reduced, the value of the correction coefficient µ can be set to be large compared to the defocus amount ΔBf, and at the same time the change in the correction coefficient µ can be reduced.

Therefore, even if only a pair of a conversion coefficient value γ _a and a correction coefficient value µ are set for a given lens arrangement range, an error in the conversion coefficient K _a calculated using γ _a and µ or in the actual lens driving amount Δa for focusing can be avoided.

Next, in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 and the first embodiment of the present invention, when the lens driving amounts focus from the infinite focus lens array to the closest object distance and focus from the closest focus lens array to the infinite object distance at Wide-angle end position (F = 36.0), the middle position (F = 50.0) and the telephoto end position (F = 103.0) are calculated from Δa = ΔBf / γ _a (1 - ΔBf / µ), and errors from the actual lens drive amounts are then calculated , get the following values. It should be noted that the value of the correction coefficient µ while focusing from the infinite lens assembly in focus to the closest object distance takes a value at the object distance (POS-5) and the value of the correction coefficient µ while focusing from the am The closest lens arrangement in focus to the infinite object distance assumes a value at the object distance (POS-4).

Embodiment of Japanese Patent Application Laid-Open No. 5-142475

First embodiment

As described above, even if only a pair of a conversion coefficient value γ _a and a correction coefficient value µ are set for a given lens arrangement range, an error between the conversion coefficient K _a calculated from γ _a and µ and the lens driving amount Δa for focusing is determined is small compared to the conventional system, and focusing can be realized with higher accuracy.

For purposes of reference, if there are errors in the lens drive amounts below Focusing from the infinite lens arrangement in focus to that Object distance (R = 10.0 m) and with the closest focus. in fo kus lens arrangement calculated on the object distance (R = 1.0 m) and  be compared, the following results are obtained. As with this table len can be seen, a focusing accuracy can be relatively independent of the Object distance can be improved.

Embodiment of Japanese Patent Application Laid-Open No. 5-142475

First embodiment

Next, a check is made to see if not just an accurate auto focus sation, but also a so-called manual focus in the zoom lens of the first embodiment can be obtained.

Table 18 summarizes the amount (ANGLE DA) of a rotation for focusing under one manual focusing using the focus cam (the middle table in Table 10) of the first embodiment, the amount X (mm) of a movement, namely in the direction of the optical axis of the focusing lens unit accordingly the amount of rotation for focusing, and the shift amount Bf (mm) of  Imaging point when the amount (DX) of movement in the direction of the optical Axis is given together.

The upper table in Table 18 summarizes the amount of shift (Bf) of the map points according to the photographing distances (R = 5.0, 3.0, 2.0, 1.5, 1.0 and 0.85 m) in the respective zooming states of the focus lengths (F = 36.0, 50.0, 60.0, 70.0, 85.0 and 103.0 m) together and the middle table summarizes the values of the amount (ANGLE DA) the rotation to focus together, which is to achieve an opti paint, in the state in focus with regard to the respective photography stands (R = 5.0, 3.0, 2.0, 1.5, 1.0 and 0.85 m) are required. It should be noted that the amounts of a rotation to focus, the values to eliminate any Displacement of the imaging point at the wide-angle end position and the telephoto end position are selected. The table below summarizes the amount (DX) of a Be movement in the direction of the optical axis of the respective lens units correspond according to the amount (ANGLE DA) of a rotation for focusing in association with the Zoom distances (R = 5.0, 3.0, 2.0, 1.5, 1.0 and 0.85 m) in the respective zoom the states with the focus lengths (F = 36.0, 50.0, 60.0, 70.0, 85.0 and 103.0 mm) together. In the table below, (F) is the focus length (mm) of the entire system, (R) is the photographing distance (m) and (DX) is the amount (mm) of movement in the Direction of the optical axis of each of the first, second, third and fourth lenses in order from the right side. It should be noted that the amount is one Movement in the direction of the optical axis towards the object side by a posi tive value is shown.

Table 18

Displacement amount Bf (mm) of an imaging point and amount (DX) (mm) of a movement for focusing in the first embodiment

As can be seen from Table 18, a so-called manual Fo kissing can be obtained since the shift amounts of the mapping point the respective focus lengths and photographing distances are very small, and they fall into within the depth of focus regardless of the zooming state and the Photography distance.

Second Embodiment

The second embodiment is directed to a zoom lens, which has an arrangement with four units, ie a positive, a negative, a positive and a negative lens unit, and a focus by a negative, second lens unit it reaches. In this zoom lens, the rotation amount ratio (a _F / a _Z ) of the rotation amount for focusing becomes from the infinite position in focus to the closest. the focus position (R = 0.5 m) to the amount of rotation for zooming from the wide-angle end position (F = 29.0) to the telephoto end position (F = 102.0) so that it is -0.95.

Table 19 below summarizes various paraxial data of an optical system and Data for defining the shape of a focus cam according to the second embodiment shape together.

The upper table in Table 19 summarizes the focus lengths and the symmetry point interval data of the respective lens units of the optical system corresponding to the second Embodiment in association with six zooming states (focus lengths F = 29.0, 35.0, 50.0, 70.0, 85.0 and 102.0 mm) together.  

The middle table in Table 19 summarizes the wedge scan data if the shape of a focus cam in the second lens unit of the second embodiment, which for Focusing is used, expressed by a wedge function that corresponds to the Angle a of a rotation of a rotatable lens drum and the amount x of a movement is assigned in the direction of the optical axis.

Furthermore, the lower table in Table 19 summarizes the infinite positions in focus (positions corresponding to infinity) at the respective focus lengths (F = 29.0, 35.0, 50.0, 70.0, 85.0 and 102.0 mm) and the amounts of a rotation (amounts of one Rotation for focusing) focusing on respective photographing distances (R = 5.0, 3.0, 2.0, 1.0, 0.7 and 0.5 m) using the focus cam of the second embodiment together. In the lower table in Table 19, since the amount of a rotation for zooming from the wide-angle end position (R = 29.0) to the telephoto end position (F = 102.0) is set to be 10.0, and the amount of a rotation to Focusing from the infinite position in focus to the closest position in focus (R = 0.5 m) is set to be -9.5, the rotation amount ratio (a _F / a _Z ) of the rotation amount for focusing to the amount of rotation for zooming in the second embodiment -0.95.

Table 19

Second embodiment f = 29.0 to 102.0 (rotation amount ratio: a _F / a _Z = -0.95)

Focus lengths and symmetry point intervals of lens units of the second embodiment

Focus cam shape (wedge interpolation sampling point) according to the second embodiment

Rotation amount for zooming and rotation amount for focusing of the second embodiment

(Rotation amount ratio: a _F / a _Z = -0.95)

Table 20 below summarizes the numerical data values of the cams in the focus lens unit in the second embodiment, this data by interpolation based on a wedge function based on the scan data of the Focus cams are calculated, which are summarized in the middle table in Table 19 are summarized. It should be noted that the meanings of the respective symbols in Ta belle 20 are the same as those according to the first embodiment.

Table 20

Numerical cam data values of a focusing lens unit in the second embodiment

The left table in Table 20 summarizes the numerical data values of the focus cam the second embodiment together and the right table in Table 20 summarizes the numerical data values of the zoom compensation cam of this embodiment together. A value obtained by synthesizing the amounts (2) of a movement in the Direction of the optical axis in the numerical data values of the focus cam and the zoom compensation cam in the range of the amount of rotation (ANGLE = 0.0) on the amount of a rotation (ANGLE = 10.0) is correct the movement point of the second lens unit, which using the Pa raxial data is calculated in the upper table in Table 19.

Tables 21, 22 and 23 below summarize the amount DX (mm) of a movement for focusing in the direction of the optical axis of the focusing lens unit, the magnification β _{x of} the respective lens units, the conversion coefficient γ _{x associated with} the direction of the optical axis is the slope (dx / da) of the focus cam and the conversion coefficient γ _a , which is assigned to the direction of rotation at the wide-angle end position (F = 29.0), the middle position (F = 50.0) and the telephoto end position (F = 102.0) , together according to the second embodiment. The arrangements of the respective tables and the meanings of the symbols are the same as those of the first embodiment.

Table 21

Amount DX (mm) of a movement to focus in the direction of the optical axis at the wide-angle end position (29.0 mm) in the second embodiment

Image magnification β _{K of} the lens units at the wide-angle end position (29.0 mm) in the second embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the wide-angle end position (29.0 mm) in the second embodiment

Slope dx / da of the focus cam at the wide-angle end position (29.0 mm) in the second embodiment

Conversion coefficient γ _a , which is assigned to the direction of rotation at the wide-angle end position (29.0 mm) in the second embodiment

Table 22

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the center position (50.0 mm) in the second embodiment

Image magnification β _{K of} the lens units at the central position (50.0 mm) in the second embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the central position (50.0 mm) in the second embodiment

Slope dx / da of the focus cam at the middle position (50.0 mm) in the second embodiment

Conversion coefficient γ _a , which is assigned to the direction of rotation at the center position (50.0 mm) in the second embodiment

Table 23

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the telephoto end position (102.0 mm) in the second embodiment

Image magnification β _{K of} the lens units at the telephoto end position (102.0 mm) in the second embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the telephoto end position (102.0 mm) in the second embodiment

Slope dx / da of the focus cam at the telephoto end position (102.0 mm) in the second embodiment

Conversion coefficient γ _a , which is assigned to the direction of rotation at the center position (50.0 mm) in the second embodiment

As can be seen from Tables 21, 22 and 23, the conversion coefficient γ _x , which is assigned to the direction of the optical axis, increases for each focus length, but the slope (dx / da) of the focus cam decreases if the photo distance comes closer to the closest distance. Therefore, as can be seen from these tables, the conversion coefficient γ _{a associated with} the direction of rotation, which is defined as the product of the conversion coefficient γ _x and the slope (dx / da) of the focus cam, decreases when the photographer comes closer to the closest distance by the influence of the slope (dx / da) of the focus cam. Tables 21, 22 and 23 show the rate of change from the infinite focus position to the closest focus position of the conversion coefficient γ _a , which is associated with the direction of rotation. x0.48 at the wide-angle end position (F = 29.0), x0.42 at the middle position (F = 50.0) and x0.32 at the telephoto end position (F = 102.0). When the number N of divisions of the focus area is calculated with a change in the conversion coefficient γ _a in the second embodiment using the formula (a) and with that in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 is compared, the numbers N _W , N _M and N _{T of} the subdivisions at the wide-angle end position, the middle position and the telephoto end position each have the following values:
Embodiment of Japanese Patent Application Laid-Open No. 5-142475
N _W <9.3, N _M <10.1, N _T <8.1
Second embodiment
N _W <4.1, N _M <4.7, N _T <6.2.

Therefore, as from a comparison with the previously calculated values, though this embodiment has a larger zoom ratio than that in the embodiment Japanese Patent Application Laid-Open No. 5-142475 owns, understandable becomes small, the values of the number of subdivisions.

Also, as described above, in the second embodiment, since the rate of change of the conversion coefficient γ _{a assigned} to the direction of rotation becomes smaller than that of the conventional system, the value of the number N of divisions becomes small, the number of data of the conversion coefficient γ _a and the correction coefficient µ can be reduced and the storage capacity can be reduced.

Tables 24, 25 and 26 summarize the calculation results of the conversion coefficient K _a and the correction coefficient µ at the wide-angle end position (F = 29.0), the middle position (F = 50.0) and the telephoto end position (F = 102.0) according to the second embodiment. The arrangements of the tables and symbols are the same as those of the first embodiment. The position of the focusing lens in the first pair in the top two tables in each of tables 24, 25 and 26, ie in the third and fourth columns, is (R, ANGLE) = (0.0, 0.0) and it indicates that this position corresponds to the infinitely corresponding position. Similarly, the position of the focusing lens in the fourth pair in the lower two tables in each of tables 24, 25 and 26, ie in the ninth and 10th columns, (R, ANGLE) = (0.5, -9.5), and it indicates that this position corresponds to the closest position in focus (R = 0.5 m) corresponding position.

Table 24

Conversion coefficient K _a : (rs), γ _a : (r) assigned to the direction of rotation, and correction coefficient µ: (l) at the wide-angle end position (29.0 mm) of the second embodiment

f = 29.0 mm

Table 25

Conversion coefficient K _a : (rs), γ _a : (r) assigned to the direction of rotation, and correction coefficient µ: (l) at the center position (50.0 mm) of the second embodiment

f = 50.0 mm

Table 26

Conversion coefficient K _a : (rs), γ _a : (r) assigned the direction of rotation and correction coefficient µ: (l) at the telephoto end position (102.0 mm) of the second embodiment

f = 102.0 mm

The calculation results of the rate of change of K _a with respect to γ _a at the infinite focus arrangement and the closest focus arrangement at the wide-angle end position, the middle position and the telephoto end position in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 and the second embodiment of the present invention are as follows.

Embodiment of Japanese Patent Application Laid-Open No. 5-142475

Second embodiment

As described above, according to the second embodiment, since the rate of change of K _a with respect to γ _a is small compared to the conventional system, and the contribution of the correction term (ΔBf / µ) in K _a = γ _a (1 - ΔBf / µ) who can be reduced, an error in the conversion coefficient K _a , which is calculated using γ _a and µ, or in the actual lens drive amount Δa for focusing, if only a pair of a conversion coefficient value γ _a and a correction coefficient value µ is determined for a given lens arrangement area (e.g. the infinite arrangement area in focus).

Next, in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 and the second embodiment, when the lens drive amounts focusing from the infinite focus lens array to the closest object distance and focusing from the closest focus lens array to the infinite object distance Wide-angle end position, the middle position and the telephoto end position are calculated from Δa = ΔBf / γ _a (1 - ΔBf / µ) and errors are then calculated from the actual lens drive amounts, and the following values are obtained. It should be noted that the value of the correction coefficient µ under focusing from the infinite lens assembly in focus to the closest object distance takes a value at the object distance (POS-5) and the value of the correction coefficient µ under focusing from the closest, in focus lens arrangement to the infinite object distance takes a value at the object distance (POS-4).

Embodiment of Japanese Patent Application Laid-Open No. 5-142475

Second embodiment

Also, as described above, in the second embodiment, even if only a pair of a conversion coefficient value γ _a and a correction coefficient value µ are set for a given lens arrangement area, an error between the conversion coefficient K _a which is made up of γ _a and µ and that Linsenan drive amount Δa is calculated for focusing, small compared to the conventional system, and focusing can be realized with higher accuracy.

Table 27 summarizes the amount (ANGLE DA) of a rotation for focusing under one manual focusing using the focus cam (the middle table in Table 19) of the second embodiment, the amount X (mm) of a movement, and in the direction of the optical axis of the focusing lens unit according to the amount of rotation for focusing, and the shift amount Bf  (mm) of the imaging point when the amount (DX) of movement in the direction of the optical axis is given together.

It should be noted that the arrangement of the table and the symbols are the same as that are those in the first embodiment. The upper table in Table 27 summarizes the shift amount Bf of an imaging point corresponding to the photograph stands (R = 5.0, 3.0, 2.0,1.0, 0.7 and 0.5 m) in the respective zooming states the focus lengths (F = 29.0, 35.0, 50.0, 70.0, 85.0 and 102.0 mm) together and the middle table summarizes the values of the amount (ANGLE DA) of a rotation to the focus together to achieve an optimal, in-focus state with regard to the respective photographing distances are required. The table below summarizes the amounts (DX) of a movement, in the direction of the optical axis, of the respective Lens units corresponding to the amount (ANGLE DA) of a rotation to the focus assignment in relation to the respective focus lengths and photographing distances together.

Table 27

Displacement amount Bf (mm) of an imaging point and amount (DX) (mm) of a movement for focusing in the second embodiment

As can be seen from Table 27, according to the zoom lens the second embodiment, a so-called manual focusing who obtained because the shift amounts of the imaging point at the respective focus countries and photography distances are very small and they fall within the depth of the fo kus regardless of the zooming state and the photographing distance.

Third Embodiment

A zoom lens according to the third embodiment is a zoom lens which has an arrangement with four units, ie a positive, a negative, a positive and a negative lens unit and a focusing by a negative, second lens unit, as in the second Embodiment achieved. In this zoom lens, the rotation amount ratio (a _F / a _Z ) of the rotation amount for focusing from the infinite position in focus to the closest position in focus (R = 0.5 m) becomes the amount of rotation for zooming from the wide-angle end position (F = 29.0) to the telephoto end position (F = 102.0) so that it is -0.75.

Table 28 below summarizes various paraxial data of an optical system and Data for defining the shape of a focus cam according to the third embodiment shape together.

The upper table in Table 28 summarizes the focus lengths and the symmetry point interval data of the respective lens units of the optical system corresponding to the third Embodiment together. Therefore, this data is the same as different Pa raxial data (the upper table in Table 19) of the second embodiment.  

The middle table in Table 28 summarizes the wedge scan data when the shape of a focus cam in the second lens unit of the third embodiment a wedge function is expressed that corresponds to the angle of rotation of a rotatable Ob jective drum and the amount x of movement in the direction of the optical axis assigned.

Furthermore, the lower table in Table 28 summarizes the infinite positions in focus (positions corresponding to infinity) at the respective focus lengths (F = 29.0, 35.0, 50.0, 70.0, 85.0 and 102.0 mm) and the amounts of a rotation (amounts of one Rotation for focusing) focusing on respective photographing distances (R = 5.0, 3.0, 2.0, 1.0, 0.7 and 0.5 m) using the focus cam of the third embodiment together. In the lower table in Table 28, since the amount of rotation for zooming from the wide-angle end position (F = 29.0) to the telephoto end position (F = 102.0) is set to be 10.0, and the amount of rotation for focusing from the infinite focus position to the closest focus position (R = 0.5 m) is set to be -7.5, the rotation amount ratio (a _F / a _Z ) of the rotation amount to focus on Amount of rotation for zooming in the third embodiment -0.75.

Table 28

Third embodiment f = 29.0 to 102.0 (rotation amount ratio: a _F / a _Z = -0.75)

Focus lengths and symmetry point intervals of lens units of the third embodiment

Focus cam shape (wedge interpolation sampling point) according to the third embodiment

Amount of rotation for zooming and amount of rotation for focusing of the third embodiment

(Rotation amount ratio: a _F / a _Z = -0.75)

Table 29 below summarizes the numerical data values of the cams in the focus lens unit in the third embodiment, and this data by interpolation based on a wedge function based on the scan data of the Focus cams are calculated, which are summarized in the middle table in Table 28 are summarized. It should be noted that the meanings of the respective symbols in Ta 29 are the same as those according to the first embodiment.

Table 29

Numerical cam data values of a focusing lens unit in the third embodiment

The left table in Table 29 summarizes the numerical data values of the focus cam the third embodiment together and the right table in Table 29 summarizes the nu merit data values of the zoom compensation cam of this embodiment together. A value obtained by synthesizing the amounts (2) of a movement in the Direction of the optical axis in the numerical data values of the focus cam and the zoom compensation cam in the range of the amount of rotation (ANGLE = 0.0) on the amount of a rotation (ANGLE = 10.0) is correct the movement point of the second lens unit, which using the Pa raxial data is calculated in the upper table in Table 28.

Tables 30, 31 and 32 below summarize the amount DX (mm) of a movement for focusing in the direction of the optical axis of the focusing lens unit, the magnification β _{x of} the respective lens units, the conversion coefficient γ _x , the direction of the optical axis assigned, the slope (dx / da) of the focus cam and the conversion coefficient γ _a , which is assigned to the direction of rotation at the wide-angle end position (F = 29.0), the middle position (F = 50.0) and the telephoto end position (F = 102.0) is, according to the third embodiment, each together. Since different paraxial data are the same as those in the second embodiment, in each of the tables 30, 31 and 32, the amount DX (mm) of movement in the direction of the optical axis in the first table is the magnification β _{x of} the respective lens units in FIG of the second table and the conversion coefficient γ _{x assigned} to the direction of the optical axis of the focusing lens unit in the third table are the same as those in the second embodiment. On the other hand, although the values of the slope (dx / da) of the focus cam in the fourth table are larger compared to the second embodiment, the rate of change thereof becomes inversely small. Therefore, although the values of the conversion coefficient γ _{a associated} with the direction of rotation are large in the fifth table, the rate of change thereof is conversely small.

Table 30

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the wide-angle end position (29.0 mm) in the third embodiment

Image magnification β _{K of} the lens units at the wide-angle end position (29.0 mm) in the third embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the wide-angle end position (29.0 mm) in the third embodiment

Slope dx / da of the focus cam at the wide-angle end position (29.0 mm) in the third embodiment

Conversion coefficient γ _a , which is assigned to the direction of rotation at the wide-angle end position (29.0 mm) in the third embodiment

Table 31

Amount DX (mm) of a movement to focus in the direction of the optical axis at the center position (50.0 mm) in the third embodiment

Image magnification β _{K of} the lens units at the central position (50.0 mm) in the third embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the central position (50.0 mm) in the third embodiment

Slope dx / da of the focus cam at the middle position (50.0 mm) in the third embodiment

Conversion coefficient γ _a , which is assigned to the direction of rotation at the center position (50.0 mm) in the third embodiment

Table 32

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the telephoto end position (102.0 mm) in the third embodiment

Image magnification β _{K of} the lens units at the telephoto end position (102.0 mm) in the third embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the telephoto end position (102.0 mm) in the third embodiment

Slope dx / da of the focus cam at the telephoto end position (102.0 mm) in the third embodiment

Conversion coefficient γ _a , which is assigned to the direction of rotation at the telephoto end position (102.0 mm) in the third embodiment

As can be seen from Tables 30, 31 and 32, the conversion coefficient γ _x , which is assigned to the direction of the optical axis, increases for each focus length, but the slope (dx / da) of the focus cam decreases if the photo distance comes closer to the closest distance. Therefore, as can be seen from these tables, the conversion coefficient γ _{a associated with} the direction of rotation, which is defined as the product of the conversion coefficient γ _x and the slope (dx / da) of the focus cam, decreases when the photographer comes closer to the closest distance due to the influence of the slope (dx / da) of the focus cam. From Tables 30, 31 and 32, the rate of change from the infinite focus position to the closest focus position of the conversion coefficient γ _{a associated} with the direction of rotation is x0.58 at the wide-angle end position (F = 29.0), x0.52 at the middle position (F = 50.0) and x0.39 at the telephoto end position (F = 102.0). When the number N of divisions of the focus area under a change in the conversion coefficient γ _a in the third embodiment is calculated using the formula (a) and compared with that in the second embodiment, the numbers have N _W , N _M and N _{T of} the subdivisions at the wide-angle end position, the middle position and the telephoto end position each have the following values:

Second embodiment (rotation angle ratio: -0.95)
N _W <4.1, N _M <4.7, N _T <6.2,
Third embodiment (rotation angle ratio: -0.75)
N _W <3.0, N _M <3.6, N _T <5.2.

As can be seen from the comparison above, since the rotation amount ratio between the amount of a rotation for zooming and the rotation amount to focus in the third embodiment (-0.75) closer to the upper one Limit of the state formula (2) than in the second embodiment (-0.95) is the who te of the numbers N of the divisions smaller than those in the second Embodiment.

As described above, if the paraxial data remains the same, if the rotation amount ratio (a _F / a _Z ) between the amount of rotation for zooming and the amount of rotation for focusing comes closer to the upper limit of the state formula (2), that Rate of change of the conversion coefficient γ _{a associated with} the direction of rotation is small, and the number N of divisions of the focus area can be reduced. However, is can be seen from the comparison with the second embodiment, when the change rate of the con version factor γ _a, which is assigned to the direction of rotation is smaller, the value of the conversion coefficient γ _a itself, the net the direction of rotation zugeord is bigger. Therefore, if the rate of change (γ _aR / γ _aO ) of the conversion coefficient γ _a is set to exceed the upper limit of the state formula (3), the sensitivity requirement (dBf / da) that the movement in the direction of rotation is made is assigned, more precisely and to 99999 00070 552 001000280000000200012000285919988800040 0002019530770 00004 99880ne change in the imaging point due to a small error factor in the direction of rotation becomes large, consequently disrupting an accurate auto-focus.

Tables 33, 34 and 35 summarize the calculation results of the conversion coefficient K _a and the correction coefficient µ at the wide-angle end position (F = 29.0), the middle position (F = 50.0) and the telephoto end position (F = 102.0) according to the third embodiment. The arrangements of the tables and symbols are the same as those of the second embodiment. The position of the focusing lens in the first pair in the top two tables 1 in each of tables 33, 34 and 35, ie in the third and fourth columns, is (R, ANGLE) = (0.0, 0.0) and indicates that this position corresponds to the infinitely corresponding position. Similarly, the position of the focusing lens in the fourth pair in the lower two tables in each of tables 33, 34 and 35, ie in the ninth and tenth columns, (R, ANGLE) = (0.5, -7.5), and it indicates that this position corresponds to the closest position in focus (R = 0.50 m) corresponding position.

Table 33

Conversion coefficient K _a : (rs), γ _a : (r) assigned to the direction of rotation, and correction coefficient µ: (l) at the wide-angle end position (29.0 mm) of the third embodiment

f = 29.0 mm

Table 34

Conversion coefficient K _a : (rs), γ _a : (r) assigned to the direction of rotation, and correction coefficient µ: (l) at the central position (50.0 mm) of the third embodiment

f = 50.0 mm

Table 35

Conversion coefficient K _a : (rs), γ _a : (r) assigned the direction of rotation and correction coefficient µ: (l) at the telephoto end position (102.0 mm) of the third embodiment

f = 102.0 mm

The calculation results of the change rate of K _a with respect to γ _a at the infinite focus arrangement and the closest focus arrangement at the wide-angle end position, the center position and the telephoto end position in the second and third embodiments are as follows.

