JP2718216B2 - Zoom lens system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a zoom lens, particularly to a focusing system thereof, from a so-called inner focus or rear focus system by moving a part of lens groups in a lens system. The present invention relates to any focusing method including a front lens feeding method by moving an object-side lens group and an entire feeding method in which the entire lens is moved.

[Conventional technology]

As a focusing method of the zoom lens, a so-called front lens feeding method of moving a lens group closest to the object side, an inner focusing method of moving a part of lens groups in a lens system,
There are a focus system and an entire extension system for focusing by the entire lens system. In general, the inner focus system, the rear focus system, and the whole extension system have a problem that the amount of extension required for the same photographing distance varies with the change of the focal length of the entire system.
For this reason, even if focusing is performed at an arbitrary focal length, ie, a focusing distance, if the magnification is changed and the focal length is changed, the imaging position greatly changes, and it is necessary to refocus each time. is there.

There have been proposed various methods of automatically processing this operation electrically. This method can be used as an autofocus method, but the distance adjustment ring (focusing ring) is manually operated to perform focusing. The so-called manual focus method cannot be dealt with at all.

Further, even when the method is limited to the auto-focusing method, it takes time to frequently calculate a feeding amount necessary for focusing according to a zoom state, which causes a problem in responsiveness as auto-focusing. Even in the front lens feeding method, in a zoom lens system in which the overall length changes, when the shooting distance is short, the difference in the feeding amount depending on the focal position increases, and thus the same problem as described above occurs.

As a method for solving the above problems, the lateral magnification of the focusing lens group is changed with magnification so that the amount of extension of the focusing lens group is substantially constant regardless of the focal length. There are those that have been configured. An example of this is disclosed in
As disclosed in JP-A-202416, a zoom lens that enables focusing by moving the three focusing lens groups integrally and by almost the same amount at any focal length independently of zooming is disclosed. Are known.

On the other hand, as disclosed in JP-A-57-4018 as a completely different method, by providing a new cam for focusing such that the variable power mechanism and the focusing mechanism are interlocked, the focal length is increased. There has been proposed a configuration in which focusing can be performed structurally even if the amount of feeding changes in accordance with the change in the distance.

[Problems to be solved by the present invention]

As described above, in the method in which the amount of focusing is made substantially constant irrespective of a change in the focal length, that is, a change in the zooming state, a plurality of lens groups move integrally for focusing. Therefore, it is not possible to adopt a floating mechanism that suppresses short-range aberration fluctuations, that is, to change the relative air gap between focusing lens groups during focusing, and it is not possible to obtain high performance during short-range focusing It is.

On the other hand, as shown in FIG. 25, a method of providing a new cam for focusing such that the variable power mechanism and the focusing mechanism are linked to each other is performed by setting the extension amount ΔX of the focusing group to the reciprocal of the focal length 1 / Curves obtained as intersections of a curved surface expressed as a variable of F and the shooting distance R and planes corresponding to various values of R parallel to the 1 / F-ΔX plane are respectively translated in the F-axis direction. This is used as a focusing cam instead of a single curve.

In this method, it is possible to focus even if the amount of extension of the focusing lens group varies depending on the focal length. However, in terms of the characteristic that the curves corresponding to various values of R are translated and replaced with one curve,
This cannot be realized if the change in the feeding amount due to the focal length does not change monotonically.

Furthermore, if floating is adopted for the focusing lens group to suppress short-range aberration fluctuation, the amount of parallel movement at the stage of obtaining the focusing curve from each curved surface differs, and the focusing cam of each group may correspond. Will be gone. Further, since it is conceivable that the amount of extension due to floating does not change monotonically due to aberration, there is a disadvantage that a focusing cam cannot be realized in each focusing group.

Therefore, an object of the present invention is to provide a simple configuration in which the amount of movement of a member that moves for focusing is maintained substantially constant regardless of a change in focal length, that is, a change in a zooming state.
The amount of movement of the focusing lens group itself during focusing can be changed to the optimum amount according to the zooming state, and at the time of short-distance focusing, the lens system has the maximum degree of freedom and high performance It is to provide a zoom lens system that can be obtained.

[Means for solving the problem]

The present invention relates to a zoom lens system having a lens group having both functions of zooming and focusing, and a zooming guide groove corresponding to a movement locus for zooming of a lens group having both functions of zooming and focusing. A first lens barrel member having a (zoom cam); and a focusing guide groove (focus cam) for moving a lens group having both functions of zooming and focusing for focusing along the optical axis. A second lens barrel member.

Here, the first lens barrel member and the second lens barrel member are relatively rotated about the optical axis of the zoom lens system as a rotation center, and a lens group having both functions of zooming and focusing is used for zooming. A desired zooming is performed by moving on the optical axis by an amount determined by the amount of displacement of the intersection between the guide groove (zoom cam) and the focusing guide groove (focus), and the first barrel member and the second The lens group having both functions of zooming and focusing by relatively moving the lens barrel member in the direction of the optical axis is used to move the lens group having the functions of the magnification guide groove (zoom cam) and the focusing guide groove (focus cam). By moving the optical axis on the optical axis by an amount determined by the displacement of the intersection of the two, focusing on a desired object is performed. Then, while maintaining a relative movement amount in the optical axis direction between the first lens barrel member and the second lens barrel member necessary for focusing on a predetermined object, regardless of the zoom state, The focusing guide groove is positioned with respect to the optical axis so that the amount of movement of the lens group having both functions of zooming and focusing on the optical axis for focusing can be changed according to the zooming state. It is formed in a non-linear shape having an inclined region.

[Action]

According to the configuration of the present invention, only two members, the first lens barrel member having the zooming guide groove (zoom cam) and the second lens barrel member having the focusing guide groove (focus cam), are provided. In this manner, zooming and focusing become possible, and in any zooming state, the first lens barrel member and the second lens barrel necessary for focusing from an infinity shooting state to a constant object distance are set.
The amount of relative movement in the optical axis direction with the lens barrel member can be made substantially constant.