Second embodiment

Third embodiment

As described above, in the third embodiment, since the rate of change of K _a with respect to γ _{a is} small compared to the second embodiment, the contribution of the correction term (ΔBf / µ) in K _a = γ _a (1 - ΔBf / µ) can still be reduced.

Error in the lens drive amounts focusing from the infinite ones in the Focus lens arrangement to the closest object distance and under focus sation from the closest lens arrangement in focus to the infinite Chen object distance at the wide-angle end position, the middle position and the telephoto end positions in the third embodiment are calculated and with those of the compared second embodiment. It should be noted that the values of the correction coefficients µ in the infinite and the closest Lin in focus each arrangement values at the object distances (POS-5) and (POS-4) as represent assume sentative values.  

Second embodiment

Third embodiment

As described above, only by pairing a conversion coefficient value γ _a and a correction coefficient value µ by bringing the rotation amount ratio (a _F / a _Z ) between the amount of rotation for zooming and the amount of rotation for focusing, can a predetermined lens arrangement area be close to that upper limit of the state formula (2), an error of the lens driving amount Δ for focusing calculated by the pair of γ _a and µ can be reduced, and focusing can be realized with higher accuracy.

Table 36 summarizes the amount (ANGLE DA) of a rotation for focusing under one manual focusing using the focus cam (the middle table in Table 28) of the third embodiment, the amount X (mm) of a movement, namely in the direction of the optical axis of the focusing lens unit accordingly the amount of rotation for focusing, and the shift amount Bf (mm) of Imaging point when the amount (DX) of movement in the direction of the optical Axis is given together.  

It should be noted that the arrangement of the table and the symbols are the same as that are those in the second embodiment. The upper table in Table 36 summarizes the shift amount Bf of the imaging point corresponding to the photograph stands (R = 5.0, 3.0, 2.0, 1.0, 0.7 and 0.5 m) in the respective zooming states the focus lengths (F = 29.0, 35.0, 50.0, 70.0, 85.0 and 102.0 mm) together and the middle table summarizes the values of the amount (ANGLE DA) of a rotation to the focus together to achieve an optimal, in-focus state with regard to the respective photographing distances are required. The table below summarizes the amounts (DX) of a movement in the direction of the optical axis of the respective Lens units corresponding to the amount (ANGLE DA) of a rotation to the focus assignment in relation to the respective focus lengths and photographing distances together.

Table 36

Displacement amount Bf (mm) of an imaging point and amount (DX) (mm) of a movement for focusing in the third embodiment

As can be seen from Table 36, a so-called manual focusing can be obtained because the amounts of displacement of the imaging point at the respective focus lengths and photographing distances are very small, especially if the rotation amount ratio (a _F / a _Z ) between the amount of rotation to Zooming and changing the amount of rotation for focusing.

Fourth Embodiment

The fourth embodiment is directed to a zoom lens having an arrangement with four units, ie a positive, a negative, a positive and a positive lens unit, and focusing by a negative, second lens unit. In this zoom lens, the rotation amount ratio (a _F / a _Z ) of the rotation amount for focusing from the infinite position in focus to the closest position in focus (R = 0.5 m) becomes the amount of rotation Zoom from the wide-angle end position (F = 28.8) to the telephoto end position (F = 82.5) set to be -0.9.

Table 37 below summarizes various paraxial data of an optical system and Data for defining the shape of a focus cam according to the fourth embodiment shape together.

The upper table in Table 37 summarizes the focus lengths and the symmetry point interval data of the respective lens units of the optical system according to the fourth  Embodiment in association with six zooming states (focus lengths F = 28.8, 35.0, 50.0, 60.0, 70.0 and 82.5 mm) together.

The middle table in Table 37 summarizes the wedge scan data when the shape a focus cam in the second lens unit of the fourth embodiment, which is for Focusing is used, expressed by a wedge function, the angle a a rotation of a rotatable lens drum and the amount x of a movement in is assigned to the direction of the optical axis.

Furthermore, the lower table in Table 37 summarizes the infinite positions in focus (positions corresponding to infinity) at the respective focus lengths (F = 28.8, 35.0, 50.0, 60.0, 70.0 and 82.5 mm) and the amounts of a rotation (amounts of one Rotation for focusing) focusing on respective photographing distances (R = 5.0, 3.0, 2.0, 1.0, 0.7 and 0.5 m) using the focus cam of the fourth embodiment together. In the lower table in Table 37, since the amount of rotation for zooming from the wide-angle end position (R = 28.8) to the telephoto end position (F = 82.5) is set to be 10.0, and the amount of rotation for focusing is of the infinite focus position to the closest focus position (R = 0.5 m) is set to be -9.0, the rotation amount ratio (a _F / a _Z ) of the rotation amount for focusing to the amount a rotation for zooming in the fourth embodiment -0.90.

Table 37

Fourth embodiment f = 28.8 to 82.5 (rotation amount ratio: a _F / a _Z = -0.9)

Focus lengths and symmetry point intervals of lens units of the fourth embodiment

Focus cam shape (wedge interpolation sampling point) according to the fourth embodiment

Amount of rotation for zooming and amount of rotation for focusing the fourth embodiment

(Rotation amount ratio: a _F / a _Z = -0.9)

Table 38 below summarizes the numerical data values of the cams in the focus end lens unit in the fourth embodiment, this data by interpolation based on a wedge function based on the scan data of the Focus cams are calculated, which are summarized in the middle table in Table 37 are summarized. It should be noted that the meanings of the respective symbols in Ta belle 38 are the same as those according to the first embodiment.

Table 38

Numerical cam data values of a focusing lens unit in the fourth embodiment

The left table in Table 38 summarizes the numerical data values of the focus cam the fourth embodiment together and the right table in Table 38 summarizes the numerical data values of the zoom compensation cam of this embodiment together. A value obtained by synthesizing the amounts (2) of a movement in the Direction of the optical axis in the numerical data values of the focus cam and the zoom compensation cam in the range of the amount of rotation (ANGLE = 0.0) on the amount of a rotation (ANGLE = 10.0) is correct the movement point of the second lens unit, which using the Pa raxial data is calculated in the upper table in Table 37.

Tables 39, 40 and 41 below summarize the amount DX (mm) of a movement for focusing in the direction of the optical axis of the focusing lens unit, the magnification β _{x of} the respective lens units, the conversion coefficient γ _x , the direction of the optical axis is assigned, the slope (dx / da) of the focus cam and the conversion coefficient γ _a , which corresponds to the direction of a conversion coefficient γ _x , which is assigned to the direction of the optical axis, the slope (dx / da) of the focus cam and the Conversion coefficients γ _a , which is assigned to the direction of rotation at the wide-angle end position (F = 28.8), the middle position (F = 50.0) and the telephoto end position (F = 82.5), according to the fourth embodiment together in each case. The arrangements of the respective tables and the meanings of the symbols are the same as those of the first embodiment.

Table 39

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the wide-angle end position (28.8 mm) in the fourth embodiment

Image magnification β _{K of} the lens units at the wide-angle end position (28.8 mm) in the fourth embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the wide-angle end position (28.8 mm) in the fourth embodiment

Slope dx / da of the focus cam at the wide-angle end position (28.8 mm) in the fourth embodiment

Conversion coefficient γ _{a assigned} to the direction of rotation at the wide-angle end position (28.8 mm) in the fourth embodiment

Table 40

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the center position (50.0 mm) in the fourth embodiment

Image magnification β _{K of} the lens units at the central position (50.0 mm) in the fourth embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the central position (50.0 mm) in the fourth embodiment

Slope dx / da of the focus cam at the central position (50.0 mm) in the fourth embodiment

Conversion coefficient γ _a , which is assigned to the direction of rotation at the center position (50.0 mm) in the fourth embodiment

Table 41

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the telephoto end position (82.5 mm) in the fourth embodiment

Image magnification β _{K of} the lens units at the telephoto end position (82.5 mm) in the fourth embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the telephoto end position (82.5 mm) in the fourth embodiment

Slope dx / da of the focus cam at the telephoto end position (82.5 mm) in the fourth embodiment

Conversion coefficient γ _{a associated with} the direction of rotation at the telephoto end position (82.5 mm) in the fourth embodiment

As can be seen from Tables 39, 40 and 41, the conversion coefficient γ _{x associated with} the direction of the optical axis increases with each focus length, but the slope (dx / da) of the focus cam decreases if the Photo distance comes closer to the closest distance. Therefore, as can be seen from these tables, the conversion coefficient γ _a , which is assigned to the direction of a rotation and which is defined as the product of the conversion coefficient γ _x and the slope (dx / da) of the focus cam, decreases when the photographer comes closer to the closest distance due to the influence of the slope (dx / da) of the focus cam. From Tables 39, 40, and 41, the rate of change from the infinite focus position to the closest focus position of the conversion coefficient γ _{a associated} with the direction of rotation is x0.49 at the wide-angle end position (F = 28.8), x0.44 at the middle position (F = 50.0) and x0.35 at the telephoto end position (F = 82.5). When the number N of divisions of the focus area is calculated with a change in the conversion coefficient γ _a in the fourth embodiment using the formula (a) and that in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 is compared, the numbers N _W , N _M and N _{T of} the subdivisions at the wide-angle end position, the middle position and the telephoto end position each have the following values:

Embodiment of Japanese Patent Application Laid-Open No. 5-142475
N _W <9.3, N _M <10.1, N _T <8.1
Fourth embodiment
N _W <3.9, N _M <4.5, N _T <5.8.

Also, as described above, in the fourth embodiment, since the rate of change of the conversion coefficient γ _{a assigned} to the direction of rotation is smaller than that in the conventional system, the values of the numbers N of the divisions become small. For this reason, the number of data of the conversion coefficient γ _a and the correction coefficient µ can be reduced and the storage capacity can be reduced.

Tables 42, 43 44 summarize the calculation results of the conversion coefficient K _a and the correction coefficient µ at the wide-angle end position (F = 28.8), the middle position (F = 50.0) and the telephoto end position (F = 82.5) according to the fourth embodiment. The arrangements of the tables and symbols are the same as those of the first embodiment. The position of the focusing lens in the first pair in the top two tables in each of tables 42, 43 and 44., ie in the third and fourth columns, is (R, ANGLE) = (0.0, 0.0), and indicates that this position corresponds to the infinitely corresponding position. Similarly, the position of the focusing lens in the fourth pair in the lower two tables in each of tables 42, 43 and 44, that is, in the ninth and tenth columns, (R, ANGLE) = (0.5, -9.0) and them indicates that this position corresponds to the closest position in focus (R = 0.50 m) corresponding position.

Table 42

Conversion coefficient K _a : (rs), γ _a : (r) assigned to the direction of rotation, and correction coefficient µ: (l) at the wide-angle end position (28.8 mm) of the fourth embodiment

f = 28.8 mm

Table 43

Conversion coefficient K _a : (rs), γ _a : (r) assigned to the direction of rotation, and correction coefficient µ: (l) at the central position (50.0 mm) of the fourth embodiment

f = 50.0 mm

Table 44

Conversion coefficient K _a : (rs), γ _a : (r) assigned the direction of rotation and correction coefficient µ: (l) at the telephoto end position (82.5 mm) of the fourth embodiment

f = 82.5 mm

The calculation results of the change rate of K _a with respect to γ _a at the infinite focus arrangement and the closest focus arrangement at the wide-angle end position, the middle position and the telephoto end position in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 and in the fourth embodiment of the present invention are as follows.

Embodiment of Japanese Patent Application Laid-Open No. 5-142475

Fourth embodiment

As described above, also in the fourth embodiment, since the rate of change of K _{a in} γ _{a is} small compared to the conventional system, the contribution of the correction term (ΔBf / µ) in K _a = γ _a (1 - ΔBf / µ) continues to be reduced. For this reason, an error of the conversion coefficient K _a calculated based on γ _a and µ, or an error from the actual lens driving amount Δa obtained when only a pair of a conversion coefficient value γ _a and a correction coefficient value µ is set, be reduced.

Next, in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 and the fourth embodiment of the present invention when the lens driving amounts are focused by focusing from an infinite focal lens array to the closest object distance and focusing from the closest focal lens array to the infinite object distance below Wide-angle end position, the middle position and the telephoto end position are calculated from Δa = ΔBf / γ _a (1 - ΔBf / µ), and errors from the actual lens drive amounts are then calculated, whereby the following values are obtained. It should be noted that the value of the correction coefficient µ while focusing from the infinite lens arrangement in focus to the closest object distance takes a value at the object distance (POS-5) and the value of the correction coefficient µ while focusing from the closest one lens arrangement in focus to the infinite object distance assumes a value at the object distance (POS-4).

Embodiment of Japanese Patent Application Laid-Open No. 5-142475

Fourth embodiment

Also, as described above, in the fourth embodiment, even if only a pair of a conversion coefficient value γ _a and a correction coefficient value µ are set for a given lens arrangement range, an error between the conversion coefficient K _a which is made up of γ _a and µ and that Linsenan drive amount Δa is calculated for focusing, small compared to the conventional system, and focusing can be realized with higher accuracy.

Table 45 summarizes the amount (ANGLE DA) of a rotation for focusing under one manual focusing using the focus cam (the middle table in  Table 37) of the fourth embodiment. the amount X (mm) of a movement, namely in the direction of the optical axis of the focusing lens unit accordingly the amount of rotation for focusing, and the shift amount Bf (mm) of Imaging point when the amount (DX) of movement in the direction of the optical Axis is given together.

It should be noted that the arrangement of the table and the reference symbols are the same like those in the first embodiment. The upper table in Table 45 summarizes the shift amount Bf of an imaging point according to the photographers distances (R = 5.0, 3.0, 2.0,1.0, 0.7 and 0.5 m) in the respective zooming states the focus lengths (F = 28.8, 35.0, 50.0, 60.0, 70.0 and 82.5 mm) together and the mean The table below summarizes the values of the amount (ANGLE DA) of a rotation for focusing together, to achieve an optimal, in-focus state of the respective photographing distances are required. The table below summarizes the Amounts (DX) of a movement in the direction of the optical axis, the respective Lin units corresponding to the amount (ANGLE DA) of a rotation for focusing in Allocation to the respective focus lengths and photographing distances together.

Table 45

Displacement amount Bf (mm) of an imaging point and amount (DX) (mm) of a movement for focusing in the fourth embodiment

As can be seen from Table 45, according to the zoom lens the fourth embodiment, a so-called manual focusing can be obtained since the amounts of displacement of the imaging point at the respective focus lengths and Photography distances are very small and they do not fall within the depth of focus depending on the zooming state and the photographing distance.

Fifth Embodiment

The fifth embodiment is directed to a zoom lens which has an arrangement with five units, ie a positive, a negative, a positive, a negative and a positive lens unit, and a focusing by means of a negative, second lens unit. In this zoom lens, the rotation amount ratio (a _F / a _Z ) of the rotation amount for focusing from the infinite position in focus to the closest position in focus (R = 0.8 m) becomes the amount of rotation for zooming from the wide-angle end position (F = 28.7) to the telephoto end position (F = 131.0) so that it is -0.85.

Table 46 below summarizes various paraxial data of an optical system and Data for defining the shape of a focus cam according to the fifth embodiment shape together.

The upper table in Table 46 summarizes the focus lengths and the symmetry point interval data of the respective lens units of the optical system according to the fifth Embodiment in association with six zooming states (focus lengths F = 28.7, 35.0, 50.0, 70.0, 105.0 and 131.0 mm) together.  

The middle table in Table 46 summarizes the wedge scan data when the shape of a focus cam in the second lens unit of the fifth embodiment used for focusing is expressed by a wedge function that corresponds to the Angle of rotation of a rotatable lens drum and the amount x of a movement is assigned in the direction of the optical axis.

Furthermore, the lower table in Table 46 summarizes the infinite positions in focus (positions corresponding to infinity) at the respective focus lengths (F = 28.7, 35.0, 50.0, 70.0, 105.0 and 131.0 mm) and the amounts of a rotation (amounts a rotation for focusing) focusing on respective photographing distances (R = 5.0, 3.0, 2.0, 1.5, 1.0 and 0.8 m) using the focus cam of the fifth embodiment. In the lower table in Table 46, since the amount of rotation for zooming from the wide-angle end position (F = 28.7) to the telephoto end position (F = 131.0) is set to be 10.0, and the amount of rotation for focusing is the infinite position in focus to the closest position in focus (R = 0.8 m) is set to be -8.5, the rotation amount ratio (a _F / a _Z ) of the rotation amount for focusing to that Amount of rotation for zooming in the fifth embodiment -0.85.

Table 46

Fifth embodiment f = 28.7 to 131.0 (rotation amount ratio: a _F / a _Z = -0.85)

Focus lengths and symmetry point intervals of lens units of the fifth embodiment

Focus cam shape (wedge interpolation sampling point) according to the fifth embodiment

Amount of rotation for zooming and amount of rotation for focusing of the fifth embodiment

(Rotation amount ratio: a _F / a _Z = -0.85)

focusing lens unit together in the fifth embodiment, these Data by interpolation based on a wedge function based on the sample data of the focus cam are calculated, which are summarized in the middle table in Table 46 are quantified. It should be noted that the meanings of the respective reference sym bole in Table 47 the same as those according to the first embodiment are.

Table 47

Numerical cam data values of a focusing lens unit in the fifth embodiment

The left table in Table 47 summarizes the numerical data values of the focus cam the fifth embodiment together and the right table in Table 47 summarizes the numerical data values of the zoom compensation cam of this embodiment together. A value obtained by synthesizing the amounts (2) of a movement in the Direction of the optical axis in the numerical data values of the focus cam and the zoom compensation cam in the range of the amount of rotation (ANGLE = 0.0) on the amount of a rotation (ANGLE = 10.0) is correct the movement point of the second lens unit, which using the Pa raxial data is calculated in the upper table in Table 46.

Tables 48, 49 and 50 below summarize the amount DX (mm) of a movement for focusing in the direction of the optical axis of the focusing lens unit, the image magnifications β _{x of} the respective lens units, the conversion coefficient γ _x , the direction of the optical axis assigned, the slope (dx / da) of the focus cam and the conversion coefficient γ _a , which is assigned to the direction of a rotation at the wide-angle end position (F = 28.7), the middle position (F = 70.0) and the telephoto end position (F = 131.0) is together according to the fifth embodiment. The arrangements of the respective tables and the meanings of the symbols are the same as those of the first embodiment.

Table 48

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the wide-angle end position (28.7 mm) in the fifth embodiment

Image magnification β _{K of} the lens units at the wide-angle end position (28.7 mm) in the fifth embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the wide-angle end position (28.7 mm) in the fifth embodiment

Slope dx / da of the focus cam at the wide-angle end position (28.7 mm) in the fifth embodiment

Conversion coefficient γ _a , which is assigned to the direction of rotation at the wide-angle end position (28.7 mm) in the fifth embodiment

Table 49

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the center position (70.0 mm) in the fifth embodiment

Image magnification β _{K of} the lens units at the central position (70.0 mm) in the fifth embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the center position (70.0 mm) in the fifth embodiment

Slope dx / da of the focus cam at the central position (70.0 mm) in the fifth embodiment

Conversion coefficient γ _{a assigned} to the direction of rotation at the center position (70.0 mm) in the fifth embodiment

Table 50

Amount DX (mm) of a movement to focus in the direction of the optical axis at the telephoto end position (131.0 mm) in the fifth embodiment

Image magnification β _{K of} the lens units at the telephoto end position (131.0 mm) in the fifth embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the telephoto end position (131.0 mm) in the fifth embodiment

Slope dx / da of the focus cam at the telephoto end position (131.0 mm) in the fifth embodiment

Conversion coefficient γ _{a assigned} to the direction of rotation at the telephoto end position (131.0 mm) in the fifth embodiment

As can be seen from Tables 48, 49 and 50, the conversion coefficient γ _x , which is assigned to the direction of the optical axis, increases with each focus length, but the slope (dx / da) of the focus cam decreases if the photo distance comes closer to the closest distance. Therefore, as can be seen from these tables, the conversion coefficient γ _a , which is assigned to the direction of a rotation and which is defined as the product of the conversion coefficient γ _x and the slope (dx / da) of the focus cam, decreases when the photographer comes closer to the closest distance due to the influence of the slope (dx / da) of the focus cam. From Tables 48, 49 and 50, the rate of change from the infinite, in-focus position to the closest, in-focus position of the conversion coefficient γ _{a associated} with the direction of rotation is x0.47 at the wide-angle end position (F = 28.7), x0.38 at the middle position (F = 70.0) and x0.37 at the telephoto end position (F = 131.0). When the number N of divisions of the focus area is calculated with a change in the conversion coefficient γ _a in the fifth embodiment using the formula (a) and that in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 is compared, the numbers N _W , N _M and N _{T of} the subdivisions at the wide-angle end position, the middle position and the telephoto end position each have the following values:
Embodiment of Japanese Patent Application Laid-Open No. 5-142475
N _W <9.3, N _M <10.1, N _T <8.1
Fifth embodiment
N _W <4.2, N _M <5.3, N _T <5.5.

Therefore, although the zoom lens of this embodiment becomes larger Zoom ratio than that in the embodiment of the Japanese disclosed Patent application No. 5-142475 has the values of the numbers N of divisions conversely lowered.

Also, as described above, in the fifth embodiment, since the rate of change of the conversion coefficient γ _{a assigned} to the direction of rotation is smaller than that in the conventional system, the values of the numbers N of the divisions become small. For this reason, the number of data of the conversion coefficient γ _a and the correction coefficient µ can be reduced and the storage capacity can be reduced.

Tables 51, 52 and 53 summarize the calculation results of the conversion coefficient K _a and the correction coefficient µ at the wide-angle end position (F = 28.7), the middle position (F = 70.0) and the telephoto end position (F = 131.0) according to the fifth embodiment. The arrangements of the tables and symbols are the same as those of the first embodiment. The position of the focusing lens in the first pair in the top two tables, in each of tables 51, 52 and 53, ie in the third and fourth columns, is (R, ANGLE) = (0.0, 0.0), and indicates that this position corresponds to the infinitely corresponding position. Similarly, the position of the focusing lens in the fourth pair in the lower two tables in each of Tables 51, 52 and 53, ie in the ninth and 10th columns, (R, ANGLE) = (0.8, -8.5), and it indicates that this position corresponds to the closest position in focus (R = 0.80 m) corresponding position.

Table 51

Conversion coefficient K _a : (rs), γ _a : (r) assigned to the direction of rotation, and correction coefficient µ: (l) at the wide-angle end position (28.7 mm) of the fifth embodiment

f = 28.7 mm

Table 52

Conversion coefficient K _a : (rs), γ _a : (r) assigned to the direction of rotation, and correction coefficient µ: (l) at the central position (70.0 mm) of the fifth embodiment

f = 70.0 mm

Table 53

Conversion coefficient K _a : (rs), γ _a : (r) assigned to the direction of rotation and correction coefficient µ: (l) at the telephoto end position (131.0 mm) of the fifth embodiment

f = 131.0 mm

The calculation results of the change rate of K _a with respect to γ _a at the infinite focus position and the closest focus position at the wide-angle end position, the center position and the telephoto end position in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 and in the fifth embodiment of the present invention are as follows.

Embodiment of Japanese Patent Application Laid-Open No. 5-142475

Fifth embodiment

Also, as described above, in the fifth embodiment, since the rate of change of K _{a in} γ _{a is} small compared to the conventional system, the contribution of the correction term (ΔBf / µ) in K _a = γ _a (1 - ΔBf / µ) continues to be reduced. For this reason, an error of the conversion coefficient K _a calculated based on γ _a and µ, or an error from the actual lens driving amount Δa obtained when only a pair of a conversion coefficient value γ _a and a correction coefficient value µ are set, be reduced.

Next, in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 and the fifth embodiment of the present invention, the lens drive amounts focusing from an infinite focus lens array to the closest object distance and focusing from the closest focus lens array to the infinite object distance at the wide-angle end position The center position and the telephoto end position are calculated from Δa = ΔBf / γ _a (1 - ΔBf / µ), and errors from the actual lens drive amounts are then calculated, with the following values being obtained.

It should be noted that the value of the correction coefficient u focusing on the infinite, in focus lens arrangement to the closest Ob object distance assumes a value at the object distance (POS-5) and the value of the cor correction coefficients µ focusing from the closest one in focus Lens arrangement to the infinite object distance a value at the object distance (POS-4) assumes.

Embodiment of Japanese Patent Application Laid-Open No. 5-142475

Fifth embodiment

Also, as described above, in the fifth embodiment, even if only a pair of a conversion coefficient value γ _a and a correction coefficient value µ are set for a given lens arrangement range, an error between the conversion coefficient K _a that is made up of γ _a and µ and that Lens drive amount Δa is calculated for focusing, small compared to the conventional system, and focusing can be realized with higher accuracy.

Table 54 summarizes the amount (ANGLE DA) of a rotation for focusing under one manual focusing using the focus cam (the middle table in Table 46) of the fifth embodiment, the amount X (mm) of a movement, namely in the direction of the optical axis of the focusing lens unit accordingly the amount of rotation for focusing, and the shift amount Bf (mm) of Imaging point when the amount (DX) of movement in the direction of the optical Axis is given together.

Note that the arrangement of the table and the reference symbols are the same like those in the first embodiment. The upper table in Table 54 summarizes the shift amount Bf of an imaging point according to the photographers distances (R = 5.0, 3.0, 2.0, 1.5, 1.0 and 0.8 m) in the respective zooming states the focus lengths (F = 28.7, 35.0, 50.0, 70.0, 105.0 and 131.0 mm) together and the middle table summarizes the values of the amount (ANGLE DA) of a rotation to the focus together to achieve an optimal, in-focus state with regard to the respective photographing distances are required. The table below summarizes the amounts (DX) of a movement, in the direction of the optical axis, of the respective Lens units corresponding to the amount (ANGLE DA) of a rotation to the focus assignment in relation to the respective focus lengths and photographing distances together.

Table 54

Displacement amount Bf (mm) of an imaging point and amount (DX) (mm) of a movement for focusing in the fifth embodiment

As can be seen from Table 54, according to the zoom lens the fifth embodiment, a so-called manual focusing can be obtained, since the amounts of displacement of the imaging point at the respective focus lengths and Photography distances are very small and they do not fall within the depth of focus depending on the zooming state and the photographing distance.

Sixth Embodiment

The sixth embodiment is directed to a zoom lens which has an arrangement with four units, ie a positive, a negative, a positive, and a positive lens unit, and a focusing by means of a negative, second lens unit, is sufficient. In this zoom lens, the rotation amount ratio (a _F / a _Z ) of the rotation amount for focusing from the infinite position in focus to the closest position in focus (R = 0.5 m) becomes the amount of rotation Zooming from the wide-angle end position (F = 28.8) to the telephoto end position (F = 103.0) set so that it is -0.80.

Table 55 below summarizes various paraxial data of an optical system and Data for defining the shape of a focus cam according to the sixth embodiment form together.

The upper table in Table 55 summarizes the focus lengths and the symmetry point interval data of the respective lens units of the optical system corresponding to the sixth  Embodiment in association with six zooming states (focus lengths F = 28.8, 35.0, 50.0, 70.0, 85.0 and 103.0 mm) together.

The middle table in Table 55 summarizes the wedge scan data when the shape of a focus cam in the second lens unit of the sixth embodiment a wedge function is expressed that corresponds to the angle of rotation of a rotatable Ob jective drum and the amount x of movement in the direction of the optical axis assigned.

Furthermore, the table below in Table 55 summarizes the infinite positions in focus (positions corresponding to infinity) at the respective focus lengths (F = 28.8, 35.0, 50.0, 70.0, 85.0 and 103.0 mm) and the amounts of a rotation (amounts of one Rotation for focusing) focusing on respective photographing distances (R = 5.0, 3.0, 2.0, 1.0, 0.7 and 0.5 m) using the focus cam of the sixth embodiment together. In the lower table in Table 55, since the amount of a rotation for zooming from the wide-angle end position (F = 28.8) to the telephoto end position (F = 103.0) is set to be 10.0, and the amount of a rotation to Focusing from the infinite position in focus to the closest position in focus (R = 0.5 m) is set to be -8.0, the rotation amount ratio (a _F / a _Z ) of the rotation amount for focusing to the amount of rotation for zooming in the sixth embodiment -0.80.

Table 55

Sixth embodiment f = 28.8 to 103.0 (rotation amount ratio: a _F / a _Z = -0.8)

Focus lengths and symmetry point intervals of lens units of the sixth embodiment

Focus cam shape (wedge interpolation sampling point) according to the sixth embodiment

Rotation amount for zooming and rotation amount for focusing in the sixth embodiment

(Rotation ratio: a _F / a _Z = -0.8)

Table 56 below summarizes the numerical data values of the cams in the focus end lens unit in the sixth embodiment, this data by interpolation based on a wedge function based on the scan data of the Focus cams are calculated, which are summarized in the middle table in Table 55 are summarized. It should be noted that the meanings of the respective symbols in Ta belle 56 are the same as those according to the first embodiment.

Table 56

Numerical cam data values of a focusing lens unit in the sixth embodiment

The left table in Table 56 summarizes the numerical data values of the focus cam the sixth embodiment together and the right table in Table 56 summarizes the numerical data values of the zoom compensation cam of this embodiment together. A value obtained by synthesizing the amounts (2) of a movement in the Direction of the optical axis in the numerical data values of the focus cam and the zoom compensation cam in the range of the amount of rotation (ANGLE = 0.0) on the amount of a rotation (ANGLE = 10.0) is correct the movement point of the second lens unit, which using Par axial data in the upper table in Table 55 is calculated.

Tables 57, 58 and 59 below summarize the amount DX (mm) of a movement for focusing in the direction of the optical axis of the focusing lens unit, the magnification β _{x of} the respective lens units, the conversion coefficient γ _x , the direction of the optical axis assigned, the slope (dx / da) of the focus cam and the conversion coefficient γ _a , which is assigned to the direction of a rotation at the wide-angle end position (F = 28.8), the middle position (F = 50.0) and the telephoto end position (F = 103.0) is together according to the sixth embodiment. The arrangements of the respective tables and the meanings of the symbols are the same as those of the first embodiment.

Table 57

Amount DX (mm) of a movement to focus in the direction of the optical axis at the wide-angle end position (28.8 mm) in the sixth embodiment

Image magnification β _{K of} the lens units at the wide-angle end position (28.8 mm) in the sixth embodiment

Conversion coefficient γ _{x associated with} the direction of the optical axis at the wide-angle end position (28.8 mm) in the sixth embodiment

Slope dx / da of the focus cam at the wide-angle end position (28.8 mm) in the sixth embodiment

Conversion coefficient γ _{a assigned} to the direction of rotation at the wide-angle end position (28.8 mm) in the sixth embodiment

Table 58

Amount DX (mm) of a movement to focus in the direction of the optical axis at the center position (50.0 mm) in the sixth embodiment

Image magnification β _{K of} the lens units at the central position (50.0 mm) in the sixth embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the center position (50.0 mm) in the sixth embodiment

Slope dx / da of the focus cam at the central position (50.0 mm) in the sixth embodiment

Conversion coefficient γ _{a assigned} to the direction of rotation at the center position (50.0 mm) in the sixth embodiment

Table 59

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the telephoto end position (103.0 mm) in the sixth embodiment

Image magnification β _{K of} the lens units at the telephoto end position (103.0 mm) in the sixth embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the telephoto end position (103.0 mm) in the sixth embodiment

Slope dx / da of the focus cam at the telephoto end position (103.0 mm) in the sixth embodiment

Conversion coefficient γ _{a assigned} to the direction of rotation at the telephoto end position (103.0 mm) in the sixth embodiment

As can be seen from Tables 57, 58 and 59, the conversion coefficient γ _x , which is assigned to the direction of the optical axis, increases for each focus length, but the slope (dx / da) of the focus cam decreases if the photo distance comes closer to the closest distance. Therefore, as can be seen from these tables, the conversion coefficient γ _a , which is assigned to the direction of a rotation and which is defined as the product of the conversion coefficient γ _x and the slope (dx / da) of the focus cam, decreases when the photographer comes closer to the closest distance due to the influence of the slope (dx / da) of the focus cam. From Tables 57, 58 and 59, the rate of change from the infinite focus position to the closest focus position of the conversion coefficient γ _{a associated} with the direction of rotation is x0.49 at the wide-angle end position (F = 28.8), x0.44 at the middle position (F = 50.0) and x0.31 at the telephoto end position (F = 103.0). When the number N of divisions of the focus area under a change in the conversion coefficient γ _a in the sixth embodiment is calculated using the formula (a) and with that in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 is compared, the numbers N _W , N _M and N _{T of} the subdivisions at the wide-angle end position, the middle position and the telephoto end position each have the following values:
Embodiment of Japanese Patent Application Laid-Open No. 5-142475
N _W <9.3, N _M <10.1, N _T <8.1
Sixth embodiment
N _W <3.9, N _M <4.5, N _T <6.5.

Therefore, as can be seen from the comparison above, whether arguably the zoom lens of this embodiment has a larger zoom ratio than that that in the embodiment of Japanese Patent Application Laid-Open No. 5-142475, the values of the number N of subdivisions decreased in reverse.

Also, as described above, in the sixth embodiment, since the rate of change of the conversion coefficient γ _{a assigned} to the direction of rotation is smaller than that in the conventional system, the values of the numbers N of the divisions become small. For this reason, the number of data of the conversion coefficient γ _a and the correction coefficient µ can be reduced and the storage capacity can be reduced.

Tables 60, 61 and 62 summarize the calculation results of the conversion coefficient K _a and the correction coefficient μ at the wide-angle end position (F = 28.8), the middle position (F = 50.0) and the telephoto end position (F = 103.0) according to the sixth embodiment. The arrangements of the tables and symbols are the same as those of the first embodiment. The position of the focusing lens in the first pair in the top two tables in each of tables 60, 61 and 62, ie in the third and fourth columns, is (R, ANGLE) = (0.0, 0.0), and indicates that this position corresponds to the infinitely corresponding position. Similarly, the position of the focusing lens in the fourth pair in the lower two tables in each of tables 60, 61 and 62, ie in the ninth and tenth columns, (R, ANGLE) = (0.5, -8.0), and it indicates that this position corresponds to the closest position in focus (R = 0.5 m) corresponding position.

Table 60

Conversion coefficient K _a : (rs), γ _a : (r) assigned to the direction of rotation, and correction coefficient µ: (l) at the wide-angle end position (28.8 mm) of the sixth embodiment

f = 28.8 mm

Table 61

Conversion coefficient K _a : (rs), γ _a : (r) assigned to the direction of rotation, and correction coefficient µ: (l) at the center position (50.0 mm) of the sixth embodiment

f = 50.0 mm

Table 62

Conversion coefficient K _a : (rs), γ _a : (r) assigned the direction of rotation and correction coefficient µ: (l) at the telephoto end position (103.0 mm) of the sixth embodiment

f = 103.0 mm

The calculation results of the change rate K _a with respect to γ _a at the infinite, in-focus arrangement and the closest, in-focus arrangement at the wide-angle end position of the center position and the telephoto end position in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 and in the sixth embodiment of the present invention are as follows.

Embodiment of Japanese Patent Application Laid-Open No. 5-142475

Sixth embodiment

Also, as described above, in the sixth embodiment, since the rate of change of K _{a in} γ _{a is} small compared to the conventional system, the contribution of the correction term (ΔBf / µ) in K _a = γ _a (1 - ΔBf / µ) continues to be reduced. For this reason, an error of the conversion coefficient K _a calculated based on γ _a and µ, or an error from the actual lens driving amount Δa obtained when only a pair of a conversion coefficient value γ _a and a correction coefficient value µ are set, be reduced.

Next, in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 and the sixth embodiment of the present invention, the lens driving amounts by focusing from an infinite, focusable lens array to the closest object distance and by focusing from the closest, focus lens array to the infinite object distance from the wide-angle end position, the center position and the telephoto end position is calculated from Δa = ΔBf / γ _a (1 - ΔBf / µ), and errors from the actual lens drive amounts are then calculated, the following values being obtained. It should be noted that the value of the correction coefficient µ while focusing from the infinite lens arrangement in focus to the closest object distance takes a value at the object distance (POS-5) and the value of the correction coefficient µ while focusing from the closest, im Focus lens arrangement to the infinite object distance takes a value at the object distance (POS-4).

Embodiment of Japanese Patent Application Laid-Open No. 5-142475

Sixth embodiment

Also, as described above, in the sixth embodiment, even if only a pair of a conversion coefficient value γ _a and a correction coefficient value µ are set for a given lens arrangement range, an error between the conversion coefficient K _a which is made up of γ _a and µ and that Linsenan drive amount Δa is calculated for focusing, small compared to the conventional system, and focusing can be realized with higher accuracy.

Table 63 summarizes the amount (ANGLE DA) of a rotation for focusing under one manual focusing using the focus cam (the middle table in Table 55) of the sixth embodiment, the amount X (mm) of a movement, and in the direction of the optical axis of the focusing lens unit according to the amount of rotation for focusing, and the shift amount Bf (mm) of the imaging point when the amount (DX) of movement in the direction of the optical axis is given together.  

It should be noted that the arrangement of the table and the reference symbols are the same like those in the first embodiment. The upper table in Table 63 summarizes the shift amount Bf of an imaging point corresponding to the photograph stands (R = 5.0, 3.0, 2.0, 1.5, 1.0, 0.7 and 0.5 m) in the respective zooming states those of the focus lengths (F = 28.8, 35.0, 50.0, 70.0, 85.0 and 103.0 mm) together and the middle table summarizes the values of the amount (ANGLE DA) of a rotation to the focus together to achieve an optimal focus that is in focus stands with regard to the respective photography distances are required. The lower ta belle summarizes the amounts (DX) of a movement in the direction of the optical axis, the respective lens units according to the amount (ANGLE DA) of a rotation Focusing in association with the respective focus lengths and photographing distances together.

Table 63

Shift amount Bf (mm) of an imaging point and amount (DX) (mm) of a movement for focusing in the sixth embodiment

As can be seen from Table 63, according to the zoom lens of the sixth embodiment, a so-called manual focus can be obtained because the shift amounts of the imaging point at the respective focus countries and photography distances are very small and they fall within the depth of the fo kus regardless of the zooming state and the photographing distance.

Seventh Embodiment

The seventh embodiment is directed to a zoom lens which has an arrangement with five units, ie a positive, a negative, a positive, a negative and a positive lens unit, and a focusing by a negative, second lens unit. In this zoom lens, the rotation amount ratio (a _F / a _Z ) of the rotation amount for focusing from the infinite position in focus to the closest position in focus (R = 0.5 m) becomes the amount of rotation Zoom from the wide-angle end position (F = 28.8) to the telephoto end position (F = 102.0) set so that it is -0.72.

Table 64 below summarizes various paraxial data of an optical system and Data for determining the shape of a focus cam according to the seventh embodiment shape together.

The upper table in Table 64 summarizes the focus lengths and the symmetry point interval data of the respective lens units of the optical system corresponding to the seventh Embodiment in association with six zooming states (focus lengths F = 28.8, 35.0, 50.0, 70.0, 85.0 and 102.0 mm) together.  

The middle table in Table 64 summarizes the wedge scan data when the shape of a focus cam in the second lens unit of the seventh embodiment a wedge function is expressed that corresponds to the angle of rotation of a rotatable Ob jective drum and the amount x of movement in the direction of the optical axis assigned.

Furthermore, the table below in Table 64 summarizes the infinite positions in focus (positions corresponding to infinity) at the respective focus lengths (F = 28.8, 35.0, 50.0, 70.0, 85.0 and 102.0 mm) and the amounts of a rotation (amounts of one Rotation for focusing) focusing on respective photographing distances (R = 5.0, 3.0, 2.0, 1.0, 0.7 and 0.5 m) using the focus cam of the seventh embodiment together. In the lower table in Table 64, since the amount of rotation for zooming from the wide-angle end position (F = 28.8) to the telephoto end position (F = 102.0) is set to be 10.0, and the amount of rotation for focusing from the infinite focus position to the closest focus position (R = 0.5 m) is set to be -7.2, the rotation amount ratio (a _F / a _Z ) of the rotation amount to focus on Amount of rotation for zooming in the sixth embodiment -0.72.

Table 64

Seventh embodiment f = 28.8 to 102.0 (rotation amount ratio: a _F / a _Z = -0.72)

Focus lengths and symmetry point intervals of lens units of the seventh embodiment

Focus cam shape (wedge interpolation sampling point) according to the seventh embodiment

Amount of rotation for zooming and amount of rotation for focusing in the seventh embodiment

(Rotation ratio: a _F / a _Z = -0.72)

Table 65 below summarizes the numerical data values of the cams in the focus lens unit in the seventh embodiment, this data by interpolation based on a wedge function based on the scan data of the Focus cams are calculated, which are summarized in the middle table in Table 64 are summarized. It should be noted that the meanings of the respective symbols in Ta belle 65 are the same as those according to the first embodiment.

Table 65

Numerical cam data values of a focusing lens unit in the seventh embodiment

The left table in Table 65 summarizes the numerical data values of the focus cam the seventh embodiment together and the right table in Table 65 summarizes the numerical data values of the zoom compensation cam of this embodiment together. A value obtained by synthesizing the amounts (2) of a movement in the Direction of the optical axis in the numerical data values of the focus cam and the zoom compensation cam in the range of the amount of rotation (ANGLE = 0.0) on the amount of a rotation (ANGLE = 10.0) is correct the movement point of the second lens unit, which using the Pa raxial data is calculated in the upper table in Table 64.

Tables 66, 67 and 68 below summarize the amount DX (mm) of a movement for focusing in the direction of the optical axis of the focusing lens unit, the magnification β _{x of} the respective lens units, the conversion coefficient γ _x , that of the direction of the optical axis is assigned, the slope (dx / da) of the focus cam and the conversion coefficient γ _a , which is assigned to the direction of a rotation at the wide-angle end position (F = 28.8), the middle position (F = 50.0) and the telephoto end position (F = 102.0) is together according to the seventh embodiment. The arrangements of the respective tables and the meanings of the reference symbols are the same as those of the first embodiment.

Table 66

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the wide-angle end position (28.8 mm) in the seventh embodiment

Image magnification β _{K of} the lens units at the wide-angle end position (28.8 mm) in the seventh embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the wide-angle end position (28.8 mm) in the seventh embodiment

Slope dx / da of the focus cam at the wide-angle end position (28.8 mm) in the seventh embodiment

Conversion coefficient γ _{a assigned} to the direction of rotation at the wide-angle end position (28.8 mm) in the seventh embodiment

Table 67

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the center position (50.0 mm) in the seventh embodiment

Magnification β _{K of} the lens units at the center position (50.0 mm) in the seventh embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the center position (50.0 mm) in the seventh embodiment

Slope dx / da of the focus cam at the central position (50.0 mm) in the seventh embodiment

Conversion coefficient γ _a , which is assigned to the direction of rotation at the center position (50.0 mm) in the seventh embodiment

Table 68

Amount DX (mm) of a movement to focus in the direction of the optical axis at the telephoto end position (102.0 mm) in the seventh embodiment

Image magnification β _{K of} the lens units at the telephoto end position (102.0 mm) in the seventh embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the telephoto end position (102.0 mm) in the seventh embodiment

Slope dx / da of the focus cam at the telephoto end position (102.0 mm) in the seventh embodiment

Conversion coefficient γ _a , which is assigned to the direction of rotation at the telephoto end position (102.0 mm) in the seventh embodiment

As can be seen from Tables 66, 67 and 68, the conversion coefficient γ _x , which is assigned to the direction of the optical axis, increases for each focus length, but the slope (dx / da) of the focus cam decreases if the photo distance comes closer to the closest distance. Therefore, as can be seen from these tables, the conversion coefficient γ _a , which is assigned to the direction of a rotation and which is defined as the product of the conversion coefficient γ _x and the slope (dx / da) of the focus cam, decreases when the photographer comes closer to the closest distance due to the influence of the slope (dx / da) of the focus cam. From Tables 66, 67 and 68, the rate of change from the infinite focus position to the closest focus position of the conversion coefficient γ _{a associated} with the direction of rotation is x0.55 at the wide-angle end position (F = 28.8), x0.48 at the middle position (F = 50.0) and x0.31 at the telephoto end position (F = 102.0). When the number N of divisions of the focus area is calculated with a change in the conversion coefficient γ _a in the seventh embodiment using the formula (a) and with that in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 is compared, the numbers N _W , N _M and N _{T of} the divisions at the wide-angle end position at the middle position and the telephoto end position each have the following values:
Embodiment of Japanese Patent Application Laid-Open No. 5-142475
N _W <9.3, N _M <10.1, N _T <8.1,
Seventh embodiment
N _W <3.2, N _M <4.0, N _T <6.3.

Therefore, although the zoom lens of this embodiment becomes larger Zoom ratio than that in the embodiment of the Japanese disclosed Patent application No. 5-142475 has the values of the numbers N of divisions conversely lowered.

Also, as described above, in the seventh embodiment, since the rate of change of the conversion coefficient γ _{a assigned} to the direction of rotation is smaller than that in the conventional system, the values of the numbers N of the divisions become small. For this reason, the number of data of the conversion coefficient γ _a and the correction coefficient µ can be reduced and the storage capacity can be reduced.

Tables 69, 70 and 71 summarize the calculation results of the conversion coefficient K _a and the correction coefficient µ at the wide-angle end position (F = 28.8), the middle position (F = 50.0) and the telephoto end position (F = 102.0) according to the seventh embodiment. The arrangements of the tables and symbols are the same as those of the first embodiment. The position of the focusing lens in the first pair in the top two tables, in each of tables 69, 70 and 71, ie in the third and fourth columns, is (R, ANGLE) = (0.0, 0.0), and indicates that this position corresponds to the infinitely corresponding position. Similarly, the position of the focusing lens in the fourth pair in the lower two tables in each of Tables 69, 70 and 71, ie in the ninth and 10th columns, (R, ANGLE) = (0.5, -7.2), and it indicates that this position corresponds to the closest position in focus (R = 0.50 m) corresponding position.

Table 69

Conversion coefficient K _a : (rs), γ _a : (r) assigned to the direction of rotation, and correction coefficient µ: (l) at the wide-angle end position (28.8 mm) of the seventh embodiment

f = 28.8 mm

Table 70

Conversion coefficient K _a : (rs), γ _a (r) assigned to the direction of rotation, and correction coefficient µ: (l) at the center position (50.0 mm) of the seventh embodiment

f = 50.0 mm

Table 71

Conversion coefficient K _a : (rs), γ _a : (r) assigned the direction of rotation and correction coefficient µ: (l) at the telephoto end position (102.0 mm) of the seventh embodiment

f = 102.0 mm

The calculation results of the rate of change of K _a with respect to γ _a at the infinite arrangement in focus and the closest one. arrangement in focus at the wide-angle end position, the middle position and the telephoto end position in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 and in the seventh embodiment of the present invention are as follows.

Embodiment of Japanese Patent Application Laid-Open No. 5-142475

Seventh version

Also, as described above, in the seventh embodiment, since the rate of change of K _{a in} γ _{a is} small compared to the conventional system, the contribution of the correction term (ΔBf / µ) in K _a = γ _a (1 - ΔBf / µ) continues to be reduced. For this reason, an error of the conversion coefficient K _a calculated based on γ _a and µ or an error from the actual lens driving amount Δa obtained when only a pair of a conversion coefficient value γ _a and a correction coefficient value µ are set become.

Next, in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 and the seventh embodiment of the present invention, the lens drive amounts focusing from an infinite focus lens arrangement to the closest object distance and focusing from the closest focus lens arrangement to the infinite object distance at the wide-angle end position that The center position and the telephoto end position are calculated from Δa = ΔBf / γ _a (1 - ΔBf / µ), and errors from the actual lens drives are then calculated, the following values being obtained. It should be noted that the value of the correction coefficient µ while focusing from the infinite lens arrangement in focus to the closest object distance takes a value at the object distance (POS-5) and the value of the correction coefficient µ while focusing from the closest, lens arrangement in focus to the infinite object distance assumes a value at the object distance (POS-4).

Embodiment of Japanese Patent Application Laid-Open No. 5-142475

Seventh embodiment

Also, as described above, in the seventh embodiment, even if only a pair of a conversion coefficient value γ _a and a correction coefficient value µ are set for a given lens arrangement range, an error between the conversion coefficient K _a which is made up of γ _a and µ and that Linsenan drive amount Δa is calculated for focusing, small compared to the conventional system, and focusing can be realized with higher accuracy.

Table 72 summarizes the amount (ANGLE DA) of a rotation for focusing under one manual focusing using the focus cam (the middle table in Table 64) of the seventh embodiment, the amount X (mm) of a movement, and in the direction of the optical axis of the focusing lens unit according to the amount of rotation for focusing, and the shift amount Bf (mm) of the imaging point when the amount (DX) of movement in the direction of the optical axis is given together.

It should be noted that the arrangement of the table and the reference symbols are the same like those in the first embodiment. The upper table in Table 72 summarizes the shift amount Bf of an imaging point according to the photographers distances (R = 5.0, 3.0, 2.0, 1.5, 1.0, 0.7 and 0.5 m) in the respective zooming Zu the focus lengths (F = 28.8, 35.0, 50.0, 70.0, 85.0 and 102.0 mm) together and the middle table summarizes the values of the amount (ANGLE DA) of a rotation to Fo kissing together, to achieve an optimal, in focus State with regard to the respective photography distances are required. The lower one Table summarizes the amounts (DX) of a movement in the direction of the optical axis, of the respective lens units according to the amount (ANGLE DA) of a rotation for focusing in association with the respective focus lengths and photographing distances that together.

Table 72

Displacement amount Bf (mm) of an imaging point and amount (DX) (mm) of a movement for focusing in the seventh embodiment

As can be seen from table 72, according to the zoom lens the seventh embodiment, a so-called manual focusing can be obtained since the amounts of displacement of the imaging point at the respective focus lengths and Photography distances are very small and they do not fall within the depth of focus depending on the zooming state and the photographing distance.

Eighth Embodiment

The eighth embodiment is directed to a zoom lens which has an arrangement with four units, ie a positive, a negative, a positive and a negative lens unit, and achieves focusing by means of a positive, third lens unit. In this zoom lens, the rotation amount ratio (a _F / a _Z ) of the rotation amount for focusing from the infinite position in focus to the closest position in focus (R = 1.2 m) becomes the amount of rotation Zoom from the wide-angle end position (F = 72.0) to the telephoto end position (F = 200.0) set to be -0.75.

Table 73 below summarizes various paraxial data of an optical system and Data for defining the shape of a focus cam according to the eighth embodiment shape together.

The upper table in Table 73 summarizes the focus lengths and the symmetry point interval data of the respective lens units of the optical system according to the eighth  Embodiment in association with six zooming states (focus lengths F = 72.0, 105.0, 135.0,150.0 and 200.0 mm) together.