That is, in a conventional general zoom lens, a zooming guide groove formed in a rotary lens barrel for defining a zooming movement locus of a zooming lens group, and movement of the lens group are regulated in the optical axis direction. The guide groove parallel to the optical axis is a non-linear movement trajectory that is variable-converted in the direction perpendicular to the optical axis direction, so that the amount of extension of the focusing lens group itself changes due to the change in the zooming state. However, even if a floating mechanism is assumed in order to suppress short-range aberration fluctuation, focusing can be performed by moving the focusing lens group itself along a movement locus that moves during zooming. Therefore, it is possible to cope with a so-called manual focus method, and it is also possible to increase the focusing speed at the time of autofocus.

Specifically, first, when expressing the movement trajectory moving for zooming as a variable in the optical axis direction and the rotation angle θ of the so-called rotating lens barrel orthogonal to the optical axis direction, the sum is obtained in an arbitrary zooming state. The amount of movement Δ of the focusing lens group that moves in the optical axis direction due to focusing
When X is converted into the rotation amount φ of the rotary barrel in the movement trajectory, a guide groove, which was conventionally a straight line parallel to the optical axis, forms an angle with the optical axis so that ΔX and φ are variables. Non-linear curved focusing guide groove (focus cam)
Convert to

At the same time, in order to correspond to the relationship between the movement trajectory of the focusing lens group during zooming and the linear trajectory of the guide groove before conversion, the movement trajectory for zooming of the focusing lens group based on the converted focus cam That is, the variable magnification guide groove (zoom cam) is changed in the direction of the rotation angle θ of the rotary lens barrel. By such a conversion operation, the guide groove for zooming (zoom cam) and the guide groove for focusing (focus cam) are determined.

As a result of these conversions, at the time of focusing, focusing becomes possible by moving the focusing lens group along a movement locus (zoom cam) that moves during zooming. During zooming, the converted focus cam and zoom cam are relatively rotated about the optical axis, that is, one of the converted focus cam and zoom cam is rotated in the θ direction orthogonal to the optical axis. In this case, the position on the optical axis of the lens group having the zooming function is changed to perform zooming. At the time of focusing, even if the amount of movement of each lens group in the optical axis direction differs with respect to an object at the same photographing distance, the converted focus cam is moved by substantially the same amount of movement ΔF in the optical axis direction. Is achieved. At this time, in order to employ so-called floating for correcting short-range aberration fluctuation due to relative movement of the focusing lens group at the time of focusing, the moving amount at the time of focusing is further changed for each focusing lens group. Movement of the focus cam in the optical axis direction
Focusing is possible by moving by F.

〔Example〕

Hereinafter, the present invention will be described in more detail based on examples.

As shown in FIG. 1, the zoom lens of Example 1 includes, in order from the object side, a first lens group G _{1 having} a positive refractive power, a second lens group G _{2 having} a negative refractive power, and a third lens having a positive refractive power. consists of four lens groups of the group G _3, and positive refractive power a fourth lens group G ₄ of moves toward the object side total lens group upon zooming from the wide-angle side to the telephoto side along the optical axis, No focus the time is a configuration in which the third lens group G ₃ and the fourth lens group G ₄ is moved along the optical axis.

To describe the configuration of each lens group, the first lens group G ₁ having a positive refractive power in order from the object side, positive having a strong surface curvature by the negative meniscus lens L ₁ and the object side with a convex surface on the object side consists lens L _2, the second lens group G ₂ having a negative refractive power of the negative lens L ₃ having a strong surface curvature the image side, a biconcave negative lens L _4, positive towards the surface with a stronger curvature the object side Lens L ₅
It is joined to a more a negative lens L ₆ having a strong surface curvature by the image side and the third lens group G ₃ having a positive refractive power is a positive lens L _7, which is a cemented positive lens L ₈ and therewith and a negative lens L ₉ Prefecture, the fourth lens group G ₄ having a positive refractive power is composed of a positive lens L ₁₀ having a strong surface curvature the object side double concave negative lens L ₁₁ Prefecture.

Table 1 shows the specifications of the zoom lens. f represents the focal length, and FN represents the F number. In the upper part of Table 1, r
Denotes a radius of curvature of each lens surface, d denotes a lens surface interval, n denotes a refractive index of each lens, V denotes an Abbe number, and a subscript denotes an order from the object side. The middle row of Table 1 shows the final lens L
The values of each coefficient representing the shape of the aspherical surface formed on the _eleventh object-side lens surface (r20) are shown.

The height of the aspheric surface from the optical axis is h, the distance of the vertex of the aspheric surface at h from the tangent plane is x, the conic constant is k,
The second, fourth, sixth, eighth, and tenth order aspherical coefficients are A ₂ , A ₄ , A ₆ , A ₈ , and A ₁₀ , respectively, and the paraxial radius of curvature is r. Then, it is expressed by the following aspherical equation.

In the middle part of the specification table of the lens system in Table 1, in order from the left, the conical constant k, the second order, the fourth order, the sixth order, the eighth order, and the
The values of the aspherical coefficients A ₂ , A ₄ , A ₆ , A ₂ , and A ₁₀ in FIG. ₁₀ are sequentially described. Note that En at the value of the aspheric coefficient is 10
^-n is shown. The lower part of Table 1 shows six positions (f = 3) corresponding to six zooming states from the wide-angle end to the telephoto end.
6.0, 50.0, 60.0, 70.0, 85.0, and 102.0).

FIG. 1 also shows the movement locus of each lens unit during zooming. Here Aru choose vertical axis (theta-direction) and the horizontal axis (optical axis direction) such that the straight line forms an angle of 45 ° moving track with respect to the optical axis during zooming of the first lens group G _1.