The middle table in Table 73 summarizes the wedge scan data when the shape of a focus cam in the second lens unit of the eighth embodiment a wedge function is expressed that corresponds to the angle of rotation of a rotatable Ob jective drum and the amount x of movement in the direction of the optical axis assigned.

Furthermore, the lower table in Table 73 summarizes the infinite positions in focus (positions corresponding to infinity) at the respective focus lengths (F = 72.0, 105.0, 135.0, 150.0 and 200.0 mm) and the amounts of a rotation (amounts of one rotation Focusing) focusing on respective photographing distances (R = 5.0, 4.0, 3.0, 2.0, 1.5 and 1.2 m) using the focus cam of the eighth embodiment together. In the lower table in Table 73, since the amount of rotation for zooming from the wide-angle end position (F = 72.0) to the telephoto end position (F = 200.0) is set to be 10.0, and the amount of rotation for focusing from the infinite focus position to the closest focus position (R = 1.2 m) is set to be -7.5, the rotation amount ratio (a _F / a _Z ) of the rotation amount to focus on Amount of rotation for zooming in the eighth embodiment -0.75.

Table 73

Eighth embodiment f = 72.0 to 200.0 (rotation amount ratio: a _F / a _Z = -0.75)

Focus lengths and symmetry point intervals of lens units of the eighth embodiment

Focus cam shape (wedge interpolation sampling point) according to the eighth embodiment

Amount of a rotation for zooming and amount of a rotation for focusing the eighth embodiment

(Rotation amount ratio: a _F / a _Z = -0.75)

Table 74 below summarizes the numerical data values of the cams in the focus end lens unit in the eighth embodiment, this data by interpolation based on a wedge function based on the scan data of the Focus cams are calculated, which are summarized in the middle table in Table 73 are summarized. It should be noted that the meanings of the respective symbols in Ta belle 74 are the same as those according to the first embodiment.

Table 74

Numerical cam data values of a focusing lens unit in the eighth embodiment

The left table in Table 74 summarizes the numerical data values of the focus cam the eighth embodiment together and the right table in Table 74 summarizes the numerical data values of the zoom compensation cam of this embodiment together. A value obtained by synthesizing the amounts (3) of a movement in the Direction of the optical axis in the numerical data values of the focus cam and the zoom compensation cam in the range of the amount of rotation (ANGLE = 0.0) on the amount of a rotation (ANGLE = 10.0) is correct the movement point of the third lens unit, which using the Para xial data is calculated in the upper table in Table 73.

Tables 75, 76 and 77 below summarize the amount DX (mm) of a movement for focusing in the direction of the optical axis of the focusing lens unit, the magnification β _{x of} the respective lens units, the conversion coefficient γ _x , the direction of the optical axis assigned, the slope (dx / da) of the focus cam and the conversion coefficient γ _a , which is assigned to the direction of a rotation at the wide-angle end position (F = 72.0), the middle position (F = 135.0) and the telephoto end position (F = 200.0) is, according to the eighth embodiment, each together. The arrangements of the respective tables and the meanings of the symbols are the same as those of the first embodiment.

Table 75

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the wide-angle end position (72.0 mm) in the eighth embodiment

Magnification β _{K of} the lens units at the wide-angle end position (72.0 mm) in the eighth embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the wide-angle end position (72.0 mm) in the eighth embodiment

Slope dx / da of the focus cam at the wide-angle end position (72.0 mm) in the eighth embodiment

Conversion coefficient γ _a , which is assigned to the direction of rotation at the wide-angle end position (72.0 mm) in the eighth embodiment

Table 76

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the center position (135.0 mm) in the eighth embodiment

Magnification β _{K of} the lens units at the central position (135.0 mm) in the eighth embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the central position (135.0 mm) in the eighth embodiment

Slope dx / da of the focus cam at the middle position (135.0 mm) in the eighth embodiment

Conversion coefficient γ _a , which is assigned to the direction of rotation at the center position (135.0 mm) in the eighth embodiment

Table 77

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the telephoto end position (200.0 mm) in the eighth embodiment

Magnification β _{K of} the lens units at the telephoto end position (200.0 mm) in the eighth embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the telephoto end position (200.0 mm) in the eighth embodiment

Slope dx / da of the focus cam at the telephoto end position (200.0 mm; in the eighth embodiment

Conversion coefficient γ _a , which is assigned to the direction of rotation at the telephoto end position (200.0 mm) in the eighth embodiment

As can be seen from Tables 75, 76 and 77, the conversion coefficient γ _{x associated with} the direction of the optical axis undergoes almost no change in the wide-angle end position and the center position, but it increases in the telephoto end position when the photographing distance gets closer to the closest distance, and the slope (dx / da) of the focus cam decreases when the photographing distance gets closer to the closest distance at the respective focus lengths. Therefore, as can be seen from these tables, the conversion coefficient γ _{a associated with} the direction of rotation, which is defined as the product of the conversion coefficient γ _x and the slope (dx / da) of the focus cam, decreases when the photographing distance comes closer to the closest distance due to the influence of the slope (dx / da) of the focus cam. Tables 75, 76 and 77 show the rate of change from the infinite, in-focus position to the closest, in-focus position of the conversion coefficient γ _a , which is associated with the direction of rotation, x0.42 at the wide-angle end position ( F = 72.0), x0.41 at the middle position (F = 135.0) and x0.39 at the telephoto end position (F = 200.0). When the number N of divisions of the focus area is changed under a change in the conversion coefficient γ _a in the eighth embodiment using the formula (a) and with that in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 is compared, the numbers N _W , N _M and N _{T of} the subdivisions at the wide-angle end position, the middle position and the telephoto end position each have the following values:

Embodiment of Japanese Patent Application Laid-Open No. 5-142475
N _W <9.3, N _M <10.1, N _T <8.1
Eighth embodiment
N _W <4.8, N _M <4.9, N _T <5.1.

Also, as described above, in the eighth embodiment, since the rate of change of the conversion coefficient γ _{a assigned} to the direction of rotation is smaller than that in the conventional system, the values of the numbers N of the divisions become small. For this reason, the number of data of the conversion coefficient γ _a and the correction coefficient µ can be reduced and the storage capacity can be reduced.

Tables 78, 79 and 80 summarize the calculation results of the conversion coefficient K _a and the correction coefficient µ at the wide-angle end position (F = 72.0), the middle position (F = 135.0) and the telephoto end position (F = 200.0) according to the eighth embodiment. The arrangements of the tables and reference symbols are the same as those of the first embodiment. The position of the focusing lens in the first pair in the top two tables, in each of tables 78, 79 and 80, ie in the third and fourth columns, is (R, ANGLE) = (0.0, 0.0) and indicates that this position corresponds to the infinitely corresponding position. Similarly, the position of the focusing lens in the fourth pair in the lower two tables in that of tables 78, 79 and 80, ie in the ninth and 10th columns 99999 00070 552 001000280000000200012000285919988800040 0002019530770 00004 99880te, (R, ANGLE) = (1.2, -7.5), and it indicates that this position corresponds to the position closest to the one in focus (R = 1.2 m).

Table 78

Conversion coefficient K _a : (rs), γ _a : (r) assigned to the direction of rotation, and correction coefficient µ: (l) at the wide-angle end position (72.0 mm) of the eighth embodiment

f = 72.0 mm

Table 79

Conversion coefficient K _a : (rs), γ _a : (r) assigned to the direction of rotation, and correction coefficient µ: (l) at the middle position (135.0 mm) of the eighth embodiment

f = 135.0 mm

Table 80

Conversion coefficient K _a : (rs), γ _a : (r) assigned to the direction of rotation and correction coefficient µ: (l) at the telephoto end position (200.0 mm) of the eighth embodiment

f = 200.0 mm

The calculation results of the rate of change of K _a with respect to γ _a at the infinite arrangement in focus and the closest one. arrangement in focus at the wide-angle end position, the middle position and the telephoto end position in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 and in the eighth embodiment of the present invention are as follows.

Embodiment of Japanese Patent Application Laid-Open No. 5-142475

Eighth embodiment

Also, as described above, in the eighth embodiment, since the rate of change of K _{a in} γ _{a is} small compared to the conventional system, the contribution of the correction term (ΔBf / µ) in K _a = γ _a (1 - ΔBf / µ) continues to be reduced. For this reason, an error of the conversion coefficient K _a calculated based on γ _a and µ, or an error from the actual lens driving amount Δa obtained when only a pair of a conversion coefficient value γ _a and a correction coefficient value µ are set becomes.

Next, in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 and the eighth embodiment of the present invention, the lens drive amounts focusing from an infinite focus lens arrangement to the closest object distance and focusing from the closest focus lens arrangement to the infinite object distance at the wide-angle end position, the center position and the telephoto end position is calculated from Δa = ΔBf / γ _a (1 - ΔBf / µ), and errors from the actual lens drive slides are then calculated, the following values being obtained. It should be noted that the value of the correction coefficient µ while focusing from the infinite lens arrangement in focus to the closest object distance takes a value at the object distance (POS-5) and the value of the correction coefficient µ while focusing from the closest, im Focus lens arrangement to the infinite object distance takes a value at the object distance (POS-4).

Embodiment of Japanese Patent Application Laid-Open No. 5-142475

Eighth embodiment

Also, as described above, in the eighth embodiment, even if only a pair of a conversion coefficient value γ _a and a correction coefficient value µ are set for a given lens arrangement range, an error between the conversion coefficient K _a which is made up of γ _a and µ and that Lens drive amount Δa is calculated for focusing, small compared to the conventional system, and focusing can be realized with higher accuracy.

Table 81 summarizes the amount (ANGLE DA) of a rotation for focusing under one manual focusing using the focus cam (the middle table in Table 73) of the eighth embodiment, the amount X (mm) of a movement, namely in the direction of the optical axis of the focusing lens unit accordingly the amount of rotation for focusing, and the shift amount Bf (mm) of Imaging point when the amount (DX) of movement in the direction of the optical Axis is given together.

It should be noted that the arrangement of the table and the reference symbols are the same like those in the first embodiment. The upper table in Table 81 summarizes the shift amount Bf of an imaging point according to the photographers distances (R = 5.0, 4.0, 2.0, 1.5 and 1.2 m) in the respective zooming states of the Focus lengths (F = 72.0, 105.0, 135.0, 150.0 and 200.0 mm) together and the middle one The table summarizes the values of the amount (ANGLE DA) of a rotation for focusing together to achieve an optimal, in-focus state of the respective photographing distances is required. The table below summarizes the Amounts (DX) of a movement in the direction of the optical axis, the respective Lin units corresponding to the amount (ANGLE DA) of a rotation for focusing in Allocation to the respective focus lengths and photographing distances together.

Table 81

Shift amount Bf (mm) of an imaging point and amount (DX) (mm) of a movement for focusing in the eighth embodiment

As can be seen from Table 81, according to the zoom lens the eighth embodiment, a so-called manual focusing can be obtained, since the amounts of displacement of the imaging point at the respective focus lengths and Photography distances are very small and they do not fall within the depth of focus depending on the zooming state and the photographing distance.

In the eighth embodiment, according to Tables 75 and 76, the conversion coefficient γ _x , which is assigned to the direction of the optical axis, lowers slightly at the wide-angle end position and at the center position when the photographing distance comes closer to the closest distance. Therefore, since the conversion coefficient γ _{a associated with} the direction of rotation is defined as the product of the conversion coefficient γ _x and the slope (dx / da) of the focus cam, it can be considered to be the The slope (dx / da) of the focus cam preferably increases as the photographing distance comes closer to the closest distance, as in the embodiment of Japanese Patent Application Laid-Open No. 5-142475. However, since the conversion coefficient γ _{x associated with} the direction of the optical axis greatly increases at the telephoto end position compared to the wide-angle end position and the center position, the slope (dx / da) of the focus cam preferably decreases when the photographing distance came closer to the closest distance, similar to the present invention, taking into account the rate of change of the conversion coefficient γ _a , which is assigned to the direction of rotation as a whole.

Ninth Embodiment

A zoom lens of the ninth embodiment is a zoom lens which has a four-unit arrangement, that is, a positive, a negative, a positive and a positive lens unit, and achieves focusing by a negative second lens unit as in the embodiment Japanese Patent Application Laid-Open No. 5-142475 which is previously described in detail as prior art. In this zoom lens, the rotation amount ratio (a _F / a _Z ) of the rotation amount for focusing is changed from the infinite position in focus to the closest position in focus (R = 0.85 m) to the amount of rotation Zoo men from the wide-angle end position (F = 36.0) to the telephoto end position (F = 103.0) set so that it is -0.75.

Table 82 below summarizes various paraxial data of an optical system and Data for defining the shape of a focus cam according to the ninth embodiment shape together.

The upper table in Table 82 summarizes the focus lengths and the symmetry point interval data of the respective lens units of the optical system according to the ninth Embodiment together.

In this table, F1, F2, F3 and F4 are the focus lengths of the first, second, third and fourth lens units, and D1, D2, D3 and D4 are the symmetry, respectively point interval between the first and the second lens unit, the symmetry point Interval between the second and third lens units, the symmetry point inter vall between the third and fourth lens units and the symmetry point interval between the fourth lens unit and a predetermined imaging plane in six zooming states (F = 36.0, 50.0, 60.0, 70.0, 85.0 and 103.0 mm). That is why this data is the same as the various paraxial data (upper table in Table 1) the embodiment of Japanese Patent Application Laid-Open No. 142475.

The middle table in Table 82 summarizes the wedge scan data when the shape (a curve g _2F in Fig. 3B) of the focus cam in the second lens unit of the ninth embodiment used for focusing is expressed by the above-mentioned wedge function associated with the angle of rotation of a rotatable lens barrel and the amount x of movement in the direction of the optical axis.

Furthermore, the lower table in Table 82 summarizes the infinite positions in focus (positions corresponding to infinity) at the respective focus lengths (F = 36.0, 50.0, 60.0, 70.0, 85.0 and 103.0 mm) and the amounts of a rotation (amounts of a rotation for focusing) while focusing on respective photographing distances (R = 5.0, 3.0, 2.0, 1.5, 1.0 and 0.85 m) using the focus cam of the ninth embodiment together. In the lower table in Table 82, since the amount of rotation for zooming from the wide-angle end position (F = 36.0) to the telephoto end position (F = 103.0) is set to be 10.0, and the amount of rotation for focusing is the infinite position in focus to the closest position in focus (R = 0.85 m) is set to be -7.5, the rotation amount ratio (a _F / a _Z ) of the rotation amount for focusing to Amount of rotation for zooming in the ninth embodiment -0.75.

Table 82

Ninth embodiment f = 36.0 to 103.0 (rotation amount ratio: a _F / a _Z = -0.75)

Focus lengths and symmetry point intervals of lens units of the ninth embodiment

Focus cam shape (wedge interpolation sampling point) according to the ninth embodiment

Amount of rotation for zooming and amount of rotation for focusing of the ninth embodiment

(Rotation amount ratio: a _F / a _Z = -0.75)

Table 83 below summarizes the numerical data values of the cams in the  focusing lens unit together in the eighth embodiment, this Data by interpolation based on a wedge function based on the sample data of the focus cam are calculated, which are summarized in the middle table in Table 82 are quantified. In this table, (ANGLE) is the angle of rotation of the rotatable one Lens drum, (2) is the amount (mm) of movement in the direction of the optical The axis of the second lens unit and (F) is the focus length (mm) of the entire sy stems in an infinite state in focus according to the Be ANGLE of a rotation.

Table 83

Numerical cam data values of a focusing lens unit in the ninth embodiment

The left table in Table 83 summarizes the numerical data values of the focus cam of the ninth embodiment, and the right table in Table 83 summarizes the numerical data values of the zoom compensation cam of this embodiment. A value obtained by synthesizing the amounts (2) of movement in the direction of the optical axis in the numerical data values of the focus cam and the zoom compensation cam in the range from the amount of rotation (ANGLE = 0.0) to the amount of rotation (ANGLE = 10.0) is obtained, coincides with the movement point (a curve g₂ in Fig. 3A) of the second lens unit, which is calculated using the paraxial data in the upper table in Table 82.

Therefore, the zoom compensation cam (a curve g _2H in FIG. 3B) is determined by subtracting the focus cam (the curve g _2F in FIG. 3B) from the movement point (curve g₂ in FIG. 3A) while zooming the second lens unit , which is determined by the paraxial data in the upper table in Table 82.

FIGS. 3A and 3B and Fig. 4 will be described briefly below.

Fig. 3A shows the paraxial arrangement and the moving positions while zooming the zoom lens according to the ninth embodiment, and Fig. 3B shows the shapes of the focus cam and the zoom compensation cam of the second lens unit of this embodiment. Like Figs. 3A and 3B show, G1, G2, G3 and G4 each represent the first, second, third and fourth lens unit, and g₁, g₂, g₃ and g₄ each represent the movement points while zooming the first, second, third and fourth lens unit. In addition, g _2F and g _2H each represent the shapes of the focus cam and the zoom compensation cam of the second lens unit. As described above, there is a shape that is obtained by synthesizing the focus cam g _2F and the zoom compensation cam g _{2H of} the second lens unit is obtained, with the movement point g₂ of the second lens unit.

Fig. 4 is a view for explaining the shape of the focus cam g _2F the ninth embodiment. As shown in FIG. 4, (f = 36; R = un) and (f = 36; R = 0.85) each place the positions in focus at the infinite and the closest distance (R = 0.85 m) at the Wide-angle end position and coordinate positions (x; a) on the focus cam are (x; a) = (0; 0) and (x; a) = (1,037; -7.5). On the other hand, (f = 103; R = un) and (f 103; R = 0.85) each represent the positions in focus at the infinite and the closest distance (R = 0.85 m) at the telephoto end position, and coordinate positions ( x; a) on the focus cam are (x; a) = (-4654; 10) and (x; a) = (-0.574; 2.5).

While zooming from the wide-angle end position to the telephoto end position, the second lens unit on the focus cam g _2F moves from the coordinate position (0; 0) to the coordinate position (-4.654; 10) for an infinite object and from the coordinate position (1.037; - 7.5) to the coordinate position (-0.574; 2.5) for a closest object distance. Therefore, the second lens unit 10.0 moves in the direction of rotation (the direction of an axis a) in both cases. On the other hand, while focusing from the infinite arrangement to the closest object distance, the second lens unit on the focus cam g _2F moves from the coordinate position (0; 0) to the coordinate position (1,037; -7.5) at the wide-angle end position and from the coordinate position ( -4654; 10) to the coordinate position (-0.574; 2.5) at the telephoto end position. Therefore, the second lens unit moves -7.5 in the direction of rotation (the direction of the axis a) at these ends. In contrast, in the direction of the optical axis (the direction of an axis x), the second lens unit moves by 1,037 at the wide-angle end position and by 4.08 at the telephoto end position.

Since the shape of the focus cam g _{2F is} obtained by interpolating the coordinates (f = 36; R = 0.85), (f = 36; R = un), (f = 103; R = 0.85) and (f = 103; R = un) is determined by the wedge function, the change in the slope (dx / da) of the focus cam g _2F becomes larger since the absolute value of the x coordinate of (f = 36; R = 0.85) is smaller or there the absolute value of the x coordinate of (f = 103; R = un) is larger. More specifically, since the ratio (Δx _TR / Δx _WR ) between the amounts Δx _TR and Δx _{WR of} the movement in the direction of the optical axis of the focusing lens unit, that for focusing from the infinite position to the closest distance position at the wide-angle end position or the telephoto end position is larger, the change in the slope (dx / da) of the focus cam is larger.

Tables 84, 85 and 86 below summarize the amount DX (mm) of a movement for focusing in the direction of the optical axis of the focusing lens unit, the magnification β _{x of} the respective lens units, the conversion coefficient γ _x , that of the direction of the optical axis is assigned, the slope (dx / da) of the focus cam and the conversion coefficient γ _a , which is assigned to the direction of a rotation at the wide-angle end position (F = 36.0), the middle position (F = 50.0) and the telephoto end position (F = 103.0) is together according to the ninth embodiment. In these tables, (R) on the left is the photographing distance (m), (ANG) is the rotation amount on the focus cam focusing on the respective photographing distances, and 1), 2), 3) and 4) on the right represent the first, the second, the third and the fourth lens unit. Also in these tables, the first table summarizes the amount DX (mm) of a movement for focusing in the direction of the optical axis while focusing on the respective photographing distances (R = 10.0, 5.0, 3.0, 2.0,1.5,1.0 and 0.85 m) (note that the movement towards the object side is positive) together. The second table summarizes the magnifications β _{K of} the respective lens units in a state in focus at the respective photographing distances (R = 10.0, 5.0, 3.0, 2.0,1.5,1.0 and 0.85 m). The third table summarizes the conversion coefficient γ _x , which is assigned to the direction of the optical axis of the focusing lens unit in a state in focus at the respective photographing distances (R = 10.0, 5.0, 3.0, 2.0, 1.0 and 0.85 m). Furthermore, the fourth table summarizes the slope (dx / da) of the focus cam at the positions on the focus cam corresponding to a state in focus at the respective photographing distances (R = 10.0, 5.0, 3.0, 2.0,1.5,1.0 and 0.85 m) together and the fifth table summarizes the conversion coefficient γ _a which corresponds to the direction of rotation of the focusing lens unit in a state in focus at the respective photographing distances (R = 10.0, 5.0, 3.0, 2.0, 1.5, 1.0 and 0.85 m) is assigned together.

Table 84

Amount DX (mm) of a movement to focus in the direction of the optical axis at the wide-angle end position (36.0 mm) in the ninth embodiment

Image magnification β _{K of} the lens units at the wide-angle end position (36.0 mm) in the ninth embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the wide-angle end position (36.0 mm) in the ninth embodiment

Slope dx / da of the focus cam at the wide-angle end position (36.0 mm) in the ninth embodiment

Conversion coefficient γ _{a assigned} to the direction of rotation at the wide-angle end position (36.0 mm) in the ninth embodiment

Table 85

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the center position (50.0 mm) in the ninth embodiment

Image magnification β _{K of} the lens units at the central position (50.0 mm) in the ninth embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the center position (50.0 mm) in the ninth embodiment

Slope dx / da of the focus cam at the central position (50.0 mm) in the ninth embodiment

Conversion coefficient γ _{a assigned} to the direction of rotation at the center position (50.0 mm) in the ninth embodiment

Table 86

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the telephoto end position (103.0 mm) in the ninth embodiment

Image magnification β _{K of} the lens units at the telephoto end position (103.0 mm) in the ninth embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the telephoto end position (103.0 mm) in the ninth embodiment

Slope dx / da of the focus cam at the telephoto end position (103.0 mm) in the ninth embodiment

Conversion coefficient γ _{a associated with} the direction of rotation at the telephoto end position (103.0 mm) in the ninth embodiment

As can be seen from Tables 84, 85 and 86, the conversion coefficient γ _x , which is assigned to the direction of the optical axis, increases at each focus length, but the slope (dx / da) of the focus cam decreases, if the photographing distance gets closer to the closest distance at the respective focus lengths. Therefore, as can be seen from these tables, the conversion coefficient γ _{a associated with} the direction of rotation that is defined as the product of the conversion coefficient γ _x and the slope (dx / da) of the focus cam decreases if the Photographing distance comes closer to the closest distance by the influence of the slope (dx / da) of the focus cam, in contrast to the embodiment of Japanese Patent Application Laid-Open No. 5-142475.

As described above, when the ratio (Δx _TR / Δx _WR ) between the amounts Δx _TR and Δx _WR of movement in the optical axis direction of the focusing lens unit, it becomes necessary to focus from the infinite position to the closest distance position is large at the wide-angle end position and the telephoto end position, the degree of decrease in the slope (dx / da) of the focus cam is also large. For this reason, the conversion coefficient γ _a , which is assigned to the direction of rotation, further decreases under the influence of the slope (dx / da) of the focus cam when the photographing distance comes closer to the closest distance.

From Tables 84, 85 and 86, the rate of change from the infinite position in focus to the closest position in focus of the conversion coefficient γ _{a associated} with the direction of rotation is x0.50 at the wide-angle end position (F = 36.0), x0.47 at the middle position (F = 50.0) and x0.34 at the telephoto end position (F = 103.0). When the number N of divisions of the focus area under a change in the conversion coefficient γ _a in the ninth embodiment is calculated using the formula (a) and with that in the embodiment of Japanese Patent Application Laid-Open No. 5-142475, the numbers N _W , N _M and N _{T of} the subdivisions at the wide-angle end position, the middle position and the telephoto end position each have the following values:
Embodiment of Japanese Patent Application Laid-Open No. 5-142475
N _W <9.3, N _M <10.1, N _T <8.1
Ninth embodiment
N _W <3.8, N _M <4.1, N _T <5.9.

Therefore, as from a comparison with the previously calculated values in the Embodiment of Japanese Patent Application Laid-Open No. 5-142475 he As can be seen, the values of the ninth embodiment are remarkably small.

As described above, in the zoom lens of the ninth embodiment, since the rate of change from the infinite focus position to the closest focus position of the conversion coefficient γ _{a associated with} the rotation direction can be much smaller than that in the embodiment of Japanese Patent Application Laid-Open No. 5-142475, the number of data of the conversion coefficient γ _a and the correction coefficient µ can be reduced, and the storage capacity can be reduced.

Tables 87, 88 and 89 summarize the calculation results of the conversion coefficient K _a and the correction coefficient µ at the wide-angle end position (F = 36.0), the middle position (F = 50.0) and the telephoto end position (F = 103.0) according to the ninth embodiment. In these tables, (R) is the object distance (m), (ANG) is the rotation amount for focusing from the infinitely corresponding position on the focus cam, (r) is the conversion coefficient γ _a in the rotation direction, (rs) is the conversion coefficient K₂, (bf) is the defocus amount (mm) and (l) is the correction coefficient µ. Each table has a matrix structure, and eight rows in the vertical direction indicated by (POS) represent the object positions (R = 10.0, 5.0, 3.0, 2.0, 1.5, 1.0 and 0.85 mm), and four pairs (R , ANGLE) in the horizontal direction represent the lens arrangements of the focusing lens unit.

More specifically, the position of the focusing lens in the first pair in the top two tables in each of tables 87, 88 and 89, that is, in the third and fourth columns (R, ANGLE) = (0.0, 0.0), and so on indicates that this position corresponds to the infinitely corresponding position. Therefore, the third column (r) in the first table represents the value of the conversion coefficient γ _a in the rotation direction when the focusing lens unit is focused on an infinite object, and the fourth column (rs) represents the value of the conversion coefficient K _a when the focusing lens unit is moved from a focus state on an infinite object to a focus state on an object distance in the second column. Furthermore, the third column (bf) in the second table represents the defocus amount ΔBf from a specific imaging position when the position of the focusing lens unit corresponds to the infinitely corresponding position and an object is arranged at an object distance in the second column, and that fourth column (l) represents the value of the correction coefficient μ when the focussing lens unit is moved from a state in focus on an infinite object to a state in focus on the object distance in the second column.

Similarly, the position of the focusing lens unit in the fourth pair is in the lower two tables in each of tables 87, 88 and 89, ie in the ninth and tenth columns. (R, ANGLE) = (0.85, -7.5), and it indicates that this position corresponds to the closest position in focus (R = 0.85 m) corresponding position. Therefore, the ninth column (r) in the third table represents the value of the conversion coefficient γ _a in the direction of rotation when the focusing lens unit is focused on a closest object distance (R = 0.85 m), and the 10th column (rs) represents the value of the conversion coefficient K _a when the focusing lens unit is moved from a state in focus to the closest object distance (R = 0.85 m) to a state in focus at an object distance in the second column. Furthermore, the ninth column (bf) in the fourth table represents the defocus amount ΔBf from a predetermined imaging position when the position of the focusing lens unit corresponds to the closest position and the object is located at an object distance in the second column, and the tenth column (l) represents the value of the correction coefficient µ when the focusing lens unit from a focus in the state at the closest object distance (R = 0.85 m) to a state in focus at the object distance in the second column is moved.

As described above, since the conversion coefficient in the rotation direction is calculated by K _a = ΔBf / (1 - K _a / γ _a ) (where Δa: the rotation amount for focusing), and the correction coefficient µ by µ = ΔBf / (1 - K _a / γ _a ) is calculated, the value of the conversion coefficient K _a (eighth row, fourth column in the first table: -0.233) when the focusing lens unit from a state in focus on the infinite object to a state in focus at the object distance (R = 0.85 m), calculated in Table 87 by K _a = 1.75 / -7.5 = -0.233 using ΔBf = 1.75 and Δa = -7.5. On the other hand, the value of the correction coefficient (eighth row, fourth column in the second table: 7.46) is calculated as µ = 7.46 using ΔBf = 1.75, K _a = -0.233 and γ _a = -0.304.

Table 87

Conversion coefficient K _a : (rs), γ _a : (r) assigned to the direction of rotation, and correction coefficient µ: (l) at the wide-angle end position (36.0 mm) of the ninth embodiment

f = 36.0 mm

Table 88

Conversion coefficient K _a : (rs), γ _a : (r) assigned to the direction of rotation, and correction coefficient µ: (l) at the center position (50.0 mm) of the ninth embodiment

f = 50.0 mm

Table 89

Conversion coefficient K _a : (rs), γ _a : (r) assigned the direction of rotation and correction coefficient µ: (l) at the telephoto end position (103.0 mm) of the ninth embodiment

f = 103.0 mm

As can be seen from Tables 87, 88 and 89 above, when there is a change in the conversion coefficient K _a : (rs) (e.g. the fourth column in the first table) on a given lens arrangement (e.g. due to the infinite arrangement in focus), the rate of change is small compared to the change in K _a (Tables 6, 7 and 8) in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 that was previously tested.

More specifically, when the fact that the conversion coefficient K _a in the rotation direction is defined by K _a = ΔBf / Δa and the defocus amount ΔBf is the same as that in the embodiment of Japanese Patent Application Laid-Open No. 5-142475, taking into account the same lens arrangement, the amount Δa of rotation for focusing in the ninth embodiment on the infinite object side is relatively smaller than that on the closest object side, compared with Japanese Patent Application Laid-Open No. 5-142475. In fact, when the ratio between the rotation amount for focusing under the closest distance (R = 0.85 m) and the rotation amount for focusing under the object distance (R = 5.0 m) is calculated from Tables 1 and 82, this 3,379 / 10.0 = 0.338 in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 while it becomes -0.9 / -7.5 = 0.120 in the ninth embodiment. As described above, when the focus cam is used with the arrangement of the present invention, since the amount Δa of rotation for focusing becomes relatively smaller on the infinite object side, the conversion coefficient K _a becomes relatively large on the infinite object side, and hence the change in the conversion coefficient K _a in the direction of rotation can be reduced compared to the conventional system.

The calculation results of the change rate of K _a with respect to γ _a at the infinite arrangement in focus and the closest arrangement in focus at the wide-angle end position (F = 36.0), the middle position (F = 50.0) and the telephoto end position (F = 103.0) in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 and in the ninth embodiment of the prior invention are as follows.

Embodiment of Japanese Patent Application Laid-Open No. 5-142475

Ninth embodiment

As described above, according to the present invention, since the rate of change of K _a with respect to γ _{a is} small compared to the conventional system, the contribution of the correction term (ΔBf / µ) to K _a = γ _a (1- ΔBf / µ) can be further reduced, the value of the correction coefficient µ can be set to be large compared to the defocus amount ΔBf, and at the same time the change in the correction coefficient µ can be decreased.

Therefore, even if only a pair of a conversion coefficient value γ _a and a correction coefficient value µ are set for a given lens arrangement range, an error in the conversion coefficient K _a calculated using γ _a and µ or in the actual lens driving amount Δa can be used Focus can be eliminated.

Next, in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 and the ninth embodiment of the present invention, the lens driving amounts focusing from an infinite, focusable lens array to the closest object distance and focusing from the closest, focused lens array to the infinite object distance at the wide-angle end position (F = 36.0), the middle position (F = 50.0) and the telephoto end position (F = 103.0) are calculated from Δa = ΔBf / γ _a (1 - ΔBf / µ), and errors from the actual lens drive amounts are then calculated, with the following values be preserved. It should be noted that the value of the correction coefficient µ with focus from the infinite, in-focus lens arrangement to the closest object distance assumes a value at the object distance (POS-5) and the value of the correction coefficient µ with focus from the closest , the lens arrangement in focus for the infinite object distance assumes a value at the object distance (POS-4).

Embodiment of Japanese Patent Application Laid-Open No. 5-142475

Ninth embodiment

As described above, even if only a pair of a conversion coefficient γ _a and a correction coefficient value µ are set for a given lens arrangement range, an error between the conversion coefficient K _a resulting from γ _a and µ and the lens driving amount Δa for focusing becomes is calculated, small compared to the conventional system, and focusing can be realized with higher accuracy.

For purposes of reference, if there are errors in the lens drive amounts below Focus from the infinite, in-focus lens array to that Object distance (R = 10.0 m) and focusing from the closest one, in focus sensitive arrangement to the object distance (R = 1.0 m) is calculated and compared who get the following results. As seen from these tables that can, the focusing accuracy can be relatively independent of the object stand to be improved.

Embodiment of Japanese Patent Application Laid-Open No. 5-142475

Ninth embodiment

Next, a check is made to see if not just an accurate auto focus will be carried out, but also a so-called manual focus tion in the zoom lens in the ninth embodiment can be achieved.

Table 90 summarizes the amount (ANGLE DA) of a rotation for focusing under one manual focusing using the focus cam (the middle table in Table 82) of the ninth embodiment, the amount X (mm) of a movement, and in the direction of the optical axis of the focusing lens unit according to the amount of rotation for focusing, and the shift amount Bf (mm) of the imaging point when the amount (DX) of movement in the direction of the optical axis is given together.

The upper table in Table 90 summarizes the amount of shift Bf of a map points according to the photographing distances (R = 5.0, 3.0, 2.0, 1.5, 1.0 and 0.85 m) in the respective zooming states of the focus lengths (F = 36.0, 50.0, 60.0, 70.0, 85.0 and 103.0 mm), and the middle table summarizes the values of the amount (ANGLE DA) a rotation to focus together, to achieve an optimal, self state in focus with regard to the respective photographing distances (R = 5.0, 3.0, 2.0, 1.5, 1.0 and 0.85 m) is required. It should be noted that the Rotationsbe sluggish to focus, the values to eliminate any shift in the image point at the wide-angle end position and the telephoto end position are choosing. The table below summarizes the amounts (DX) of a movement in the direction the optical axis, the respective lens units according to the amount (ANGLE  DA) a rotation for focusing in association with the photographing distances (R = 5.0, 3.0, 2.0, 1.5, 1.0 and 0.85 m) in the respective states with the focus lengths (F = 36.0, 50.0, 60.0, 70.0, 85.0 and 103.0 mm) together. In the table below, (F) is the Focus length (mm) of the entire system, (R) is the photographing distance (m) and (DX) is the amount (mm) of movement in the direction of the optical axis of each of them most, the second, the third and the fourth lens unit in order from the right side. It should be noted that the amount of movement in the direction of the optical axis to the object side is represented by a positive value.

Table 90

Displacement amount Bf (mm) of an imaging point and amount (DX) (mm) of a movement for focusing in the ninth embodiment

As can be seen from Table 90, a so-called manual Fo kissing can be obtained since the shift amounts of the mapping point the respective focus lengths and photographing distances is very small, and they fall into within the depth of focus regardless of the zooming state and the photographer distance.

[10. Embodiment]

The 10th embodiment is directed to a zoom lens, which has an arrangement with four units, ie a positive, a negative, a positive and a positive lens unit, and a focus by a negative, second lens unit, as in the embodiment Japanese Patent Application Laid-Open No. 5-142475, previously described in detail as prior art. In this zoom lens, the rotation amount ratio (a _F / a _Z ) of the rotation amount for focusing from the infinite position in focus to the closest position in focus (R = 0.5 m) becomes the amount of rotation Zooming from the wide-angle end position (F = 28.8) to the telephoto end position (F = 103.0) is set so that it is -0.80.

Table 91 below summarizes various paraxial data of an optical system and Data for determining the shape of a focus cam according to the 10th embodiment together.

The upper table in Table 91 summarizes the focus lengths and the symmetry point interval data of the respective lens units of the optical system according to the 10th off form in association with six zooming states (focus lengths F = 28.8, 35.0, 50.0, 70.0, 85.0 and 103.0 mm) together.

The middle table in Table 91 summarizes the wedge scan data when the shape of the focus cam in the second lens unit of the 10th embodiment, which is for Fo kissing is used, expressed by the wedge function given above is the angle of rotation of a rotatable lens barrel and the amount x is associated with movement in the direction of the optical axis.  

Furthermore, the table below in Table 91 summarizes the infinite positions in focus (positions corresponding to infinity) at the respective focus lengths (F = 28.8, 35.0, 50.0, 70.0, 85.0 and 103.0 mm) and the amounts of rotation (amounts of one rotation Focusing) focusing on the respective photographing distances (R = 5.0, 3.0, 2.0, 1.0, 0.7 and 0.5 m) using the focus cam of the 10th embodiment together. In this table, since the amount of rotation for zooming from the wide-angle end position (F = 28.8) to the telephoto end position (F = 103.0) is set to be 10.0, and the amount of rotation for focusing from the infinite, is in Focus position to the closest position in focus (R = 0.5 m) is set to be -8.0, the rotation amount ratio (a _F / a _Z ) of the rotation amount for focusing to the amount of rotation to Zooming in the 10th embodiment -0.80.

Table 91

10th embodiment f = 28.8 to 103.0 (rotation amount ratio: a _F / a _Z = -0.8)

Focus lengths and symmetry point intervals of lens units of the 10th embodiment

Focus cam shape (wedge interpolation sampling point) according to the 10th embodiment

Amount of rotation for zooming and amount of rotation for focusing of the 10th embodiment

(Rotation ratio: a _F / a _Z = -0.8)

Table 92 below summarizes the numerical data values of the cams in the focus end lens unit in the 10th embodiment, this data by Interpolation based on a wedge function based on the scan data of the focus Nockens are calculated, which are summarized in the middle table in Table 91 are. It should be noted that the meaning of the respective symbols in Table 92 are the same as those according to the ninth embodiment.

Table 92

Numerical cam data values of a focusing lens unit in the 10th embodiment

The left table in Table 92 summarizes the numerical data values of the focus cam the 10th embodiment together and the right table in Table 92 summarizes the nu merit data values of the zoom compensation cam of this embodiment together. A value obtained by synthesizing the amounts (2) of a movement in the Direction of the optical axis in the numerical data values of the focus cam and the zoom compensation cam in the range of the amount of rotation (ANGLE = 0.0) on the amount of a rotation (ANGLE = 10.0) is correct the movement point of the second lens unit, which using the Pa raxial data is calculated in the upper table in Table 91.

Tables 93, 94 and 95 below summarize the amount DX (mm) of a movement for focusing in the direction of the optical axis of the focusing lens unit, the magnification β _{x of} the respective lens units, the conversion coefficient γ _x , that of the direction of the optical axis is assigned, the slope (dx / da) of the focus cam and the conversion coefficient γ _a which is assigned to the direction of a rotation at the wide-angle end position (F = 28.8), the middle position (F = 50.0) and the telephoto end position (F = 103.0) , together according to the 10th embodiment. The arrangements of the respective tables and the meaning of the reference symbols are the same as those in the ninth embodiment.

Table 94

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the wide-angle end position (28.8 mm) in the 10th embodiment

Image magnification β _{K of} the lens units at the wide-angle end position (28.8 mm) in the 10th embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the wide-angle end position (28.8 mm) in the 10th embodiment

Slope dx / da of the focus cam at the wide-angle end position (28.8 mm) in the 10th embodiment

Conversion coefficient γ _a , which is assigned to the direction of rotation at the wide-angle end position (28.8 mm) in the 10th embodiment

Table 94

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the center position (50.0 mm) in the 10th embodiment

Image magnification β _{K of} the lens units at the central position (50.0 mm) in the 10th embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the central position (50.0 mm) in the 10th embodiment

Slope dx / da of the focus cam at the middle position (50.0 mm) in the 10th embodiment

Conversion coefficient γ _a , which is assigned to the direction of rotation at the center position (50.0 mm) in the 10th embodiment

Table 95

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the telephoto end position (103.0 mm) in the 10th embodiment

Magnification β _{K of} the lens units at the telephoto end position (103.0 mm) in the 10th embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the telephoto end position (103.0 mm) in the 10th embodiment

Slope dx / da of the focus cam at the telephoto end position (103.0 mm) in the 10th embodiment

Conversion coefficient γ _a , which is assigned to the direction of rotation at the telephoto end position (103.0 mm) in the 10th embodiment

As can be seen from Tables 93, 94 and 95, the conversion coefficient γ _{x associated with} the direction of the optical axis increases, but it decreases the slope (dx / da) of the focus cam as the photographing distance approaches comes to the closest distance at the respective focus lengths. Therefore, as can be seen from these tables, the conversion coefficient γ _{a associated with} the direction of rotation, which is defined as the product of the conversion coefficient γ _x and the slope (dx / da) of the focus cam, decreases. when the photographing distance comes closer to the closest distance, due to the influence of the slope (dx / da) of the focus cam. From Tables 93, 94 and 95, the rate of change from the infinite focus position to the closest focus position of the conversion coefficient γ _{a associated} with the direction of rotation is x0.49 at the wide-angle end position ( F = 28.8), x0.44 at the middle position (F = 50.0) and x0.31 at the telephoto end position (F = 103.0). When the number N of divisions of the focus area is calculated with a change in the conversion coefficient γ _a in the 10th embodiment using the formula (a) and that in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 is compared, the numbers N _W , N _M and N _{T of} the subdivisions at the wide-angle end position, the middle position and the telephoto end position each have the following values:
Embodiment of Japanese Patent Application Laid-Open No. 5-142475
N _W <9.3, N _M <10.1, N _T <8.1
10th embodiment
N _T <3.9, N _M <4.5, N _T <6.5.

Therefore, as can be seen from the comparison above, whether arguably the zoom lens of this embodiment has a larger zoom ratio than that that in the embodiment of Japanese Patent Application Laid-Open No. 5-142475, the values of the numbers N of divisions are reversed degraded.

Also, as described above, in the 10th embodiment, since the rate of change of the conversion coefficient γ _a assigned to the direction of rotation is smaller than that in the conventional system, the values of the numbers N of the divisions become small. For this reason, the number of data of the conversion coefficient γ _a and the correction coefficient µ can be reduced and the storage capacity can be reduced.

Tables 96, 97 and 98 summarize the calculation results of the conversion coefficient K _a and the correction coefficient µ at the wide-angle end position (F = 28.8), the middle position (F = 50.0) and the telephoto end position (F = 103.0) according to the seventh embodiment. The arrangements of the tables and reference symbols are the same as those of the ninth embodiment. The position of the focusing lens in the first pair in the top two tables in each of tables 96, 97 and 98, that is, in the third and fourth columns, is (R, ANGLE) = (0.0, 0.0), and indicates that this position corresponds to the infinitely corresponding position. Similarly, the position of the focusing lens in the fourth pair in the lower two tables in each of tables 96, 97 and 98, ie in the ninth and tenth columns, (R, ANGLE) = (0.5, -8.0), and so on indicates that this position corresponds to the position closest to the one in focus (R = 0.50 m).

Table 96

Conversion coefficient K _a : (rs), γ _a ; (r) assigned the direction of rotation, and correction coefficient µ: (l) at the wide-angle end position (28.8 mm) of the 10th embodiment

f = 28.8 mm

Table 97

Conversion coefficient K _a : (rs), γ _a : (r) assigned to the direction of rotation, and correction coefficient µ: (l) at the central position (50.0 mm) of the 10th embodiment

f = 50.0 mm

Table 98

Conversion coefficient K _a : (rs), γ _a : (r) assigned the direction of rotation and correction coefficient µ: (l) at the telephoto end position (103.0 mm) of the 10th embodiment

f = 103.0 mm

The calculation results of the change rate of K _a with respect to γ _a at the infinite focus position and the closest focus position at the wide-angle end position, the center position and the telephoto end position in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 and in the 10th embodiment of the present invention are as follows.

Embodiment of Japanese Patent Application Laid-Open No. 5-142475

10th embodiment

As described above, in the 10th embodiment, since the rate of change of K _a with respect to γ _{a is} small compared to the conventional system, the contribution of the correction term (ΔBf / µ) in K _a = γ _a (1 - ΔBf / µ) can be further reduced. For this reason, an error of the conversion coefficient K _a calculated based on γ _a and µ or an error from the actual lens driving amount Δa obtained when only a pair of a conversion coefficient value γ _a and a correction coefficient value µ are set can be reduced become.

Next, in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 and the 10th embodiment of the present invention, the lens driving amounts focusing from an infinite focus lens arrangement to the closest object distance and focusing from the closest focus lens arrangement to the infinite object distance at the wide-angle end position, the center position and the telephoto end position are calculated from Δa = ΔBf / γ _a (1 - ΔBf / µ), and errors from the actual lens drive amounts are then calculated to obtain the following values. It should be noted that the value of the correction coefficient µ while focusing from the infinite lens arrangement in focus to the closest object distance takes a value at the object distance (POS-5) and the value of the correction coefficient µ while focusing from the closest, lens arrangement in focus to the infinite object distance assumes a value at the object distance (POS-4).

Embodiment of Japanese Patent Application Laid-Open No. 5-142475

10th embodiment

Also, as described above, in the 10th embodiment, even if only a pair of a conversion coefficient value γ _a and a correction coefficient value µ are set for a given lens arrangement range, an error between the conversion coefficient K _a made from γ _a and µ and the lens drive amount Δa is calculated for focusing, small compared to the conventional system, and focusing can be realized with higher accuracy.

Table 99 summarizes the amount (ANGLE DA) of a rotation for focusing under one manual focusing using the focus cam (the middle table in Table 91) of the 10th embodiment, the amount X (mm) of a movement, namely in the direction of the optical axis of the focusing lens unit corresponding to the Amount of rotation for focusing, and the amount of displacement Bf (mm) of  Imaging point when the amount (DX) of movement in the direction of the optical Axis is given together.

Note that the arrangement of the table and the reference symbols are the same like that in the ninth embodiment. The upper table in Table 99 summarizes the shift amount Bf of an imaging point according to the photographers distances (R = 5.0, 3.0, 2.0, 1.5, 1.0, 0.7 and 0.5 m) in the respective zooming Zu the focus lengths (F = 28.8, 35.0, 50.0, 70.0, 85.0 and 103.0 mm) together and the middle table summarizes the values of the amount (ANGLE DA) of a rotation to Fo kissing together, to achieve an optimal, in focus State with regard to the respective photography distances are required. The lower one Table summarizes the amounts (DX) of a movement in the direction of the optical axis, of the respective lens units according to the amount (ANGLE DA) of a rotation for focusing in association with the respective focus lengths and photographing distances that together.

Table 99

Shift amount Bf (mm) of an imaging point and amount (DX) (mm) of a movement for focusing in the 10th embodiment

As can be seen from Table 99, according to the zoom lens the 10th embodiment, a so-called manual focus can be obtained because the amounts of displacement of the imaging point at the respective focus lengths and Photography distances are very small and they do not fall within the depth of focus depending on the zooming state and the photographing distance.

[11. Embodiment]

The 11th embodiment is directed to a zoom lens which has an arrangement with five units, ie a positive, a negative, a positive, a negative and a positive lens unit, and a focusing by means of a negative, second lens unit as achieved in the embodiment of Japanese Patent Application Laid-Open No. 5-142475, previously described in detail as prior art. In this zoom lens, the rotation amount ratio (a _F / a _Z ) of the rotation amount for focusing from the infinite position in focus to the closest position in focus (R = 0.5 m) becomes the amount of rotation Zoom from the wide-angle end position (F = 28.8) to the telephoto end position (F = 102.0) set to be -0.72.

Table 100 below summarizes various paraxial data of an optical system and Data for determining the shape of a focus cam according to the 11th embodiment together.

The upper table in Table 100 summarizes the focus lengths and the symmetry point inter vall data of the respective lens units of the optical system corresponding to FIG. 11.  Embodiment in association with six zooming states (focus lengths F = 28.8, 35.0, 50.0, 70.0, 85.0 and 102.0 mm) together.

The middle table in Table 100 summarizes the wedge scan data when the shape of the focus cam in the second lens unit of the 11th embodiment, which is related to the Fo kissing is used, expressed by the wedge function given above is the angle of rotation of a rotatable lens barrel and the amount x is associated with movement in the direction of the optical axis.

Furthermore, the lower table in Table 100 summarizes the infinite positions in focus (positions corresponding to infinity) at the respective focus lengths (F = 28.8, 35.0, 50.0, 70.0, 85.0 and 102.0 mm) and the amounts of rotation (amounts of one rotation Focusing) focusing on the respective photographing distances (R = 5.0, 3.0, 2.0,1.0, 0.7 and 0.5 m) using the focus cam of the 11th embodiment together. In this table, since the amount of rotation for zooming from the wide-angle end position (F = 28.8) to the telephoto end position (F = 102.0) is set to be 10.0, and the amount of rotation for focusing from the infinite is in Focus position to the closest position in focus (R = 0.5 m) is set to be -7.2, the rotation amount ratio (a _F / a _Z ) of the rotation amount for focusing to the amount of rotation to Zooming in the 11th embodiment -0.72.

Table 100

11th embodiment f = 28.8 to 102.0 (rotation amount ratio: a _F / a _Z = -0.72)

Focus lengths and symmetry point intervals of lens units of the 11th embodiment

Focus cam shape (wedge interpolation sampling point) according to the 11th embodiment

Amount of rotation for zooming and amount of rotation for focusing of the 11th embodiment

(Rotation ratio: a _F / a _Z = -0.72)

Table 101 below summarizes the numerical data values of the cams in the focus lens unit in the 11th embodiment, and this data by Interpolation based on a wedge function based on the scan data of the focus Cams are calculated, which are summarized in the middle table in Table 100 are. It should be noted that the meaning of the respective reference symbols in Ta belle 101 are the same as those according to the ninth embodiment.

Table 101

Numerical cam data values of a focusing lens unit in the 11th embodiment

The left table in Table 101 summarizes the numerical data values of the focus cam the 11th embodiment together and the right table in Table 101 summarizes the nu merit data values of the zoom compensation cam of this embodiment together. A value obtained by synthesizing the amounts (2) of a movement in the Direction of the optical axis in the numerical data values of the focus cam and the zoom compensation cam in the range of the amount of rotation (ANGLE = 0.0) on the amount of a rotation (ANGLE = 10.0) is correct the movement point of the second lens unit, which using the Pa raxial data in the upper table in Table 100 is calculated.

Tables 102, 103 and 104 below summarize the amount DX (mm) of a movement for focusing in the direction of the optical axis of the focusing lens unit, the magnification β _{x of} the respective lens units, the conversion coefficient γ _x , which is assigned to the direction of the optical axis is the slope (dx / da) of the focus cam and the conversion coefficient γ _a , which is assigned to the direction of rotation at the wide-angle end position (F = 28.8), the middle position (F = 50.0) and the telephoto end position (F = 102.0) , together according to the 11th embodiment. The arrangements of the respective tables and the meaning of the reference symbols are the same as those in the ninth embodiment.