In this zoom lens, the third lens group G _{3 is used} to suppress short-range aberration fluctuation at a shooting distance of 1 m and maintain high imaging performance.
A movement amount ΔX in the optical axis direction for focusing while performing so-called floating plants out with the fourth lens group G ₄ If this value Δ
Table 2 shows each value of the value φ obtained by converting X into the rotation direction θ about the optical axis in the movement locus shown in FIG. Table 2
In the above, F indicates the focal length of the entire system, and (1) to (4)
Represents a first lens group G ₁ ~ fourth lens group G _4, R represents an object distance.

As shown in Table 2, and the third lens group G ₃ in the time of focusing only the fourth lens group G ₄ is moved along the optical axis, a first lens group G ₁ and the second lens group G ₂ fixed Have been.

Next, a method of transforming a moving trajectory including a guide groove parallel to the optical axis into variables in the θ direction using ΔX and φ as variables will be described. The converted focus cam and zoom cam are actually determined by three variables: the converted value φ, the ΔX before conversion, and the new value ΔF.

The value of the relative movement amount ΔF for focusing in the optical axis direction between the focus cam and the zoom cam introduced here is:
It is a constant value for the same shooting distance regardless of the zooming state, and defines the amount of movement of the focusing lens group that moves for focusing during focusing. In other words, even if the amount of movement of each focusing lens unit is different during focusing and the zooming state is different, the focus cam and the zoom cam are relatively moved in the optical axis direction by the same value ΔF. Focusing becomes possible.

FIG. 2 shows the focus cams CF1, CF2, CF3, CF4 and the zoom cams CZ1, CZ2, CZ3 obtained by converting the movement trajectory according to the present invention for the zoom lens according to the first embodiment shown in FIG. 1 and Table 1. , CZ4 is a diagram showing an outline of the shape, here, in order to show a comparison with the movement locus before conversion, the movement locus of each lens group in the conventional method before conversion below the figure
C1, C2, C3 and C4 are shown in comparison.

3A and 3B show the movement trajectory before the conversion, the rotation angle φ of the rotating lens barrel, the movement amount ΔX of the lens group moving for focusing on the optical axis, the focus cam and the zoom cam. FIG. 8 is a diagram showing that variable conversion is performed using the relative movement amount ΔF in the optical axis direction as a variable.

An operation for obtaining the converted focus cam and zoom cam as shown in FIG. 2 will be described with reference to FIGS. 3A and 3B. The movement locus before conversion is, as shown in the figure, a locus before conversion corresponding to a zooming guide groove formed in a rotary lens barrel for defining a zooming movement locus of the zooming lens group, and a lens. It comprises a guide groove parallel to the optical axis for restricting the movement of the group in the optical axis direction.

The relationship between the variables before and after the conversion is generally the moving direction at the time of zooming of the focusing lens group, the moving direction at the time of focusing, Δ
The value varies depending on various factors such as the method of selecting the sign of F and the magnitude relationship between ΔF and ΔX.
FIG. 3 is a diagram illustrating a relationship between the movement trajectory of the figure and the amount of movement shown in Table 2. In other words, the variable power lens group having the focusing function moves to the object side according to the zooming from the wide angle to the telephoto, and moves from the telephoto side to the wide angle side on the movement locus for the zooming to move to the image side during focusing. FIG. 11 is a conversion relation diagram when ΔF has the same sign as ΔX. 3A and 3B according to the magnitude relationship between ΔF and ΔX. In the drawing, the dashed line indicated as “trajectory before conversion” is a value φ obtained by converting the amount of movement in the optical axis direction required for focusing by the zooming / focusing lens group in the θ direction in an arbitrary zoom state. It is a movement locus at the time of zooming of the corresponding zooming and focusing lens group before conversion. Also,
A chain line shown as a “guide groove” is a linear trajectory parallel to the optical axis in the lens barrel structure. When these two trajectories are converted under the relationship of φ, ΔX, and ΔF shown in the figure, the trajectories of the focus cam and the zoom cam are obtained as shown by the solid lines in the figure.

Here, the correspondence between zooming and focusing before and after conversion will be described.

It is assumed that the position of the zooming and focusing lens group at an infinity shooting distance is in a position indicated by a point 0 in a certain zooming state. From this state, when the guide groove is translated by φ in the vertical axis direction (the rotation angle θ direction of the rotary lens barrel) for zooming, the trajectory before conversion and the guide groove intersect at the point A, and the zooming and focusing lens group is moved. In the optical axis direction, it moves from point O by an amount ΔX corresponding to point C.

Similarly, if the converted focus cam is also moved by φ in the vertical axis direction for zooming, the focus cam intersects with the zoom cam at the point B, and the zooming and focusing lens group is the same as before conversion in the optical axis direction. Then, the point O moves from the point O by an amount ΔX corresponding to the point C. Therefore, during zooming, the positional relationship in the optical axis direction is maintained before and after conversion.

On the other hand, at the time of focusing, if the converted focus cam is moved by ΔF in the optical axis direction, it intersects with the zoom cam at the point B, and the variable magnification and focusing lens unit moves in the optical axis direction by an amount ΔX corresponding to the point O to the point C. And the amount of movement required for focusing before conversion is equal to the amount of movement.

Therefore, by performing the conversion based on the relationships shown in FIGS. 3A and 3B, the correspondence between the scaling and the focusing is satisfied before and after the conversion.

In the description of FIGS. 3A and 3B, the same value ΔX is used as the movement amount at the time of zooming and the movement amount at the time of focusing. However, this is merely for convenience of explanation, and the movement amount of both is generally Have different values.

The conversion operation as described above is a case in which a desired short-distance focusing is performed based on the position of the zooming and focusing lens group at an infinity shooting distance in a certain zooming state. By similarly converting the movement locus before the conversion, the locus of the focus cam and the locus of the zoom cam can be determined. By executing the conversion of the movement trajectory over the entire zoom range in this manner, the final focus cam and zoom cam are determined as shown in FIG. Here, the focus cam is inclined with respect to the optical axis by sequentially performing the conversion operation as shown in FIG. 3A and FIG. Is formed in a non-linear shape having a region defined as above.