Table 102

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the wide-angle end position (28.8 mm) in the 11th embodiment

Image magnification β _{K of} the lens units at the wide-angle end position (28.8 mm) in the 11th embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the wide-angle end position (28.8 mm) in the 11th embodiment

Slope dx / da of the focus cam at the wide-angle end position (28.8 mm) in the 11th embodiment

Conversion coefficient γ _{a assigned} to the direction of rotation at the wide-angle end position (28.8 mm) in the 11th embodiment

Table 103

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the center position (50.0 mm) in the 11th embodiment

Image magnification β _{K of} the lens units at the central position (50.0 mm) in the 11th embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the central position (50.0 mm) in the 11th embodiment

Slope dx / da of the focus cam at the middle position (50.0 mm) in the 11th embodiment

Conversion coefficient γ _a , which is assigned to the direction of rotation at the center position (50.0 mm) in the 11th embodiment

Table 104

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the telephoto end position (102.0 mm) in the 11th embodiment

Image magnification β _{K of} the lens units at the telephoto end position (102.0 mm) in the 11th embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the telephoto end position (102.0 mm) in the 11th embodiment

Slope dx / da of the focus cam at the telephoto end position (102.0 mm) in the 11th embodiment

Conversion coefficient γ _a , which is assigned to the direction of rotation at the telephoto end position (102.0 mm) in the 11th embodiment

As can be seen from Tables 102, 103 and 104, the conversion coefficient γ _x , which is assigned to the direction of the optical axis, increases at each focus length, but the slope (dx / da) of the focus cam decreases when the Photography distance closer to the closest distance at the respective focus lengths. Therefore, as can be seen from these tables, the conversion coefficient γ _{a associated with} the direction of rotation that is defined as the product of the conversion coefficient γ _x and the slope (dx / da) of the focus cam decreases if the Photography distance comes closer to the closest distance, due to the influence of the slope (dx / da) of the focus cam. From Tables 102, 103 and 104, the rate of change from the infinite focus position to the closest focus position of the conversion coefficient γ _{a associated} with the direction of rotation is x0.55 at the wide-angle end position (F = 28.8), x0.48 at the middle position (F = 50.0) and x0.31 at the telephoto end position (F = 102.0). When the number N of divisions of the focus area is calculated with a change in the conversion coefficient γ _a in the 11th embodiment using the formula (a) and with that in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 is compared, the numbers N _W , N _M and N _{T of} the subdivisions at the wide-angle end position, the middle position and the telephoto end position each have the following values:
Embodiment of Japanese Patent Application Laid-Open No. 5-142475
N _W <9.3, N _M <10.1, N _T <8.1,
11th embodiment
N _W <3.2, N _M <4.0, N _T <6.3.

Therefore, although the zoom lens of this embodiment becomes larger Zoom ratio than that in the Japanese embodiment. disclosed Patent application No. 5-142475 has the values of the numbers N of divisions conversely lowered.

Also, as described above, in the 11th embodiment, since the rate of change of the conversion coefficient γ _{a assigned} to the direction of rotation is smaller than that in the conventional system, the values of the numbers N of the divisions become small. For this reason, the number of data of the conversion coefficient γ _a and the correction coefficient µ can be reduced and the storage capacity can be reduced.

Tables 105, 106 and 107 summarize the calculation results of the conversion coefficient K _a and the correction coefficient µ at the wide-angle end position (F = 28.8), the middle position (F = 50.0) and the telephoto end position (F = 102.0) according to the 11th embodiment. The arrangements of the tables and reference symbols are the same as those of the ninth embodiment. The position of the focusing lens in the first pair in the top two tables, in each of tables 105, 106 and 107, ie in the third and fourth columns, is (R, ANGLE) = (0.0, 0.0) and it indicates that this position corresponds to the infinitely corresponding position. Similarly, the position of the focusing lens in the fourth pair in the lower two tables in each of tables 105, 106 and 107, ie in the ninth and tenth columns, (R, ANGLE) = (0.5, -7.2), and it indicates that this position corresponds to the closest position in focus (R = 0.50 m) corresponding position.

Table 105

Conversion coefficient K _a : (rs), γ _a : (r) assigned to the direction of rotation and correction coefficient µ: (l) at the wide-angle end position (28.8 mm) of the 11th embodiment

f = 28.8 mm

Table 106

Conversion coefficient K _a : (rs), γ _a : (r) assigned to the direction of rotation, and correction coefficient µ: (l) at the center position (50.0 mm) of the 11th embodiment

f = 50.0 mm

Table 107

Conversion coefficient K _a : (rs), γ _a : (r) assigned to the direction of rotation and correction coefficient µ: (l) at the telephoto end position (102.0 mm) of the 11th embodiment

f = 102.0 mm

The calculation results of the change rate of K _a with respect to γ _a at the infinite focus position and the closest focus position at the wide-angle end position, the center position and the telephoto end position in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 and in the 11th embodiment of the present invention are as follows.

Embodiment of Japanese Patent Application Laid-Open No. 5-142475

11th embodiment

As described above, in the 11th embodiment, since the rate of change of K _a with respect to γ _{a is} small compared to the conventional system, the contribution of the correction term (ΔBf / µ) in K _a = γ _a (1 - ΔBf / µ) can be further reduced. For this reason, an error of the conversion coefficient K _a calculated based on γ _a and µ, or an error from the actual lens driving amount Δa obtained when only a pair of a conversion coefficient value γ _a and a correction coefficient value µ is set, be reduced.

Next, in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 and the 11th embodiment of the present invention, the lens drive amounts focusing from an infinite focus lens arrangement to the closest object distance and focusing from the closest focus lens arrangement to the infinite object distance at the wide-angle end position, the center position and the telephoto end position are calculated from Δa = ΔBf / γ _a (1 - ΔBf / µ), and errors from the actual lens drive amounts are then calculated to obtain the following values. It should be noted that the value of the correction coefficient µ while focusing from the infinite lens arrangement in focus to the closest object distance takes a value at the object distance (POS-5) and the value of the correction coefficient µ while focusing from the closest, lens arrangement in focus to the infinite object distance assumes a value at the object distance (POS-4).

Embodiment of Japanese Patent Application Laid-Open No. 5-142475

11th embodiment

Also, as described above, in the 11th embodiment, even if only a pair of a conversion coefficient value γ _a and a correction coefficient value µ are set for a given lens arrangement range, an error between the conversion coefficient K _a that is made up of γ _a and the lens drive amount Δa calculated for focusing is small compared to the conventional system, and focusing can be realized with higher accuracy.

Table 108 summarizes the amount (ANGLE DA) of a rotation for focusing under one manual focusing using the focus cam (the middle table in  Table 91) of the 11th embodiment, the amount X (mm) of a movement, namely in the direction of the optical axis of the focusing lens unit corresponding to the Amount of a rotation for focusing, and the shift amount Bf (mm) of the Ab education point when the amount (DX) of a movement in the direction of the optical Axis is given together.

It should be noted that the arrangement of the table and the reference symbols are the same like those in the ninth embodiment. The upper table in Table 108 summarizes the shift amount Bf of an imaging point according to the photographers distances (R = 5.0, 3.0, 2.0, 1.5, 1.0, 0.7 and 0.5 m) in the respective zooming Zu the focus lengths (F = 28.8, 35.0, 50.0, 70.0, 85.0 and 102.0 mm) together and the middle table summarizes the values of the amount (ANGLE DA) of a rotation to Fo kissing together, to achieve an optimal, in focus State with regard to the respective photography distances are required. The lower one Table summarizes the amounts (DX) of a movement in the direction of the optical axis, of the respective lens units according to the amount (ANGLE DA) of a rotation for focusing in association with the respective focus lengths and photographing distances that together.

Table 108

Shift amount Bf (mm) of an imaging point and amount (DX) (mm) of a movement for focusing in the 11th embodiment

As can be seen from table 108, according to the zoom lens the 11th embodiment, a so-called manual focus can be obtained because the amounts of displacement of the imaging point at the respective focus lengths and Photography distances are very small and they do not fall within the depth of focus depending on the zooming state and the photographing distance.

[12. Embodiment]

The 12th embodiment is directed to a zoom lens having a four unit arrangement, ie, positive, negative, positive and negative lens units, and focusing by a positive third lens unit as in the embodiment of FIG Japanese Patent Application Laid-Open No. 5-142475, previously described in detail as prior art. In this zoom lens, the rotation amount ratio (a _F / a _Z ) of the rotation amount for focusing from the infinite position in focus to the closest position in focus (R = 1.2 m) becomes the amount of rotation Zooming from the wide-angle end position (F = 72.0) to the telephoto end position (F = 200.0) is set so that it is -0.75.

Table 109 below summarizes various paraxial data of an optical system and Data for determining the shape of a focus cam according to the 12th embodiment together.  

The upper table in Table 109 summarizes the focus lengths and the symmetry point inter vall data of the respective lens units of the optical system according to the 12th Embodiment in association with six zooming states (focus lengths F = 72.0, 105.0, 135.0, 150.0 and 200.0 mm) together.

The middle table in Table 109 summarizes the wedge scan data when the shape of the focus cam in the second lens unit of the 12th embodiment, which for Fo kissing is used, expressed by the wedge function given above is the angle of rotation of a rotatable lens barrel and the amount x is associated with movement in the direction of the optical axis.

Furthermore, the lower table in Table 109 summarizes the infinite positions in focus (positions corresponding to infinity) at the respective focus lengths (F = 72.0, 105.0, 135.0, 150.0 and 200.0 mm) and the amounts of rotation (amounts of a rotation for focusing) focusing on the respective photographing distances (R = 5.0, 4.0, 3.0, 2.0, 1.5 and 1.2 m) using the focus cam of the 12th embodiment together. In this table, since the amount of rotation for zooming from the wide-angle end position (F = 72.0) to the telephoto end position (F = 200.0) is set to be 10.0, and the amount of rotation for focusing from the infinite, is in Focus position to the closest position in focus (R = 1.2 m) is set to be -7.5, the rotation amount ratio (a _F / a _Z ) of the rotation amount for focusing to the amount of rotation to Zooming in the 12th embodiment -0.75.

Table 109

12th embodiment f = 72.0 to 200.0 (rotation amount ratio: a _F / a _Z = -0.75)

Focus lengths and symmetry point intervals of lens units of the 12th embodiment

Focus cam shape (wedge interpolation sampling point) according to the 12th embodiment

Amount of rotation for zooming and amount of rotation for focusing of the 12th embodiment

(Rotation amount ratio: a _F / a _Z = -0.75)

Table 110 below summarizes the numerical data values of the cams in the focus end lens unit in the 12th embodiment, and this data by Interpolation based on a wedge function based on the scan data of the focus Nockens are calculated, which are summarized in the middle table in Table 109 are. It should be noted that the meaning of the respective reference symbols in Ta belle 110 are the same as those according to the ninth embodiment.

Table 110

Numerical cam data values of a focusing lens unit in the 12th embodiment

The left table in Table 110 summarizes the numerical data values of the focus cam the 12th embodiment together and the right table in Table 110 summarizes the nu merit data values of the zoom compensation cam of this embodiment together. A value obtained by synthesizing the amounts (3) of a movement in the Direction of the optical axis in the numerical data values of the focus cam and the zoom compensation cam in the range of the amount of rotation (ANGLE = 0.0) on the amount of a rotation (ANGLE = 10.0) is correct the movement point of the second lens unit, which using the Pa raxial data is calculated in the upper table in Table 109.

Tables 111, 112 and 113 below summarize the amount DX (mm) of a movement for focusing in the direction of the optical axis of the focusing lens unit, the magnification β _{x of} the respective lens units, the conversion coefficient γ _x , the direction of the optical Assigned to the axis, the slope (dx / da) of the focus cam and the conversion coefficient γ _a , which corresponds to the direction of a rotation at the wide-angle end position (F = 72.0), the middle position (F = 135.0) and the telephoto end position (F = 200.0) is assigned according to the 12th embodiment in each case together. The arrangements of the respective tables and the meaning of the reference symbols are the same as those in the ninth embodiment.

Table 111

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the wide-angle end position (72.0 mm) in the 12th embodiment

Image magnification β _{K of} the lens units at the wide-angle end position (72.0 mm) in the 12th embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the wide-angle end position (72.0 mm) in the 12th embodiment

Slope dx / da of the focus cam at the wide-angle end position (72.0 mm) in the 12th embodiment

Conversion coefficient γ _a , which is assigned to the direction of rotation at the wide-angle end position (72.0 mm) in the 12th embodiment

Table 112

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the center position (135.0 mm) in the 12th embodiment

Magnification β _{K of} the lens units at the central position (135.0 mm) in the 12th embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the central position (135.0 mm) in the 12th embodiment

Slope dx / da of the focus cam at the middle position (135.0 mm) in the 12th embodiment

Conversion coefficient γ _a , which is assigned to the direction of rotation at the center position (135.0 mm) in the 12th embodiment

Table 113

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the telephoto end position (200.0 mm) in the 12th embodiment

Image magnification β _{K of} the lens units at the telephoto end position (200.0 mm) in the 12th embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the telephoto end position (200.0 mm) in the 12th embodiment

Slope dx / da of the focus cam at the telephoto end position (200.0 mm) in the 12th embodiment

Conversion coefficient γ _a , which is assigned to the direction of rotation at the telephoto end position (200.0 mm) in the 12th embodiment

As can be seen from Tables 111, 112 and 113, the conversion coefficient γ _x , which is assigned to the direction of the optical axis, is not subject to any change at the wide-angle end position and the middle position, but it increases at the telephoto end position when the photographing distance comes closer to the closest distance, and the slope (dx / da) of the focus cam decreases as the photography distance gets closer to the closest distance at the respective focus lengths. Therefore, as can be seen from these tables, the conversion coefficient γ _{a associated with} the direction of rotation that is defined as the product of the conversion coefficient γ _x and the slope (dx / da) of the focus cam decreases if the Photography distance comes closer to the closest distance, due to the influence of the slope (dx / da) of the focus cam. From Tables 111, 112 and 113, the rate of change from the infinite, in-focus position to the closest, in-focus position of the conversion coefficient γ _{a associated} with the direction of rotation is x0.42 at the wide-angle end position (F = 72.0), x0.41 at the middle position (F = 135.0) and x0.39 at the telephoto end position (F = 200.0). When the number N of divisions of the focus area is calculated under a change in the conversion coefficient γ _a in the 12th embodiment using the formula (a) and with that in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 is compared, the numbers N _W , N _M and N _{T of} the divisions at the wide-angle end position, the middle position and the telephoto end position each have the following values:
Embodiment of Japanese Patent Application Laid-Open No. 5-142475
N _W <9.3, N _M <10.1, N _T <8.1
12th embodiment
N _W <4.8, N _M <4.9, N _T <5.1.

Also, as described above, in the 12th embodiment, since the rate of change of the conversion coefficient γ _{a assigned} to the direction of rotation is smaller than that in the conventional system, the values of the numbers N of the divisions become small. For this reason, the number of data of the conversion coefficient γ _a and the correction coefficient µ can be reduced and the storage capacity can be reduced.

Tables 114, 115 and 116 summarize the calculation results of the conversion coefficient K _a and the correction coefficient μ at the wide-angle end position (F = 72.0), the middle position (F = 135.0) and the telephoto end position (F = 200.0) according to the 12th embodiment. The arrangements of the tables and reference symbols are the same as those of the ninth embodiment. The position of the focusing lens in the first pair in the top two tables in each of tables 114, 115 and 116, that is, in the third and fourth columns, is (R, ANGLE) = (0.0,0.0) and it indicates that this position corresponds to the infinitely corresponding position. Similarly, the position of the focusing lens in the fourth pair in the lower two tables in each of tables 114, 115 and 116, ie in the ninth and tenth columns, (R, ANGLE) = (1.2, -7.5), and it indicates that this position corresponds to the position closest to the position in focus (R = 1.2 m).

Table 114

Conversion coefficient K _a : (rs), γ _a : (r) assigned to the direction of rotation, and correction coefficient µ: (l) at the wide-angle end position (72.0 mm) of the 12th embodiment

f = 72.0 mm

Table 115

Conversion coefficient K _a : (rs), γ _a : (r) assigned to the direction of rotation, and correction coefficient µ: (l) at the central position (135.0 mm) of the 12th embodiment

f = 135.0 mm

Table 116

Conversion coefficient K _a : (rs), γ _a : (r) assigned to the direction of rotation and correction coefficient µ: (l) at the telephoto end position (200.0 mm) of the 12th embodiment

f = 200.0 mm

The calculation results of the change rate of K _a with respect to γ _a at the infinite focus position and the closest focus position at the wide-angle end position, the center position and the telephoto end position in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 and in the 12th embodiment of the present invention are as follows.

Embodiment of Japanese Patent Application Laid-Open No. 5-142475

12th embodiment

2 U = 45 WI = 166 TI = TAB <

As described above, also in the 12th embodiment, since the rate of change of K _a with respect to γ _{a is} small compared to the conventional system, the contribution of the correction term (ΔBf / µ) in K _a = γ _a (1 - ΔBf / µ) can be further reduced. For this reason, an error of the conversion coefficient K _a calculated based on γ _a and µ, or an error from the actual lens driving amount Δa obtained when only a pair of a conversion coefficient value γ _a and a correction coefficient value µ is set, be reduced.

Next, in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 and the 12th embodiment of the present invention, the lens driving amounts focusing from an infinite focus lens array to the closest object distance and focusing from the closest focus lens array to the infinite object distance from the wide-angle end position, the center position and the telephoto end position is calculated from Δa = ΔBf / γ _a (1 - ΔBf / µ), and errors from the actual lens drive amounts are then calculated, the following values being obtained. It should be noted that the value of the correction coefficient µ while focusing from the infinite lens arrangement in focus to the closest object distance takes a value at the object distance (POS-5) and the value of the correction coefficient µ while focusing from the closest, im Focus lens arrangement to the infinite object distance takes a value at the object distance (POS-4).

Embodiment of Japanese Patent Application Laid-Open No. 5-142475

12th embodiment

Also, as described above, in the 12th embodiment, even if only a pair of a conversion coefficient value γ _a and a correction coefficient value µ are set for a given lens arrangement range, an error between the conversion coefficient K _a made from γ _a and µ and the lens drive amount Δa for focusing is small, compared with the conventional system, and focusing can be realized with higher accuracy.

Table 117 summarizes the amount (ANGLE DA) of a rotation for focusing under one manual focusing using the focus cam (the middle table in Table 109) of the 12th embodiment, the amount X (mm) of a movement, namely in the direction of the optical axis of the focusing lens unit corresponding to the Amount of a rotation for focusing, and the shift amount Bf (mm) of the Ab education point when the amount (DX) of a movement in the direction of the optical Axis is given together.

It should be noted that the arrangement of the table and the reference symbols are the same like those in the ninth embodiment. The top table in table 117 sums the shift amount Bf of a mapping point according to the photo graphing distances (R = 5.0, 4.0, 3.0, 2.0, 1.5 and 1.2 m) in the respective zooming areas the focus lengths (F = 72.0, 105.0, 135.0, 150.0 and 200.0 mm) together and the middle table summarizes the values of the amount (ANGLE DA) of a rotation to the focus together to achieve an optimal focus that is in focus stands with regard to the respective photography distances are required. The lower ta belle summarizes the amounts (DX) of a movement in the direction of the optical axis, the respective lens units according to the amount (ANGLE DA) of a rotation Focusing in association with the respective focus lengths and photographing distances together.  

Table 117

Shift amount Bf (mm) of an imaging point and amount (DX) (mm) of a movement for focusing in the 12th embodiment

As can be seen from Table 117, according to the zoom lens the 12th embodiment, a so-called manual focus can be obtained because the amounts of displacement of the imaging point at the respective focus lengths and Photography distances are very small and they do not fall within the depth of focus depending on the zooming state and the photographing distance.

In the 12th embodiment, based on Tables 111 and 112, the conversion coefficient γ _{x associated with} the direction of the optical axis increases slightly at the wide-angle end position and the center position when the photographing distance comes closer to the closest distance. Therefore, since the conversion coefficient γ _a associated with the direction of rotation is defined as the product of the conversion coefficient γ _x and the slope (dx / da) of the focus cam, it can be seen that the slope (dx / da) of the focus cam is preferably increased when the photographing distance comes closer to the closest distance, as in the embodiment of Japanese Patent Application Laid-Open No. 5-142475. However, since the conversion coefficient γ _{x associated with} the direction of the optical axis greatly increases at the telephoto end position compared to the wide-angle end position of the center position, the slope (dx / da) of the focus cam preferably decreases when the photographing distance is closer comes the closest distance, similar to the present invention, taking into account the rate of change of the conversion coefficient γ _a , which is assigned to the direction of rotation as a whole.

[13. Embodiment]

The 13th embodiment is directed to a zoom lens which has an arrangement with five units, ie a positive, a negative, a positive, a negative and a positive lens unit, and a focusing by means of a negative, second lens unit. In this zoom lens, the rotation amount ratio (a _F / a _Z ) of the rotation amount for focusing from the infinite position in focus to the closest position in focus (R = 0.8 m) becomes the amount of rotation for zooming from the wide-angle end position (F = 28.7) to the telephoto end position (F = 131.0) so that it is -0.85.

Table 118 below summarizes various paraxial data of an optical system and Data for determining the shape of a focus cam according to the 13th embodiment together.

The upper table in Table 118 summarizes the focus lengths and the symmetry point inter vall data of the respective lens units of the optical system according to the 13th Embodiment in association with six zooming states (focus lengths F = 28.7, 35.0, 50.0, 70.0, 105.0 and 131.0 mm) together.

In these tables, F1, F2, F3, F4 and F5 are the respective focus lengths of the first, the second, third, fourth and fifth lens units, and D1, D2, D3, D4 and D5 are the symmetry point interval between the first and the second, respectively Lens unit, the symmetry point interval between the second and third lines unit, the symmetry point interval between the third and fourth lenses the symmetry point interval between the fourth and fifth lens units and the symmetry point interval between the fifth lens unit and one past agreed image level in the six zooming states (focus lengths F = 28.7, 35.0, 50.0, 70.0, 105.0 and 131.0 mm).  

The middle table in Table 118 summarizes the wedge scan data when the shape (a curve g _2F in Fig. 5B) of the focus cam in the second lens unit of the 13th embodiment used for focusing is expressed by the above wedge function is associated with the angle of rotation of a rotatable lens barrel and the amount x of movement in the direction of the optical axis.

Furthermore, the table below in Table 118 summarizes the infinite positions in focus (positions corresponding to infinity) at the respective focus lengths (F = 28.7, 35.0, 50.0, 70.0, 105.0 and 131.0 mm) and the amounts of rotation (amounts of a rotation for focusing) focusing on respective photographing distances (R = 5.0, 3.0, 2.0, 1.5, 1.0 and 0.8 m) using the focus cam of the 13th embodiment together. In this table, since the rotation amount to the zoo men from the wide-angle end position (F = 28.7) to the telephoto end position (F = 131.0) is set to be 10.0, and the amount of rotation to focus from the infinite is in focus position to the closest position in focus (R = 0.8 m) is set to be -8.5, the rotation ratio (a _F / a _Z ) of the rotation amount for focusing to the amount of rotation for zooming in the 13th embodiment -0.85.

Table 118

13th embodiment f = 28.7 to 131.0 (rotation amount ratio: a _F / a _Z = -0.85)

Focus lengths and symmetry point intervals of lens units of the 13th embodiment

Focus cam shape (wedge interpolation sampling point) according to the 13th embodiment

Amount of rotation for zooming and amount of rotation for focusing of the 13th embodiment

(Rotation amount ratio: a _F / a _Z = -0.85)

Table 119 below summarizes the numerical data values of the cams in the focus end lens unit in the 13th embodiment, and this data by Interpolation based on a wedge function based on the scan data of the focus Nockens are calculated, which are summarized in the middle table in Table 118 are. In this table, (ANGLE) is the rotation angle of the rotatable lens barrel, (2) is the amount (mm) of movement in the direction of the optical axis of the two th lens unit, and (F) is the focal length (mm) of the entire system in one finite state in focus according to the amount (ANGLE) ei a rotation.

Table 119

Numerical cam data values of a focusing lens unit in the 13th embodiment

The left table in Table 119 summarizes the numerical data values of the focus cam of the 13th embodiment and the right table in Table 119 summarizes the numerical data values of the zoom compensation cam of this embodiment. A value obtained by synthesizing the amounts (2) of movement in the direction of the optical axis in the numerical data values of the focus cam and the zoom compensation cam in the range from the amount of rotation (ANGLE = 0.0) to the amount of rotation (ANGLE = 10.0) is obtained agrees with the movement point (a curve g₂ in FIG. 5A) of the second lens unit, which is calculated using the paraxial data in the upper table in Table 118.

Therefore, the zoom compensation cam (a curve g _2H in Fig. 5B) is determined by subtracting the focus cam (the curve g _2F in Fig. 5B) from the movement point (curve g₂ in Fig. 5A) while zooming the second lens unit , which is determined by the paraxial data in the upper table in Table 118.

FIGS. 5A and 5B and Fig. 6 will be described briefly below.

Fig. 5A shows the paraxial arrangement and the moving positions while zooming the zoom lens according to the 13th embodiment, and Fig. 5B shows the shapes of the focus cam and the zoom compensation cam of the second lens unit of this embodiment. Like the Fig. 5A and 5B show, G1, G2, G3, G4 and G5 each represent the first, second, third, fourth and fifth lens units, and g₁, g₂, g₃, g₄ and g₅ each represent the movement points while zooming in first, second, third, fourth and fifth lens unit. In addition, g _2F and g _2H represent the shapes of the focus cam and the zoom compensation cam of the second lens unit, respectively. As described above, a shape obtained by synthesizing the Focus cam g _2F and the zoom compensation cam g _{2H of} the second lens unit is obtained with the movement point g₂ of the second lens unit.

Fig. 6 shows a view for explaining the shape of the focus cam g _{2F of} the 13th embodiment. As FIG. 6 shows, (f = 28.7; R = un) and (f = 28.7; R = 0.80) each place the positions in focus at the infinite and the closest distance (R = 0.80 m) at the Wide-angle end position and coordinate positions (x; a) on the focus cam are (x; a) = (0; 0) and (x; a) = (0.821; -8.5). On the other hand, (f = 131; R = un) and (f = 131; R = 0.80) represent the positions in focus at the infinite and the closest distance (R = 0.80 m) at the telephoto end position, and coordinate positions (x; a) on the focus cam are (x; a) = (-2.775; 10) and (x; a) = (-0.233; 1.5).

While zooming from the wide-angle end position to the telephoto end position, the second lens unit on the focus cam g _2F moves from the coordinate position (0; 0) to the coordinate position (-2.775; 10) for an infinite object and from the coordinate position (0.821; - 8.5) to the coordinate position (-0.233; 1.5) for a closest object distance. Therefore, the second lens unit 10.0 moves in the direction of rotation (the direction of an axis a) in both cases. On the other hand, while focusing from the infinite arrangement to the closest object distance, the second lens unit on the focus cam g _2F moves from the coordinate position (0; 0) to the coordinate position (0.821; -8.5) at the wide-angle end position and from the coordinate position ( -2.775; 10) to the coordinate position (-0.233; 1.5) at the telephoto end position. Therefore, the second lens unit moves -8.5 in the direction of rotation (the direction of the axis a) at these ends. In contrast, in the direction of the optical axis (the direction of an axis x), the second lens unit moves 0.821 at the wide-angle end position and 2.543 at the telephoto end position.

Since the shape of the focus cam g _{2F is} obtained by interpolating the coordinates (f = 28.7; R = 0.80), (f = 28.7; R = un), (f = 131; R = 0.80) and (f = 131; R = un) is determined by the wedge function, the change in the slope (dx / da) of the focus cam g _2F becomes larger since the absolute value of the x coordinate of (f = 28.7; R = 0.80) is smaller or there the absolute value of the x coordinate of (f = 131; R = un) is larger. More specifically, since the ratio (Δx _TR / Δx _WR ) between the amounts Δx _TR and Δx _{WR of} the movement in the optical axis direction of the focusing lens unit is for focusing from the infinite position to the closest distance position at the wide-angle end position or the telephoto end position is required, the change in the slope (dx / da) of the focus cam is larger.

Tables 120, 121 and 122 below summarize the amount DX (mm) of a movement for focusing in the direction of the optical axis of the focusing lens unit, the magnification β _{x of} the respective lens units, the conversion coefficient γ _x , which is assigned to the direction of the optical axis is the slope (dx / da) of the focus cam and the conversion coefficient γ _a , which is assigned to the direction of rotation at the wide-angle end position (F = 28.7), the middle position (F = 70.0) and the telephoto end position (F = 131.0) , together according to the ninth embodiment. In these tables, (R) on the left is the photographing distance (m), (ANG) is the amount of rotation on the focus cam focusing on the respective photographing distances and 1), 2), 3), 4) and 5) The right, the first, the second, the third, the fourth and the fifth lens unit represent each. Also in these tables, the first table summarizes the amount DX (mm) of a movement for focusing in the direction of the optical axis under focusing to the respective photography distances (R = 10.0, 5.0, 3.0, 2.0, 1.5, 1.0 and 0.80 m) (note that the movement to the object side is positive) together. The second table summarizes the image magnifications β _{x of} the respective lens units in a state in focus at the respective photographing distances (R = 10.0, 5.0, 3.0, 2.0, 1.5, 1.0 and 0.80 m). The third table summarizes the conversion coefficient γ _x , which is assigned to the direction of the optical axis of the focusing lens unit in a state in focus at the respective photographing distances (R = 10.0, 5.0, 3.0, 2.0, 1.5,1.0 and 0.80 m), together. Furthermore, the fourth table summarizes the slope (dx / da) of the focus cam at the positions on the focus cam corresponding to a state in focus at the respective photographing positions (R = 10.0, 5.0, 3.0, 2.0, 1.5, 1.0 and 0.80 m) together and the fifth table summarizes the conversion coefficient γ _a , the direction of rotation of the focusing lens unit in a state in focus at the respective photographing distances (R = 10.0, 5.0, 3.0, 2.0, 1.50, 1.0 and 0.80 m) is assigned together.

Table 120

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the wide-angle end position (28.7 mm) in the 13th embodiment

Image magnification β _{K of} the lens units at the wide-angle end position (28.7 mm) in the 13th embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the wide-angle end position (28.7 mm) in the 13th embodiment

Slope dx / da of the focus cam at the wide-angle end position (28.7 mm) in the 13th embodiment

Conversion coefficient γ _a , which is assigned to the direction of rotation at the wide-angle end position (28.7 mm) in the 13th embodiment

Table 121

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the center position (70.0 mm) in the 13th embodiment

Image magnification β _{K of} the lens units at the central position (70.0 mm) in the 13th embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the central position (70.0 mm) in the 13th embodiment

Slope dx / da of the focus cam at the middle position (70.0 mm) in the 13th embodiment

Conversion coefficient γ _a , which is assigned to the direction of rotation at the center position (70.0 mm) in the 13th embodiment

Table 122

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the telephoto end position (131.0 mm) in the 13th embodiment

Image magnification β _{K of} the lens units at the telephoto end position (131.0 mm) in the 13th embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the telephoto end position (131.0 mm) in the 13th embodiment

Slope dx / da of the focus cam at the telephoto end position (131.0 mm) in the 13th embodiment

Conversion coefficient γ _a , which is assigned to the direction of rotation at the telephoto end position (131.0 mm) in the 13th embodiment

As can be seen from tables 120, 121 and 122, the conversion coefficient γ _x , which is assigned to the direction of the optical axis, increases at each focus length, but the slope (dx / da) of the focus cam decreases as the photographing distance becomes closer comes to the closest distance. Therefore, as can be seen from these tables, the conversion coefficient γ _{a associated with} the direction of rotation, which is defined as the product of the conversion coefficient γ _x and the slope (dx / da) of the focus cam, decreases the photographing distance comes closer to the closest distance by the influence of the slope (dx / da) of the focus cam, contrary to the embodiment of Japanese Patent Application Laid-Open No. 5-142475.

As described above, when the ratio (Δx _TR / Δx _WR ) between the amounts Δx _TR and Δx _WR of movement in the optical axis direction of the focusing lens unit, it becomes necessary to focus from the infinite position to the closest distance position is at the wide-angle end position and the telephoto end position is large, the degree of decrease in the slope (dx / da) of the focus cam is also large. For this reason, the conversion coefficient γ _a , which is assigned to the direction of rotation, further decreases under the influence of the slope (dx / da) of the focus cam when the photographing distance comes closer to the closest distance.

From Tables 120, 121 and 122, the rate of change from the infinite focus position to the closest focus position of the conversion coefficient γ _{a associated} with the direction of rotation is x0.47 at the wide-angle end position (F = 28.7), x0.38 at the middle position (F = 70.0) and x0.37 at the telephoto end position (F = 131.0). When the number N of divisions of the focus area is calculated with a change in the conversion coefficient γ _a in the ninth embodiment using the formula (a) and with that in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 is compared, the numbers N _W , N _M and N _{T of} the subdivisions at the wide-angle end position, the middle position and the telephoto end position each have the following values:
Embodiment of Japanese Patent Application Laid-Open No. 5-142475
N _W <9.3, N _M <10.1, N _T <8.1
13th embodiment
N _W <4.2, N _M <5.3, N _T <5.5.

Therefore, as from a comparison with the previously calculated values in the Embodiment of Japanese Patent Application Laid-Open No. 5-142475 he can be clearly understood, although the zoom lens in this embodiment form has a larger zoom ratio than that of the Japanese, disclosed filed patent application No. 5-142475, the values of the numbers N of divisions degraded.  

As described above, in the zoom lens of the 13th embodiment, since the rate of change from the infinite focus position to the closest focus position, the conversion coefficient γ _{a associated with} the rotation direction can be much smaller than that in the embodiment of Japanese Patent Application Laid-Open No. 5-142475, the number of data of the conversion coefficient γ _a and the correction coefficient µ can be reduced, and the storage capacity can be reduced.

Tables 123, 124 and 125 summarize the calculation results of the conversion coefficient K _a and the correction coefficient µ at the wide-angle end position (F = 28.7), the middle position (F = 70.0) and the telephoto end position (F = 131.0) according to the 13th embodiment. In these tables, (R) is the object distance (m), (ANG) is the rotation amount for focusing from the infinitely corresponding position on the focus cam, (r) is the conversion coefficient γ _a in the direction of rotation, (rs) the conversion coefficient K _a , (bf) is the defocus amount (mm) and (l) is the correction coefficient µ. Each table has a matrix structure, and eight rows in the vertical direction indicated by (POS) represent the object positions (R = 10.0, 5.0, 3.0, 2.0, 1.5, 1.0 and 0.80 mm) and four pairs ( R, ANGLE) in the horizontal direction represent the lens arrangements of the focusing lens unit.

More specifically, the position of the focusing lens in the first pair in the top two tables in each of tables 123, 124 and 125, that is, in the third and fourth columns, (R, ANGLE) = (0.0, 0.0), and it indicates that this position corresponds to the position finally corresponding to un. Therefore, the third column (r) in the first table represents the value of the conversion coefficient γ _a in the rotation direction when the focusing lens unit is focused on an infinite object, and the fourth column (rs) represents the value of the conversion coefficient K _a when the focussing lens unit is moved from a state in focus on an infinite object to a state in focus at an object distance in the second column. Furthermore, the third column (bf) in the second table represents the defocus amount ΔBf from a certain imaging position when the position of the focusing lens unit corresponds to the infinitely corresponding position and an object is arranged at an object distance in the second column, and the fourth column (l) represents the value of the correction coefficient µ when the focusing lens unit is moved from a state in focus on an infinite object to a state in focus on the object distance in the second column.

Similarly, the position of the focusing lens unit in the fourth pair in the lower two tables in each of tables 123, 124 and 125, ie in the ninth and tenth columns, (R, ANGLE) = (0.80, -8.5), and it indicates that this position corresponds to the position corresponding to the closest position in focus (R = 0.80 m). Therefore, the ninth column (r) in the third table represents the value of the conversion coefficient γ _a in the rotation direction when the focusing lens unit is focused on a closest object distance (R = 0.80 m) and the 10th column (rs) represents the value of the conversion coefficient K _a when the focusing lens unit is moved from a state in focus to the closest object distance (R = 0.80 m) to a state in focus at an object distance in the second column. Furthermore, the ninth column (bf) in the fourth table represents the defocus amount ΔBf from a predetermined imaging position if the position of the focusing lens unit corresponds to the position corresponding to the closest position and the object is arranged at an object distance in the second column, and the tenth column (1) represents the value of the correction coefficient µ when the focusing lens unit changes from a state in focus at the closest object distance (R = 0.80 m) to a state in focus at the object distance in the second column is moved.

As described above, since the conversion coefficient in the rotation direction is calculated by K _a = ΔBf / (1 - K _a / γ _a ) (where Δa: the rotation amount for focusing), and the correction coefficient µ by µ = ΔBf / (1 - K _a / γ _a ) is calculated, the value of the conversion coefficient K _a (eighth row, fourth column in the first table: -0.139) when the focusing lens unit increases from a state in focus on the infinite object in a state in focus at the object distance (R = 0.80 m), calculated in Table 123 by K _a = 1.18 / -8.5 = -0.139 using ΔBf = 1.18 and Δa = -8.5. On the other hand, the value of the correction coefficient (eighth row, fourth column in the second table: 4.26) is calculated as µ = 4.26 using ΔBf = 1.18, K _a = -0.139 and γ _a = -0.193.

Table 123

Conversion coefficient K _a : (rs), γ _a : (r) assigned to the direction of rotation, and correction coefficient µ: (l) at the wide-angle end position (28.7 mm) of the 13th embodiment

f = 28.7 mm

Table 124

Conversion coefficient K _a : (rs), γ _a : (r) assigned to the direction of rotation, and correction coefficient µ: (l) at the center position (70.0 mm) of the 13th embodiment

f = 70.0 mm

Table 125

Conversion coefficient K _a : (rs), γ _a : (r) assigned to the direction of rotation and correction coefficient µ: (l) at the telephoto end position (131.0 mm) of the 13th embodiment

f = 131.0 mm

As can be seen from Tables 123, 124 and 125 above, when there is a change in the conversion coefficient K _a : (rs) (e.g. the fourth column in the first table) on a given lens arrangement (e.g. at the infinite, in focus arrangement) is considered, the rate of change is small compared to the change in K _a (Tables 6, 7 and 8 in the embodiment of Japanese Patent Application Laid-Open No. 5-142475, which was previously examined.

More specifically, the amount Δa of rotation for focusing in the ninth embodiment on the infinite object side becomes relatively smaller than that on the closest object side, compared with Japanese Patent Application Laid-Open No. 5-142475. In fact, if the ratio between the rotation amount for focusing under focusing on the closest distance and the rotation amount for focusing on the object distance (R = 5.0 m) is calculated from Tables 1 and 118, this is 3,379 / 10.0 = 0.338 in Embodiment of Japanese Patent Application Laid-Open No. 5-142475 as it becomes -0.914 / -8.5 = 0.108 in the 13th embodiment. As described above, when the focus cam is used with the arrangement of the present invention, since the amount Δa of a rotation for focusing becomes relatively smaller on the infinite object side, the conversion coefficient K _a becomes relatively large on the infinite object side and consequently, the change in the conversion coefficient K _a in the direction of rotation can be reduced compared to the conventional system.

The calculation results of the change rate of K _a with respect to γ _a at the infinite focus position and the closest focus position at the wide-angle end position, the center position and the telephoto end position in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 and in the 13th embodiment of the present invention are as follows.

Embodiment of Japanese Patent Application Laid-Open No. 5-142475

13th embodiment

As described above, according to the present invention, since the rate of change of K _a with respect to γ _{a is} small compared to the conventional system, the contribution of the correction term (ΔBf / µ) to K _a = γ _a (1- ΔBf / µ) can be further reduced, the value of the correction coefficient µ can be set to be large compared to the defocus amount ΔBf, and at the same time the change in the correction coefficient µ can be decreased.

Therefore, even if only a pair of a conversion coefficient value γ _a and a correction coefficient value µ are set for a given lens arrangement range, an error in the conversion coefficient K _a calculated using γ _a and µ or in the actual lens driving amount Δa for focusing can be eliminated.

Next, in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 and the 13th embodiment of the present invention, the lens driving amounts focusing from an infinite focus lens array to the closest object distance and focusing from the closest focus lens array to the infinite object distance at the wide-angle end position, the center position and the telephoto end position are calculated from Δa = ΔBf / γ _a (1 - ΔBf / µ), and errors from the actual lens drive amounts are then calculated to obtain the following values. It should be noted that the value of the correction coefficient µ while focusing from the infinite lens arrangement in focus to the closest object distance takes a value at the object distance (POS-5) and the value of the correction coefficient µ while focusing from the closest, lens arrangement in focus to the infinite object distance assumes a value at the object distance (POS-4).

Embodiment of Japanese Patent Application Laid-Open No. 5-142475

13th embodiment

As described above, even if only a pair of a conversion coefficient γ _a and a correction coefficient value µ are set for a given lens arrangement range, an error between the conversion coefficient K _a , which is made up of γ _a and µ and the lens driving amount Δa for focusing is calculated, small compared to the conventional system, and focusing can be realized with higher accuracy.

For purposes of reference, if there are errors in the lens drive amounts below Focus from the infinite, in-focus lens array to that Object distance (R = 10.0 m) and focusing from the closest one, in focus sensitive arrangement to the object distance (R = 1.0 m) is calculated and compared who get the following results. As seen from these tables that can, the focusing accuracy can be relatively independent of the object stand to be improved.

13th embodiment

Next, a check is made to see if not just an accurate auto focus will be carried out, but also a so-called manual focus tion in the zoom lens in the 13th embodiment can be achieved.

Table 126 summarizes the amount (ANGLE DA) of a rotation for focusing under one manual focusing using the focus cam (the middle table in Table 118) of the 13th embodiment, the amount X (mm) of a movement, namely in the direction of the optical axis of the focusing lens unit corresponding to the Amount of a rotation for focusing, and the shift amount Bf (mm) of the Ab education point when the amount (DX) of a movement in the direction of the optical Axis is given together.

The upper table in Table 126 summarizes the amount of shift Bf of a map points according to the photographing distances (R = 5.0, 3.0, 2.0, 1.5, 1.0 and 0.80 m) in the respective zooming states of the focus lengths (F = 28.7, 35.0, 50.0, 70.0, 105.0 and 1031.0 mm) together and the middle table summarizes the values of the amount (ANGLE DA) a rotation for focusing, which is used to achieve an opti paint, in the state in focus with regard to the respective photography stands (R = 5.0, 3.0, 2.0, 1.5, 1.0 and 0.80 m) is required. It should be noted that the rotation amounts to focus, the values to eliminate any ver shift of the imaging point at the wide-angle end position and the telephoto endpo sition are selected. The table below summarizes the amounts (DX) of a movement supply, in the direction of the optical axis, of the respective lens units  corresponding to the amount (ANGLE DA) of a rotation for focusing in association to the photographing distances (R = 5.0, 3.0, 2.0, 1.5, 1.0 and 0.80 m) in the respective States with the focus lengths (F = 28.7, 35.0, 50.0, 70.0, 105.0 and 131.0 mm) together. In the table below, (F) is the focus length (mm) of the entire system, (R) is the photographing distance (m) and (DX) is the amount (mm) of a movement in the Optical axis direction of each of the first, second, third, fourth and the fifth lens unit in order from the right side. It should be noted that the amount of movement in the direction of the optical axis toward the object side is represented by a positive value.

Table 126

Shift amount Bf (mm) of an imaging point and amount (DX) (mm) of a movement for focusing in the 13th embodiment

As can be seen from table 126, a so-called manual Focusing can be obtained because of the shift amounts of the imaging point the respective focus lengths and photographing distances is very small, and they fall into within the depth of focus regardless of the zooming state and the photographer distance.

[14. Embodiment]

The 14th embodiment is directed to a zoom lens having an arrangement with four units, ie a positive, a negative, a positive and a negative lens unit, and a focus by a negative, second lens unit, as in the embodiment Japanese Patent Application Laid-Open No. 5-142475, previously described in detail as prior art. In this zoom lens, the rotation amount ratio (a _F / a _Z ) of the rotation amount for focusing from the infinite position in focus to the closest position in focus (R = 0.5 m) becomes the amount of rotation Zooming from the wide-angle end position (F = 29.0) to the telephoto end position (F = 102.0) is set so that it is -0.95.

Table 127 below summarizes various paraxial data of an optical system and Data for determining the shape of a focus cam according to the 14th embodiment together.

The upper table in Table 127 summarizes the focus lengths and the symmetry point inter vall data of the respective lens units of the optical system corresponding to FIG. 14. Embodiment in association with six zooming states (focus lengths F = 29.0, 35.0, 50.0, 70.0, 85.0 and 102.0 mm) together.

The middle table in Table 127 summarizes the wedge scan data when the shape of the focus cam in the second lens unit of the 14th embodiment, which for Fo kissing is used, expressed by the wedge function given above is the angle of rotation of a rotatable lens barrel and the amount x is associated with movement in the direction of the optical axis.  

Furthermore, the lower table in table 127 summarizes the infinite positions in focus (positions corresponding to infinity) at the respective focus lengths (F = 29.0, 35.0, 50.0, 70.0, 85.0 and 102.0 mm) and the amounts of rotation (amounts of one rotation Focusing) focusing on the respective photographing distances (R = 5.0, 3.0, 2.0, 1.0, 0.7 and 0.5 m) using the focus cam of the 14th embodiment together. In this table, since the amount of rotation for zooming from the wide-angle end position (F = 29.0) to the telephoto end position (F = 102.0) is set to be 10.0, and the amount of rotation for focusing from the infinite is in Focus position to the closest position in focus (R = 0.5 m) is set to be -9.5, the rotation amount ratio (a _F / a _Z ) of the rotation amount for focusing to the amount of rotation to Zooming in the 14th embodiment -0.95.

Table 127

14th embodiment f = 29.0 to 102.0 (rotation amount ratio: a _F / a _Z = -0.95)

Focus lengths and symmetry point intervals of lens units of the 14th embodiment

Focus cam shape (wedge interpolation sampling point) according to the 14th embodiment

Amount of rotation for zooming and amount of rotation for focusing of the 14th embodiment

(Rotation amount ratio: a _F / a _Z = -0.95)

Table 128 below summarizes the numerical data values of the cams in the focus lens unit in the 14th embodiment, and this data by Interpolation based on a wedge function based on the scan data of the focus Nockens are calculated, which are summarized in the middle table in Table 127 are. It should be noted that the meaning of the respective reference symbols in Ta belle 128 are the same as those according to the 13th embodiment.

Table 128

Numerical cam data values of a focusing lens unit in the 14th embodiment

The left table in Table 128 summarizes the numerical data values of the focus cam the 14th embodiment together and the right table in Table 128 summarizes the nu merit data values of the zoom compensation cam of this embodiment together. A value obtained by synthesizing the amounts (2) of a movement in the Direction of the optical axis in the numerical data values of the focus cam and the zoom compensation cam in the range of the amount of rotation (ANGLE = 0.0) on the amount of a rotation (ANGLE = 10.0) is correct the movement point of the second lens unit, which using the Pa raxial data are calculated in the upper table in Table 127.

Tables 129, 130 and 131 below summarize the amount DX (mm) of a movement for focusing in the direction of the optical axis of the focusing lens unit, the magnification β _{x of} the respective lens units, the conversion coefficient γ _x , the direction of the optical Axis is assigned, the slope (dx / da) of the focus cam and the conversion coefficient γ _a , which corresponds to the direction of a rotation at the wide-angle end position (F = 29.0), the middle position (F = 50.0) and the telephoto end position (F = 102.0) is assigned, according to the 14th embodiment in each case together. The arrangements of the respective tables and the meaning of the symbols are the same as those in the 13th embodiment.

Table 129

Amount DX (mm) of a movement to focus in the direction of the optical axis at the wide-angle end position (29.0 mm) in the 14th embodiment

Image magnification β _{K of} the lens units at the wide-angle end position (29.0 mm) in the 14th embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the wide-angle end position (29.0 mm) in the 14th embodiment

Slope dx / da of the focus cam at the wide-angle end position (29.0 mm) in the 14th embodiment

Conversion coefficient γ _a , which is assigned to the direction of rotation at the wide-angle end position (29.0 mm) in the 14th embodiment

Table 130

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the center position (50.0 mm) in the 14th embodiment

Image magnification β _{K of} the lens units at the central position (50.0 mm) in the 14th embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the central position (50.0 mm) in the 14th embodiment

Slope dx / da of the focus cam at the middle position (50.0 mm) in the 14th embodiment

Conversion coefficient γ _a , which is assigned to the direction of rotation at the center position (50.0 mm) in the 14th embodiment

Table 131

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the telephoto end position (102.0 mm) in the 14th embodiment

Magnification β _{K of} the lens units at the telephoto end position (102.0 mm) in the 14th embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the telephoto end position (102.0 mm) in the 14th embodiment

Slope dx / da of the focus cam at the telephoto end position (102.0 mm) in the 14th embodiment

Conversion coefficient γ _a , which is assigned to the direction of rotation at the telephoto end position (102.0 mm) in the 14th embodiment

As can be seen from Tables 129, 130 and 131, the conversion coefficient γ _x , which is assigned to the direction of the optical axis, increases at each focus length, but the slope (dx / da) of the focus cam decreases when the Photography distance comes closer to the first distance. Therefore, as can be seen from these tables, the conversion coefficient γ _{a associated with} the direction of rotation, which is defined as the product of the conversion coefficient γ _x and the slope (dx / da) of the focus cam, decreases the photographing distance comes closer to the closest distance due to the influence of the slope (dx / da) of the focus cam. From Tables 129, 130 and 131, the rate of change from the infinite focus position to the closest focus position of the conversion coefficient γ _{a associated} with the direction of rotation is x0.48 at the wide-angle end position ( F = 29.0), x0.42 at the middle position (F = 50.0) and x0.32 at the telephoto end position (F = 102.0). When the number N of divisions of the focus area is calculated with a change in the conversion coefficient γ _a in the 14th embodiment using the formula (a) and that in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 is compared, the numbers N _W , N _M and N _{T of} the subdivisions at the wide-angle end position, the middle position and the telephoto end position each have the following values:
Embodiment of Japanese Patent Application Laid-Open No. 5-142475
N _W <9.3, N _M <10.1, N _T <8.1
14th embodiment
N _W <4.1, N _M <4.7, N _T <6.2.

Therefore, as can be seen from the comparison above, whether probably this embodiment has a larger zoom ratio than that in the embodiment form of Japanese Patent Application Laid-Open No. 5-142475 owns the Small numbers of divisions.

Also, as described above, in the 14th embodiment, since the rate of change of the conversion coefficient γ _{a assigned} to the direction of rotation is smaller than that in the conventional system, the values of the numbers N of the divisions become small. For this reason, the number of data of the conversion coefficient γ _a and the correction coefficient µ can be reduced and the storage capacity can be reduced.