In the first embodiment, the focus cam and the zoom cam required for focusing on an object having an object distance of R = 1000 mm (1 m) for the third lens group G ₃ and the fourth lens group G ₄ as the variable power and focusing lens groups. Relative displacement ΔF in the optical axis direction with respect to
Is set to ΔF = −2.4 mm, ΔX, φ in Table 2
FIG. 2 shows the state of the final movement trajectory determined from. In FIG. 2, the relationship between the conversion of the focus cams CF1, CF2, CF3, CF4 and the zoom cams CZ1, CZ2, CZ3, CZ4 for giving the movement locus of each lens unit is based on the zooming state at the wide-angle end (W). And focus cam CF1, CF2, CF3, CF4 and zoom cam CZ for zooming to the telephoto end (T).
The relative movement of 1, CZ2, CZ3, and CZ4 in the direction perpendicular to the optical axis (vertical direction in FIG. 2) causes each lens group to move on the optical axis in accordance with the movement of the intersection of the two cams. Doubled. As shown, the movement locus of the first lens group G ₁ and the second lens group G ₂ is a zooming-only group that does not have a focusing function, movement trajectory even those in the structure of the present invention is the same as before the conversion The focus cams CF1 and CF2 are guide grooves parallel to the optical axis.

Here, the movement of the third lens group G ₃ is a zoom Kengoase lens group and the fourth lens group G _4, will be described with reference to Figures 4A and Figure 4B.

Figures 4A and Figure 4B is the zoom cam CZ3, the first barrel 10 and the focus cam CF ₃ having a CZ4, second barrel having a CF ₄ 20
FIG. 4A shows a change in the focused state due to the movement of both lens barrels in the optical axis direction, and FIG. 4B shows a change in the zoom state due to the relative rotation of both lens barrels. Is shown.

At the time of focusing, as shown in Fig.
Focus cam CF for the first lens barrel 10 having CZ3 and CZ4
3. The second lens barrel 20 having CF4 is moved along the optical axis by ΔF to the image side (right side in the figure). Therefore, the intersection of the zoom cam CZ3 and the focus cam CF3 ₁ in focus at infinity g
₃₁ is moved to the intersection g ₃₂ between the focus cam CF3 ₂ after relative displacement along zoom cam CZ3, resulting in the third lens group G ₃ is to be moved to the image side? Xf ₃ in the optical axis direction. Further, the intersection g ₄₁ of zoom cam CZ4 and focus cam CF4 ₁ in the infinity in-focus state is moved to the intersection g ₄₂ between the focus cam CF4 ₂ after relative displacement along zoom cam CZ4, the fourth lens group G ₄ Moves to the image side by ΔXF ₄ in the optical axis direction. Thus, the second lens barrel 20 is connected to the first lens barrel 10.
By moving in the optical axis direction by ΔF with respect to
The third lens group G ₃ and the fourth lens group as a zooming Kengo Asegun
G ₄ can be moved on the optical axis by ΔXF ₃ and ΔXF ₄ , respectively, thereby focusing on a desired object distance.

On the other hand, at the time of zooming, as shown in FIG. 4B, the first lens barrel 10 having the zoom cams CZ3 and CZ4 is perpendicular to the optical axis with respect to the second lens barrel 20 having the focus cams CF3 and CF4. It is rotated by φ (upward in the figure). Therefore, the position of the third lens group G ₃ defined by the intersection g ₃₁ between the focus cam CF3 with zoom cam CZ3 ₁ at a certain magnification state,
After the relative rotational displacement is moved to a position defined by the focus cam CF ₃ and the intersection g ₃₃ with zoom cam CZ3 ₂ indicated by a broken line, the movement amount on the optical axis becomes ΔXZ _3. Further, in the fourth lens group G _4, position determined by the intersection g ₄₁ between the focus cam CF4 and zoom cam CZ4 _1, after the relative rotational displacement, the zoom cam CZ4 ₂ shown in the focus cam CF4 and dashed moves to a position defined by the intersection g _43, amount of movement on the optical axis becomes ΔXZ _4. As described above, by rotating the first lens barrel 10 relative to the second lens barrel 20 by φ in the direction orthogonal to the optical axis, the third lens group G ₃ and the fourth lens group as a zooming and focusing group are formed. group G _4, respectively ΔXZ _3, can move on only the optical axis ΔXZ _4, whereby the transition to the desired zooming state is made.

As described above, by using the movement locus after conversion, focusing can be performed by moving along the movement locus (zoom cam) in which the zooming / focusing lens group moves during zooming. Can be That is, at the time of zooming, one of the focus cams (linear trajectories for guiding the first and second lens groups) or the zoom cam is moved in the θ direction orthogonal to the optical axis to change the position of each lens group on the optical axis. In focusing, the focus cam is set to ΔF even if the amount of movement of each focusing lens unit in the optical axis direction is different for the same photographing distance (in the first embodiment, R = 1.0 m and ΔF
= −2.4mm) to focus.

Table 3 shows the photographing distances R = 0.85, 1.0, 1.5, 2.0, and the focal lengths F = 36, 50, 60, 70, 85, and 102 mm calculated from the converted movement trajectories shown in FIG. 3.5, 5.0m
The extension amount ΔF (DF) of the second lens barrel having the focus cam for focusing at the time of, the actual extension amount ΔX (DX) of each lens group corresponding to ΔF, and the optical axis Is the displacement (BF) of the imaging point when the displacement ΔX is given. The upper part of Table 3 shows the amount of displacement (BF) of the imaging point at various photographing distances R in each zooming state, and the middle part of the focus cam required for optimal focusing at each photographing distance R. The movement amount ΔF (DF) is shown. It should be noted that the movement amount ΔF (DF) of the focus cam is a value selected such that the displacement of the imaging point at the telephoto end is eliminated.
The lower part shows the actual extension amount ΔX (DX) of each lens group corresponding to each ΔF, and the focal length F = 36, 50, 60, 70, 8
Shooting distance R = 0.85 in each zoom state of 5, 102 mm, 1.
0, 1.5, 2.0, 3.0, and 5.0 m are shown.
In the lower row, the leftmost number indicates the focal length F of the entire system,
The right end indicates the photographing distance R, and the numbers in the middle indicate the actual extension amounts ΔX (for the first lens group G ₁ , the second lens group G ₂ , the third lens group G _3, and the fourth lens group G ₄ ) in this order. DX). It should be noted that, for any value, the case of moving to the object side is shown as a positive value.

From Table 3, the amount of displacement of the imaging point at each focal length and shooting distance is small, at most about 0.067 mm, and is well within the depth of focus in any zoom state and for any object distance. ing. Therefore, by a very simple mechanism of relative movement in the optical axis direction between the second lens barrel having the focus cam and the first lens barrel having the zoom cam, good focusing is always achieved over the entire zoom range. Recognize.

From the above, even if the magnification amount, the shooting distance, and the amount of focus at the time of focusing differ depending on the focusing group, the focus cams CF1, CF2, CF3, CF4 and the zoom cams CZ1, CZ2, CZ
(3) By setting a new variable ΔF as a relative movement amount in the optical axis direction with CZ4, the movement amount of the moving member required for focusing does not change depending on the magnification state. It is clear that this is achieved with an amount ΔF and can correspond to a so-called manual focus. It should be noted that the relative movement amount ΔF of the two cams in the optical axis direction changes according to the object distance, as shown in the middle part of Table 3.

Next, Table 4 shows the value of ΔF necessary for completely optimizing the amount of displacement of the imaging point due to focusing to zero, for each magnification state and shooting distance R from the moving locus after conversion. It is what I sought. The upper part of Table 4 shows the focal length F = 36, 50, 60, 7
Shooting distance R = 0.85 in each zooming state of 0, 85, 102 mm,
The optimum extension amount ΔF (DF) of the second lens barrel having the focus cam for focusing at 1.0, 1.5, 2.0, 3.0, and 5.0 m is shown. 2 shows the amount of movement of the focus cam necessary for achieving optimum focusing. The lower part shows the value of the actual extension amount ΔX (DX) of each lens group corresponding to each ΔF, and the focal length F = 36, 5
Shooting distance R in each zooming state of 0, 60, 70, 85, and 102 mm
= 0.85, 1.0, 1.5, 2.0, 3.0, and 5.0 m are shown.

From the respective values in the upper row of Table 4, it can be seen that the value of ΔF is extremely close for the same photographing distance R, and the amount of change accompanying zooming is extremely small. Therefore, even when the first lens barrel having the zoom cam and the second lens barrel having the focus cam are relatively displaced in the optical axis direction using the autofocus, the amount of correction is extremely small. It is clear that the responsiveness is improved.

FIGS. 5A to 5F show the respective focal lengths F = 36, 50, 60, 70, 85, and 102 mm when the photographing distance is infinity, with respect to the first embodiment used for the principle explanation of the present invention. Various aberration diagrams in the doubled state are shown. FIGS. 5G to 5L also show that the present invention can be obtained with respect to the photographing distance R = 0.85 m in the respective variable power states of the focal lengths F = 36, 50, 60, 70, 85, and 102 mm. When focusing is performed by giving the relative displacement ΔF on the optical axis between the first lens barrel and the second lens barrel calculated from the converted movement trajectory (the axial displacement ΔX of each lens group is shown in Table 3). Pointing out toungue)
Are shown.

The moving trajectory is determined from ΔX, φ, and ΔF at the shooting distance R = 1.0 m. Although the amount of extension corresponding to R = 0.85 m is dependently determined from the moving trajectory, various aberrations are obtained. From the comparison of the figures, the short-range aberration fluctuation is extremely small, which indicates the effectiveness of the present invention.

Incidentally, the relationship between the focus cam and a zoom cam after conversion shown in FIG. 2, for intersecting angle of the focus cam and the zoom cam of the fourth lens group G ₄ becomes small at the telephoto side, No focus magnification and focus Occasionally, a mechanical problem for moving the lens group along the cam groove may occur. However, in such a case, by expanding or reducing all the trajectories after the conversion in the θ direction proportionally,
Only the intersection angle between the two cams can be changed without affecting the operation for zooming and focusing. As another method, it is possible to set ΔF in consideration of the intersection angle in advance.

Description of the case above to focus while performing floating by the relative movement between the table 1 and the second in the zoom lens system of the four groups the configuration shown in FIG., The third lens group G ₃ fourth lens group G ₄ Although there was a, to allow focusing is not limited to the movement of the third lens group G ₃ and the fourth lens group G _4, is also focusing is possible by the movement of groups other lens, the other It will be described below that the present invention is similarly applicable to the focusing method.

Table 5, in the zoom lens system of the four-group configuration of the first embodiment, shows the photographing distance R = converted value as feed-out amount ΔX with respect to 1 m phi in the case of performing the focusing by the movement of only the third lens group G _3, Table 6 shows [Delta] X, the φ for R = 1 m when performing focusing by moving only the second lens group G _2. Further, Table 7 shows the feeding amount ΔX and converted value φ for R = 1.5 m in the case of performing focusing only by the movement of the first lens group G ₁ is a group forefront lens.

FIG. 6 shows the movement locus after conversion in the case of focusing by the third lens group, which is converted using ΔX, φ and ΔF = −1.0 mm in Table 5 in the conversion relation diagram of FIG. 3A. It was done. Then, the amount of focus ΔF, ΔF for focusing at each focal length and shooting distance calculated from the converted movement locus.
Table 8 shows the displacement of the imaging point when X and ΔX were given in the same manner as in Table 3 above.

Similarly, FIG. 7 shows the movement trajectory after conversion when the focusing according to the second lens group G _2, which in such conversion operation of conversion relationship diagram shown in FIG. 9, [Delta] X in Table 6, φ
And ΔF = 2.0 mm with respect to the shooting distance R = 1 m. Then, the focal length calculated from the moving trajectory after the conversion and the feeding amount Δ for focusing at the shooting distance.
Table 9 shows F, ΔX, and the amount of displacement of the imaging point.