Tables 132, 133 and 134 summarize the calculation results of the conversion coefficient K _a and the correction coefficient µ at the wide-angle end position (F = 29.0), the middle position (F = 50.0) and the telephoto end position (F = 102.0) according to the 14th embodiment. The arrangements of the tables and symbols are the same as those of the ninth embodiment. The position of the focusing lens in the first pair in the top two tables, in each of tables 132, 133 and 134, ie in the third and fourth columns, is (R, ANGLE) = (0.0, 0.0) and it indicates that this position corresponds to the infinitely corresponding position. Similarly, the position of the focusing lens in the fourth pair in the lower two tables in each of tables 132, 133 and 134, ie in the ninth and tenth columns, (R, ANGLE) = (0.5, -9.5), and it indicates that this position corresponds to the closest position in focus (R = 0.5 m) corresponding position.

Table 132

Conversion coefficient K _a : (rs), γ _a : (r) assigned to the direction of rotation, and correction coefficient µ: (l) at the wide-angle end position (29.0 mm) of the 14th embodiment

f = 29.0 mm

Table 133

Conversion coefficient K _a : (rs), γ _a : (r) assigned to the direction of rotation, and correction coefficient µ: (l) at the central position (50.0 mm) of the 14th embodiment

f = 50.0 mm

Table 134

Conversion coefficient K _a : (rs), γ _a : (r) assigned the direction of rotation and correction coefficient µ: (l) at the telephoto end position (102.0 mm) of the 14th embodiment

f = 102.0 mm

The calculation results of the change rate of K _a with respect to γ _a at the infinite focus position and the closest focus position at the wide-angle end position, the center position and the telephoto end position in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 and in the 14th embodiment of the present invention are as follows.

Embodiment of Japanese Patent Application Laid-Open No. 5-142475

14th embodiment

As described above, in the 14th embodiment, too, since the rate of change of K _a with respect to γ _{a is} small compared to the conventional system and the contribution of the correction term (ΔBf / µ) in K _a = γ _a (1 - ΔBf / µ), an error in the conversion coefficient K _a calculated using γ _a and µ be, or in the actual lens driving amount γ _a can be eliminated for focusing if only a pair of a conversion coefficient value γ _a and a correction coefficient value µ for a given lens array region (e.g., the infinite array region in focus).

Next, in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 and the 14th embodiment of the present invention, the lens drive amounts focusing from an infinite focus lens arrangement to the closest object distance and focusing from the closest focus lens arrangement to the infinite object distance at the wide-angle end position, the center position and the telephoto end position are calculated from Δa = ΔBf / γ _a (1 - ΔBf / µ), and errors from the actual lens drives are then calculated to obtain the following values. It should be noted that the value of the correction coefficient µ while focusing from the infinite lens arrangement in focus to the closest object distance takes a value at the object distance (POS-5) and the value of the correction coefficient µ while focusing from the closest, lens arrangement in focus to the infinite object distance assumes a value at the object distance (POS-4).

Embodiment of Japanese Patent Application Laid-Open No. 5-142475

14th embodiment

Also, as described above, in the 14th embodiment, even if only a pair of a conversion coefficient value γ _a and a correction coefficient value µ are set for a given lens arrangement range, an error between the conversion coefficient K _a which is made up of γ _a and µ and the lens drive amount Δa is calculated for focusing, small compared to the conventional system, and focusing can be realized with higher accuracy.

Table 135 summarizes the amount (ANGLE DA) of a rotation for focusing under one manual focusing using the focus cam (the middle table in Table 127) of the 14th embodiment, the amount X (mm) of a movement, namely in the direction of the optical axis of the focusing lens unit corresponding to the Amount of rotation for focusing, and the amount of displacement Bf (mm) of  Imaging point when the amount (DX) of movement in the direction of the optical Axis is given together.

It should be noted that the arrangement of the table and the symbols are the same as that are those in the 13th embodiment. The upper table in Table 135 summarizes the Ver shift amount Bf of an imaging point corresponding to the photographing distances (R = 5.0, 3.0, 2.0, 1.0, 0.7 and 0.5 m) in the respective zooming states of the Fo kus lengths (F = 29.0, 35.0, 50.0, 70.0, 85.0 and 102.0 mm) together and the middle The table summarizes the values of the amount (ANGLE DA) of a rotation for focusing together to achieve an optimal, in-focus state of the respective photographing distances are required. The table below summarizes the Amounts (DX) of a movement in the direction of the optical axis, the respective Lin units corresponding to the amount (ANGLE DA) of a rotation for focusing in Allocation to the respective focus lengths and photographing distances together.

Table 135

Displacement amount Bf (mm) of an imaging point and amount (DX) (mm) of a movement for focusing in the 14th embodiment

As can be seen from table 135, according to the zoom lens 14th embodiment, so-called manual focusing can be obtained because the amounts of displacement of the imaging point at the respective focus lengths and Photography distances are very small and they do not fall within the depth of focus depending on the zooming state and the photographing distance.

[15. Embodiment]

The 15th embodiment is directed to a zoom lens which has an arrangement with four units, ie a positive, a negative, a positive and a positive lens unit, and a focus by a negative, second lens unit, as in the embodiment Japanese Patent Application Laid-Open No. 5-142475, previously described in detail as prior art. In this zoom lens, the rotation amount ratio (a _F / a _Z ) of the rotation amount for focusing from the infinite position in focus to the closest position in focus (R = 0.5 m) becomes the amount of rotation Zooming from the wide-angle end position (F = 28.8) to the telephoto end position (F = 82.5) is set so that it is -0.9.

Table 136 below summarizes various paraxial data of an optical system and Data for determining the shape of a focus cam according to the 15th embodiment together. The upper table in Table 136 summarizes the focus lengths and symmetry point interval data of the respective lens units of the optical system  corresponding to the 15th embodiment in association with six zooming states (Focus lengths F = 28.8, 35.0, 50.0, 60.0, 70.0 and 82.5 mm) together.

The middle table in Table 136 summarizes the wedge scan data when the shape of the focus cam in the second lens unit of the 15th embodiment, which for Fo kissing is used, printed out by the wedge function given above is the angle of rotation of a rotatable lens barrel and the amount x is associated with movement in the direction of the optical axis.

Furthermore, the lower table in table 136 summarizes the infinite positions in focus (positions corresponding to infinity) at the respective focus lengths (F = 28.8, 35.0, 50.0, 60.0, 70.0 and 82.5 mm) and the amounts of rotation (amounts of one rotation Focusing) focusing on the respective photographing distances (R = 5.0, 3.0, 2.0,1.0, 0.7 and 0.5 m) using the focus cam of the 15th embodiment together. In this table, since the amount of rotation for zooming from the wide-angle end position (F = 28.8) to the telephoto end position (F = 82.5) is set to be 10.0, and the amount of rotation for focusing from the infinite is in Focus position to the closest position in focus (R = 0.5 m) is set to be -9.0, the rotation amount ratio (a _F / a _Z ) of the rotation amount for focusing to the amount of rotation to Zooming in the 15th embodiment -0.90.

Table 136

15th embodiment f = 28.8 to 82.5 (rotation amount ratio: a _F / a _Z = -0.90)

Focus lengths and symmetry point intervals of lens units of the 15th embodiment

Focus cam shape (wedge interpolation sampling point) according to the 15th embodiment

Amount of rotation for zooming and amount of rotation for focusing of the 15th embodiment

(Rotation amount ratio: a _F / a _Z = -0.90)

Table 137 below summarizes the numerical data values of the cams in the focus end lens unit in the 15th embodiment, this data by Interpolation based on a wedge function based on the scan data of the focus Nockens are calculated, which are summarized in the middle table in Table 136 are. It should be noted that the meaning of the respective reference symbols in Ta belle 137 are the same as those according to the 13th embodiment.

Table 137

Numerical cam data values of a focusing lens unit in the 15th embodiment

The left table in Table 137 summarizes the numerical data values of the focus cam the 15th embodiment together and the right table in Table 137 summarizes the nu merit data values of the zoom compensation cam of this embodiment together. A value obtained by synthesizing the amounts (2) of a movement in the Direction of the optical axis in the numerical data values of the focus cam and the zoom compensation cam in the range of the amount of rotation (ANGLE = 0.0) on the amount of a rotation (ANGLE = 10.0) is correct  the movement point of the second lens unit, which using the Pa raxial data in the upper table in Table 136 is calculated.

Tables 128, 139 and 140 below summarize the amount DX (mm) of a movement for focusing in the direction of the optical axis of the focusing lens unit, the magnification β _{x of} the respective lens units, the conversion coefficient γ _x , the direction of the optical Axis is assigned, the slope (dx / da) of the focus cam and the conversion coefficient γ _a , which corresponds to the direction of a rotation at the wide-angle end position (F = 28.8), the middle position (F = 50.0) and the telephoto end position (F = 82.5) is assigned, according to the 15th embodiment in each case together. The arrangements of the respective tables and the meaning of the reference symbols are the same as those in the 13th embodiment.

Table 138

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the wide-angle end position (28.8 mm) in the 15th embodiment

Image magnification β _{K of} the lens units at the wide-angle end position (28.8 mm) in the 15th embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the wide-angle end position (28.8 mm) in the 15th embodiment

Slope dx / da of the focus cam at the wide-angle end position (28.8 mm) in the 15th embodiment

Conversion coefficient γ _{a assigned} to the direction of rotation at the wide-angle end position (28.8 mm) in the 15th embodiment

Table 139

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the central position (50.0 mm) in the 15th embodiment

Magnification β _{K of} the lens units at the central position (50.0 mm) in the 15th embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the central position (50.0 mm) in the 15th embodiment

Slope dx / da of the focus cam at the middle position (50.0 mm) in the 15th embodiment

Conversion coefficient γ _a , which is assigned to the direction of rotation at the center position (50.0 mm) in the 15th embodiment

Table 140

Amount DX (mm) of a movement for focusing in the direction of the optical axis at the telephoto end position (82.5 mm) in the 15th embodiment

Image magnification β _{K of} the lens units at the telephoto end position (82.5 mm) in the 15th embodiment

Conversion coefficient γ _x , which is assigned to the direction of the optical axis at the telephoto end position (82.5 mm) in the 15th embodiment

Slope dx / da of the focus cam at the telephoto end position (82.5 mm) in the 15th embodiment

Conversion coefficient γ _a , which is assigned to the direction of rotation at the telephoto end position (82.5 mm) in the 15th embodiment

As can be seen from Tables 138, 139 and 140, the conversion coefficient γ _x , which is assigned to the direction of the optical axis, increases at each focus length, but the slope (dx / da) of the focus cam decreases when the Photography distance comes closer to the first distance. Therefore, as can be seen from these tables, the conversion coefficient γ _{a associated with} the direction of rotation, which is defined as the product of the conversion coefficient γ _x and the slope (dx / da) of the focus cam, decreases the photographing distance comes closer to the closest distance due to the influence of the slope (dx / da) of the focus cam. From Tables 138, 139 and 140, the rate of change from the infinite, in-focus position to the closest, in-focus position of the conversion coefficient γ _a , which is assigned to the direction of rotation, is x0.49 at the wide-angle end position ( F = 28.8), x0.44 at the middle position (F = 50.0) and x0.35 at the telephoto end position (F = 82.5). When the number N of divisions of the focus area is calculated with a change in the conversion coefficient γ _a in the 15th embodiment using the formula (a) and that in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 is compared, the numbers N _W , N _M and N _{T of} the subdivisions at the wide-angle end position, the middle position and the telephoto end position each have the following values:
Embodiment of Japanese Patent Application Laid-Open No. 5-142475
N _W <9.3, N _M <10.1, N _T <8.1
15th embodiment
N _W <3.9, N _M <4.5, N _T <5.8.

Also, as described above, in the 15th embodiment, since the rate of change of the conversion coefficient γ _{a assigned} to the direction of rotation is smaller than that in the conventional system, the values of the numbers N of the divisions become small. For this reason, the number of data of the conversion coefficient γ _a and the correction coefficient µ can be reduced and the storage capacity can be reduced.

Tables 141, 142 and 143 summarize the calculation results of the conversion coefficient K _a and the correction coefficient µ at the wide-angle end position (F = 28.8), the middle position (F = 50.0) and the telephoto end position (F = 82.5) according to the 15th embodiment. The arrangements of the tables and reference symbols are the same as those of the ninth embodiment. The position of the focusing lens in the first pair in the top two tables, in each of tables 141, 142 and 143, ie in the third and fourth columns, is (R, ANGLE) = (0.0, 0.0) and indicates that this position corresponds to the infinitely corresponding position. Similarly, the position of the focusing lens in the fourth pair in the lower two tables in each of Tables 141, 142 and 143, ie, in the ninth and 10th columns, (R, ANGLE) = (0.5, -9.50), and shows indicates that this position corresponds to the closest position in focus (R = 0.5 m) corresponding position.

Table 141

Conversion coefficient K _a : (rs), γ _a : (r) assigned to the direction of rotation, and correction coefficient µ: (l) at the wide-angle end position (28.8 mm) of the 15th embodiment

f = 28.8 mm

Table 142

Conversion coefficient K _a : (rs), γ _a : (r) assigned to the direction of rotation, and correction coefficient µ: (l) at the central position (50.0 mm) of the 15th embodiment

f = 50.0 mm

Table 143

Conversion coefficient K _a : (rs), γ _a : (r) assigned the direction of rotation and correction coefficient µ: (l) at the telephoto end position (82.5 mm) of the 15th embodiment

f = 82.5 mm

The calculation results of the rate of change of K _a with respect to γ _a at the infinite, in-focus arrangement and the closest, in-focus arrangement at the wide-angle end position, the middle position and the telephoto end position in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 and in the 14th embodiment of the present invention are as follows.

Embodiment of Japanese Patent Application Laid-Open No. 5-142475

15th embodiment

Also, as described above, in the 15th embodiment, since the rate of change of K _a with respect to γ _{a is} small compared to the conventional system, the contribution of the correction term (ΔBf / µ) in K _a = γ _a (1st - ΔBf / µ) can be reduced. For this reason, an error in the conversion coefficient K _a calculated using γ _a and µ or an error in the actual lens driving amount γ _a obtained when only a pair of a conversion coefficient value γ _a and a correction coefficient value µ is specified, reduced.

Next, in the embodiment of Japanese Patent Application Laid-Open No. 5-142475 and the 15th embodiment of the present invention, the lens drive amounts focusing from an infinite, in-focus lens array to the closest object distance and focusing from the closest. the lens arrangement in focus to the infinite object distance under the wide-angle end position, the middle position and the telephoto end position is calculated from Δa = ΔBf / γ _a (1 - ΔBf / μ), and errors from the actual lens drive amounts are then calculated, the following Values are obtained. Note that the value of the correction coefficient µ while focusing from the infinite lens array in focus to the closest object distance takes a value at the object distance (POS-5), and the value of the correction coefficient µ while focusing from the closest one lens arrangement in focus to the infinite object distance assumes a value at the object distance (POS-4).

Embodiment of Japanese Patent Application Laid-Open No. 5-142475

15th embodiment

Also, as described above, in the 15th embodiment, even if only a pair of a conversion coefficient value γ _a and a correction coefficient value µ are set for a given lens arrangement range, an error between the conversion coefficient K _a made from γ _a and µ and the lens drive amount Δa is calculated for focusing, small compared to the conventional system, and focusing can be realized with higher accuracy.

Table 144 summarizes the amount (ANGLE DA) of a rotation for focusing under one manual focusing using the focus cam (the middle table in Table 136) of the 15th embodiment, the amount X (mm) of a movement, namely in the direction of the optical axis of the focusing lens unit corresponding to the Amount of a rotation for focusing, and the shift amount Bf (mm) of the Ab education point when the amount (DX) of a movement in the direction of the optical Axis is given together.

It should be noted that the arrangement of the table and the reference symbols are the same are like those in the 13th embodiment. The upper table in Table 144 summarizes the shift amount Bf of an imaging point according to the photographers distances (R = 5.0, 3.0, 2.0, 1.0, 0.7 and 0.5 m) in the respective zooming states the focus lengths (F = 28.8, 35.0, 50.0, 60.0, 70.0 and 82.5 mm) together and the mean The table below summarizes the values of the amount (ANGLE DA) of a rotation for focusing together, to achieve an optimal, in-focus state of the respective photographing distances are required. The table below summarizes the  Amounts (DX) of a movement in the direction of the optical axis, the respective Lin units corresponding to the amount (ANGLE DA) of a rotation for focusing in Allocation to the respective focus lengths and photographing distances together.

Table 144

Shift amount Bf (mm) of an imaging point and amount (DX) (mm) of a movement for focusing in the 15th embodiment

As can be seen from table 144, according to the zoom lens the 15th embodiment, a so-called manual focus can be obtained because the amounts of displacement of the imaging point at the respective focus lengths and Photography distances are very small and they do not fall within the depth of focus depending on the zooming state and the photographing distance.

As described above with reference to the embodiments, the present Invention in zoom lens systems based on various lens units arrangements or focusing lens units are applied.  

As described above, according to the present invention, in an inner focusing type zoom lens, e.g. B. is attached to an auto-focusing camera, which has a focus determining device, a storage device, egg ne computing device, and the like, the number of data of specific coefficients (z. B. the conversion coefficient γ _a and the correction coefficient µ), which for Auto-focusing are required, compared to the conventional system. Furthermore, an error by calculating the lens driving amount of the focusing lens unit using the stored specific coefficients corresponding to the determined defocusing amount can be reduced compared to the conventional system.

In other words, when the arrangement of the present invention is adapted, since the rate of change of the conversion coefficient γ _{a is} reduced compared to the conventional system, the number of data of the conversion coefficient γ _a , the correction coefficient µ and the like, which is used to calculate the lens drive amount stored for focusing, can be reduced and a cost reduction can be realized in terms of the storage capacity.

Furthermore, since the change in the conversion coefficient K _a to the conversion coefficient γ _a becomes small, the contribution of the correction term (ΔBf / µ) to K _a = γ _a (1 - ΔBf / µ) can be reduced.

Therefore, an error of the conversion coefficient K _a calculated based on γ _a and µ, or an error from the actual lens driving amount Δa obtained when only a pair of a conversion coefficient value γ _a and a correction coefficient value µ for a given lens arrangement range be set up, reduced.

In the present invention, the conversion coefficient γ _a at a focus point and the conversion coefficient µ defined by the formula K _a = γ _a (1 - ΔBf / µ) are set to be specific coefficients. Alternatively, a correction coefficient defined by a formula different from the above formula can be set. Furthermore, the conversion coefficient γ _a need not always be determined in accordance with the sensitivity (dBf / da) which is assigned to the direction of rotation at the point in focus. As long as focusing accuracy can be improved, the sensitivity of a point other than that of the point in focus and the corresponding correction coefficient can be set to be specific coefficients.

It should be noted that the present invention is applicable to various other zoom Lens systems based on lens unit arrangements or focusing Lin units that are not those in the previous he are mentioned embodiments, as is self-evident.

Claims (8)

1. Zoom lens system in which a moving point of a focusing lens unit by synthesizing a focus cam and a zoom compensation cam specifying a predetermined moving point for zooming by a movement amount in a direction of an optical axis of lens units and a rotation angle of a rotatable lens barrel, wherein a ratio (dBf / dx) of an amount dBf of an infinitesimal movement of an imaging plane to an amount dx of an infinitesimal movement in the direction of the optical axis of the focusing lens unit and a ratio (dBf / da) of the amount dBf one infinitesimal movement of the imaging plane to an amount since an infinitesimal movement in a rotational direction of the focusing lens unit on the focus cam is represented by γ _xO and γ _aO at an infinite point in focus and by γ _xR and γ _{aR, respectively} closest to yourself point in focus are shown, the zoom lens fulfilling the following state formula at least at the telephoto end position: 1.0 <γ _xR / γ _xO and if a ratio of an amount a _{F of} a rotation of the focusing lens unit on the focus cam, the Amount of focusing from an infinite, in-focus state to a closest, in-focus state corresponds to an amount a _z of rotation corresponding to zooming from a wide-angle end position to the telephoto end position so that it meets: - 1.0 <a _F / a _Z <-0.7 then the zoom lens fulfills the following state formula at least at the wide-angle end position and the telephoto end position: 0.3 <γ _aR / γ _aO <0.7 2. Zoom lens according to claim 1, wherein when conversion coefficients K _a , which are expressed by K _a = ΔBf / Δa and are obtained when the focusing lens unit in lens arrangements corresponding to the infinite, in-focus state and the closest state in focus is arranged, each represented by K _aO and K _aR , the zoom lens fulfills the following state formulas at least at the wide-angle end position and the telephoto end position: 0.6 <K _aO / γ _aO <1.2
0.8 <K _aR / γ _aR <1.7 where
ΔBf = the defocus amount between an imaging position of an object at an arbitrary position and a predetermined imaging point position,
Δa = the angle of rotation of the focusing lens unit on the focus cam, which is required to achieve a state of an object in focus. 3. Zoom lens system in which a moving point of a focusing lens unit is defined by synthesizing a focus cam and a zoom compensation cam so as to maintain a state in focus by a substantially constant amount of rotation for an identical one Obtain the object distance irrespective of a zooming state by specifying a predetermined movement point for zooming by an amount of movement in a direction of an optical axis of the lens units and an angle of rotation of a rotatable lens drum, and if the ratios (dBf / dx) of an amount dBf of an infinitesimal movement of an imaging plane to an amount dx of an infinitesimal movement in the direction of the optical axis of the focusing lens unit at an infinite and a closest point in focus are represented by γ _xO and γ _xR, respectively, amounts one Movement in the direction of optical axis of the focussing lens unit, which are represented by Δx _WR and Δx _TR for focusing an infinite position to a position of a closest distance at a wide-angle end position and a telephoto end position, and a rotation amount of the focusing lens unit on the focus cam, one Zooming from the wide-angle end position to the telephoto end position, and an amount of rotation corresponding to focusing from an infinite state in focus corresponding to a closest state in focus by a _Z and a _F , respectively, the zoom -Objectively the following state formulas are met at least at the telephoto end position: 1.00 <γ _xR / γ _xO <1.80
3.20 <Δx _TR / Δx _WR <4.50
-0.90 <a _F / a _Z <-0.70 4. The zoom lens system according to claim 3, wherein when the ratios (dBf / da) of the amount dBf of an infinitesimal movement of the imaging plane to an amount da of an infinitesimal movement in a rotation direction of the focusing lens unit on the focus cam the infinite and the closest point in focus are represented by γ _aO and γ _aR , the zoom lens fulfills the following state formula at least at the wide-angle end position and the telephoto end position: 0.25 <γ _aR / γ _aO <0.70 5. The zoom lens system according to claim 3, wherein when conversion coefficients K _a are expressed by K _a = ΔBf / Δa and are obtained when the focusing lens unit in lens arrays corresponding to the infinite state in focus and the closest state in focus are arranged, each represented by K _aO and K _aR , the zoom lens fulfills the following state formulas at least at the wide-angle end position and the telephoto end position: 0.60 <K _aO / γ _aO <1.20
0.80 <K _aR / γ _aR <1.70 where
ΔBf = the defocus amount between an imaging position of an object at an arbitrary position and a predetermined imaging point position,
Δa = the angle of rotation of the focusing lens unit on the focus cam, which is required to achieve a state of an object in focus. 6. Zoom lens system in which a moving point of a focusing lens unit is defined by synthesizing a focus cam and a zoom compensation cam so as to be in a state in focus by a substantially constant amount of rotation for an identical object to obtain the object distance regardless of a zooming state by specifying a predetermined movement point for zooming by an amount of movement in a direction of an optical axis of the lens units and a rotation angle of a rotatable lens drum, when the ratios (dBf / dx) are one Amount dBf of an infinitesimal movement of an imaging plane to an amount dx of an infinitesimal movement in the direction of the optical axis of the focusing lens unit at an infinite and a closest point in focus are each represented by γ _xO and γ _xR , amounts of a movement in the direction of the opt axis of the focusing lens unit, which is represented by Δx _WR and Δx _TR for focusing an infinite position to a closest distance position and a telephoto end position, and an amount of rotation of the focusing lens unit on the focus cam, the egg nem Zooming from the wide-angle end position to the telephoto end position, and an amount of rotation corresponding to focusing from an infinite state in focus corresponding to a closest state in focus respectively represented by a _Z and a _F , the zoom Objectively, the following state formulas are met at least at the telephoto end position: 1.00 <γ _xR / γ _xO <1.80
2.00 <Δx _TR / Δx _WR <3.20
-1.00 <a _F / a _Z <-0.80 The zoom lens system according to claim 6, wherein when the ratios (dBf / da) of the amount dBf of an infinitesimal movement of the imaging plane to an amount da of an infinitesimal movement in a rotational direction of the focusing lens unit on the focus cam the infinite and the closest point in focus are represented by γ _aO and γ _aR , the zoom lens fulfills the following state formula at least at the wide-angle end position and the telephoto end position: 0.25 <γ _aR / γ _aO <0.70 8. The zoom lens system according to claim 6, wherein when conversion coefficients K _a are expressed by K _a = ΔBf / Δa and are obtained when the focusing lens unit in lens arrays corresponding to the infinite state in focus and the closest state in focus are arranged, each represented by K _aO and K _aR , the zoom lens fulfills the following state formulas at least at the wide-angle end position and the telephoto end position: 0.60 <K _aO / γ _aO <1.20
0.80 <K _aR / γ _aR <1.70 where
ΔBf = the amount of defocus between an imaging position of an object at an arbitrary position and a predetermined imaging point position
Δa = the angle of rotation of the focusing lens unit on the focus cam, which is required to achieve a state of an object in focus.