Similarly, FIG. 8 is a movement locus after conversion when the focus of the first lens group G _1, which is in the conversion operation of converting relationship diagram of FIG. 9, [Delta] X in Table 7, the value of φ , Shooting distance R
= 1.5 m and converted as ΔF = 10.0 mm. Each of the focal lengths calculated from the converted trajectories and the feeding amounts ΔF, ΔX,
Table 10 shows the displacement of the imaging point.

Note that the conversion operation based on the conversion relationship diagram shown in FIG.
This is exactly the same as the case described in FIGS. 3A and 3B, except that the moving direction at the time of focusing is reversed.

From Tables 8, 9 and 10 above, it can be seen that the displacement of the imaging point is small and sufficiently within the depth of focus in any case, and that the focusing method according to the present invention is similarly effective.

From the above results, in the zoom lens system shown in Table 1 and FIG. 1, the present invention can be used for virtually any focusable lens group. In any focusing method, the moving amount ΔF required for focusing can be maintained substantially constant for a fixed photographing distance R regardless of the zoom state or less, and the extension amounts of the plurality of focusing groups are reduced. It can be seen that good focusing can be achieved even in different cases.

Next, it will be described that the present invention is not limited to the above-described four-unit zoom lens system, but is also effective when applied to another zoom lens system.

The zoom lens system shown in FIG. 10 includes, in order from the object side, a first lens group G _{1 having} a positive refractive power, a second lens group G _{2 having} a negative refractive power,
A third lens group G _{3 having} a positive refractive power, a fourth lens group G _{4 having} a negative refractive power,
And are those of five lens groups having a positive refractive power fifth lens group G _5, upon zooming from the wide-angle side to the telephoto side, a configuration in which all the lens groups are moved toward the object side. The specifications of this zoom lens system are shown in Table 11, and the movement locus of each lens unit during zooming is also shown in the lens configuration diagram of FIG. Here, a horizontal axis such that the straight line forms an angle of 45 ° movement locus during zooming of the third lens group G ₃ is with respect to the optical axis (optical axis direction)
And the vertical axis (θ direction) are selected.

Next, in this zoom lens system, the third lens group G ₃ , the fourth lens group G _4, and the fifth lens group G ₅ are so-called, in order to suppress short-range aberration fluctuation at a photographing distance of 1.5 m and maintain high performance. Table 12 shows the amount of movement ΔX in the optical axis direction and the converted value φ in the θ direction when focusing was achieved by moving while floating.

Then, in FIG. 11, in the conversion operation as shown in the conversion relationship diagram shown in FIG. 3A, in ΔX and φ shown in Table 12,
The moving locus after conversion is shown assuming that ΔF = -1.3731 mm with respect to the shooting distance R = 1.0 m.

In FIG. 11, the movement locus of each lens group is translated in the θ direction so that the movement locus of each lens group after conversion does not interfere with each other. On the metal structure, if the cam of each lens group is turned off so as to prevent such interference, it is possible to correspond to the locus before conversion without any problem. At the time of zooming, one of the focus cam and zoom cam is relatively moved in the θ direction to change the position of each lens group on the optical axis to perform zooming. Focus is achieved by moving the focus cam by ΔF in the optical axis direction.

Then, the focal length calculated from the moving locus after the magnification change, the feeding amount ΔX (DX) for focusing at the shooting distance,
Table 13 shows the displacement (BF) of the imaging point when ΔF (DF) and ΔX were given. Also, the 12A
FIG. 12 to FIG. 12F show the focal lengths F = 28.8, 3 at the infinity shooting distance for the zoom lens systems shown in Table 11.
Various aberration diagrams in the respective zoom states of 5, 50, 70, 105, and 146 mm are shown. FIGS. 12G to 12L also show that, according to the present invention, the photographing distance R = 1.5 m in each zooming state with the focal length F = 28.8, 35, 50, 70, 105, and 146 mm. The first lens barrel and the second lens barrel calculated from the converted
Various aberration diagrams are shown when focusing is performed by giving a relative displacement ΔF on the optical axis with respect to the lens barrel (the axial displacement of each lens group is ΔX shown in Table 13).

From Table 13, it can be seen that the amount of displacement of the imaging point is small and well within the depth of focus. Further, from the aberration diagrams, it is apparent that extremely excellent imaging performance is maintained over the entire zoom range, not only at infinity but also at the time of close-range imaging.

From the above, it can be seen that even in the present embodiment, a constant ΔF can be set even if the magnification amount, the shooting distance, and the extension amount for each focusing lens group are different, and it is possible to sufficiently cope with so-called manual focusing. .

Further, a case in which the present invention is applied to a focusing system based on the whole extension of a zoom lens system will be described.

The zoom lens shown in FIG. 13 are those from the object side arrangement of two groups including the first lens group G ₁ having a negative refractive power in the order positive refractive power second lens group G ₂ Metropolitan of each lens group The magnification is changed by moving with respect to the image plane. Table 14 shows the specifications of the two-unit zoom lens system. In addition, the movement trajectory at the time of zooming is also shown in the lens configuration of FIG. Here, choose abscissa (optical axis direction) and the vertical axis (theta-direction) so that a straight line forming a 45 ° angle movement locus during zooming of the second lens group G ₂ with respect to the optical axis It is.

Next, in this zoom lens system, Table 15 shows the amount of movement ΔX in the optical axis direction and the converted value φ in the θ direction when the entire lens is extended and focused for a shooting distance of 1.5 m.

Then, in FIG. 14, a conversion operation as shown in the conversion relationship diagrams shown in FIGS. 9 and 15 is performed, and in the values of ΔX and φ in Table 15, the displacement amount in the optical axis direction with respect to the photographing distance R = 1.5 m The moving locus after the conversion obtained by converting ΔF to ΔF = 5.0 mm is shown.

In the Figure 14, so as not to move locus interference between the first lens group G ₁ after conversion and the second lens group G _2, Aru the movement locus of each lens unit moves parallel to the θ direction. As described above, if the cam of each lens group is turned off so as to prevent interference in the metal structure, the trajectory before conversion can be corresponded without any problem. At the time of zooming, zooming is performed by moving one of the focus cam and the zoom cam in the θ direction. At the time of focusing, the focus cam is moved by the same amount ΔF in the optical axis direction for the same photographing distance regardless of the zooming state. You can focus by moving.

Then, the focal lengths calculated from the converted trajectories, the feeding amounts ΔX and Δ for focusing at the respective photographing distances.
Table 16 shows the displacement of the imaging point when F and ΔX were given, as in Table 3. From Table 16, it can be seen that the amount of displacement of the imaging point is small, and is sufficiently within the depth of focus in any in-focus state.

From the above, it can be seen that the present invention can be used also in the entire extension system of the zoom lens system, and can sufficiently cope with so-called manual focus.

As described above, in various zoom lens systems, even when various focusing methods are assumed, by using the present invention, it is possible to perform focusing by manual focusing which cannot be conventionally performed.

The present invention is based on the fact that, in practically any zoom lens system, as long as a realistic focusing solution exists, all zoom lens systems except for the lens group fixed to the image plane during zooming move. This is an epoch-making method that can be applied to the focusing method of (1) and enables focusing by manual focus.

By the way, so far, as a conversion relation diagram, FIG. 3A, FIG.
As described above with reference to FIG. 3B, FIG. 9 and FIG. 15, the conversion relationship is, as described above, the moving direction of the focusing lens group during zooming, the moving direction during focusing, and the sign of ΔF. , And ΔX and Δ
Various cases can be considered depending on the magnitude relationship of F and the like. Accordingly, conversion relation diagrams for all cases of the conversion operation of the movement trajectory in the present invention are summarized in FIGS. 16 to 23. In each of these figures, the moving direction of the focusing lens unit during zooming, the moving direction during focusing, the direction of ΔF (the object side is positive), and the magnitude relationship between ΔX and ΔF are symbolized at the top of each figure. Shown. These symbolic descriptions are described in Section 3A above.
FIG. 3, FIG. 3B, FIG. 9 and FIG. In each of the conversion relation diagrams, the trajectories are all shown as straight lines in order to avoid complexity, but it is clear from the conversion trajectories of the above-described embodiments that the conversion trajectory over the entire zoom range is non-linear. is there.

16 to 23 in FIGS. 16 to 23, FIG.
FIG. 21 and FIG. 18, FIG. 18 and FIG. 22, and FIG. 19 and FIG. 23 have a corresponding relationship, and the corresponding relationship diagram can be replaced by changing the sign of ΔF. That is, in the present invention, when a certain focusing method is selected, there are two types of conversions in which the sign of ΔF is different.

Therefore, as a specific example, another converted trajectory corresponding to the converted trajectory shown in FIG.
Shown in the figure. FIG. 2 shows the movement trajectory of the zoom lens system shown in Table 1 and FIG. 1, and uses ΔF = −2.4 of ΔX and φ in Table 2 in the conversion relation diagram of FIG. 3 (same as FIG. 16). FIG. 24 is a diagram obtained by converting the movement locus of the same zoom lens system into the conversion relationship diagram of FIG. 20 (corresponding to FIG. 16) using the values in Table 2 and ΔF = 2.9. .

Then, the focal lengths calculated from the converted movement trajectories in FIG. 24 and the extension amounts ΔF, ΔF for focusing at the photographing distances are shown.
Table 17 shows the amount of displacement of the imaging point when X was given. table
From FIG. 17, it can be seen that the displacement amount of the imaging point is sufficiently small even with another corresponding conversion, and it is possible to sufficiently cope with manual focus. When the crossing angle between the focus cam and the zoom cam after the conversion is small and there is a problem with the hardware structure, as described above, if all the trajectories after the conversion are proportionally enlarged or reduced in the θ direction, zooming and focusing can be performed. Only the angle can be changed without affecting it. Alternatively, considering the intersection angle in advance, Δ
F may be set.

In the above description, when ΔX is converted into φ, the moving trajectory of any lens group before conversion is selected to be 45 ° with the optical axis, but this is also for convenience.

Table 18 shows the focus cam and zoom cam after conversion and the focus cam of each lens group corresponding to Table 3 and the X (optical axis) direction and the X (optical axis) direction on the zoom cam. The cam data indicating the coordinates with the φ direction is shown.

From the left end of Table 18, φf (n) represents coordinates in the φ direction orthogonal to the X (optical axis) direction on the focus cam of the n-th lens unit, and Xf (n) represents the coordinates on the focus cam of the n-th lens unit. Represents the coordinates in the X (optical axis) direction, φz (n) represents the coordinates in the φ direction orthogonal to the X (optical axis) direction on the zoom cam of the n-th lens unit, and Xz (n) represents the n-th lens group. F represents the focal length, R represents the coordinates of the lens group on the zoom cam in the X (optical axis) direction.
Represents the shooting distance.

Table 18- (1) shows cam data of the first lens group and the second lens group. The focus cams of the first and second lens groups are linear guide grooves parallel to the optical axis. Since the coordinates on the zoom cam do not change regardless of the shooting distance R, the column of the shooting distance R is omitted.

Table 18- (2) shows the cam data of the focus cam and zoom cam of the third lens group at each focal length F and each shooting distance R, and Table 18- (3) shows each focal length F and each shooting distance. 11 shows cam data of a focus cam and a zoom cam of the fourth lens group at a distance R.

Table 18 shows that the coordinates at F = 36 and R = ∞ are used as the origin for each lens group, and the converted focus cams CF3 and CF4 shown in FIG.
Φf (3), φf respectively corresponding to the amount of movement of the third and fourth lens groups in the φ direction (direction perpendicular to the optical axis) above
Regarding (4), the downward movement in the figure is positive, and φz (3) and φz (4) corresponding to the amounts of movement of the third and fourth lens groups in the φ direction on the zoom cams CZ3 and CZ4, respectively. The downward movement in the figure is indicated as positive. Also, Xf (3) and Xf corresponding to the amounts of movement of the third and fourth lens groups in the X (optical axis) direction on the focus cams CF3 and CF4, respectively.
Regarding (4), the movement to the left (object side) in the figure is defined as positive, and X of the third and fourth lens groups on the zoom cams CZ3 and CZ4.
Xz (3) and Xz respectively corresponding to the movement amount in the (optical axis) direction
Regarding (4), the movement on the left side (object side) in the figure is also expressed as positive.

Next, referring to FIG. 26, when the focal length is F = 36 in the cam data table of Table 18, the photographing distance is changed from R = ∞ to R = 15.
This table will be described by taking as an example the movement of the third lens group when focusing on 00.

As shown in FIG. 26, CZ3 zoom cam of the third lens group, CF3 ₁ the position of the focus cam in the state of R = ∞, CF3 ₂
Indicates the position of the focus cam when R = 1500. When the focusing distance is changed from R = ∞ to R = 1500, as shown in FIG.
The third lens group moves from CF3 ₁ to CF3 ₂ in the X direction (optical axis direction) by ΔF (ΔF = −1.5723 according to Table 3), and the position of the third lens group determined by the intersection of the focus cam and the zoom cam is as follows. to move from g ₃₁ to g _32.

At this time, as shown in Table 18 (2), the zoom cam CZ3
It can be understood that the amount of movement of the third lens unit in the X direction (optical axis direction) moving upward is Xz (3) =-1.2308, which is consistent with Table 3 shown above. At the same time, the amount of movement of the third lens unit in the X direction (optical axis direction) moving along the focus cam is as shown in Table 18- (2).
Xf (3) = 0.3415.

Here, as can be seen from FIG. 26, the shooting distance is R = ∞
Focus cam indicated by the dotted line from the focus cam CF3 ₁ showing the actual movement amount [Delta] F (solid line in the X direction of the focus cam caused by focusing the R = 1500 (optical axis direction) from CF3 ₂
The amount of movement in the direction of the optical axis in the optical axis direction) is obtained from the values of Xz (3) = − 1.2308 and Xf (3) = 0.3415 obtained from Table 18- (2).
ΔF = Xz (3) −Xf (3) = − 1.5723. It can be understood that this value is equal to ΔF = −1.5723 shown in Table 3.

On the other hand, as shown in Table 18 (2) of the same table, when the focus cam is moved from CF3 ₁ CF3 ₂ to the position, the zoom cam CZ
The amount of movement of the third lens unit that moves upward along the direction 3 in the φ direction (direction perpendicular to the optical axis) is Xz (3) = − 0.7891, and at the same time, the third lens unit that moves along the focus cam The amount of movement of the three lens units in the φ direction is Xf (3) = − 0.7891.
That is, from the specific numerical values shown in FIG. 26 and Table 17- (2), the φ direction (the direction perpendicular to the optical axis) for both cams
It can be understood that the movement amounts at the same time.

As described above, when the zoom cam and the focus cam shown in Table 18 are used for focusing, the third cam and the fourth cam shown in Table 3 are used.
It can be seen that an optical movement amount in the X direction (optical axis direction) of the lens group can be obtained.

Next, referring to FIG. 27A and FIG. 27B, the focal length F =
For example a third movement of the lens group G ₂ when zooming (zooming) to F = 102 to 36, described in detail the table.
Then, with reference to FIGS. 27C and 27D, the focusing distance from R = ∞ to R = 1500 in the state of the focal length F = 102 in the cam data table of Table 18 (focusing) This table will be described in detail by taking the movement of the third lens group at the time of) as an example.

Section 27A diagrams focal length F = 36, the focus cam CF31 of the third lens group G ₃ in the state of the photographing distance R = ∞ and Bimukamu
This shows the state of CZ3. The cam data in Table 18 uses the position where the focus cam CF31 and the zoom cam CZ3 intersect as the origin of each cam with reference to the state of the focal length F = 36 and the shooting distance R = ∞. That, O _CF31 (0,0) shows the origin of the coordinates on the focus cam CF31, O _CZ3 (0,
0) indicates the coordinates of the origin on the zoom cam CZ3.
27A and FIGS. 27B to 27D, which will be described later, show the vertical direction of the paper surface as φ direction and the horizontal direction (optical axis direction) as X direction, and each coordinate is (φ, X). Represents.

Now, with the photographing distance R = ∞, the focal length is set to F = 36.
From the zooming to F = 102, from the gum data in Table 18 (2) the third lens group G _3, the coordinates of on focus cam CF31 focal length F = 102, as shown in 27A Figure, A _CF31 (−
33.6686, 17.3820), while the coordinates on the zoom cam CZ3 with the focal length F = 102 are A _CZ3 (9.2550, 17.3820).

Therefore, the magnification change from F = 36 to F = 102 with the photographing distance R = ∞ is performed by A _CF31 (−33.6686,1
7.3820) and A _CZ3 (9.2550,17.3820).

Specifically, as shown in FIG. 27B, the focus cam CF3
1 and zoom cam CZ3 relatively in the φ direction Δφ = φZ
(3) _A- φf (3) _A = 42.9236 is moved to change the state of the focus cam CF31 indicated by the dotted line to the state of the focus cam CF32 indicated by the solid line.

At this time, since the state of the focus cam CF31 indicated by the dotted line changes from the state of the focus cam CF31 indicated by the solid line to the state of the focus cam CF31, the origin O _CF31 (0,0) of the focus cam CF31 becomes O _CF32 (0,0).
Move to the position. _ACF31 (−33.6686, 17.
3820) moves to _ACF32 (-33.6686, 17.3820). still,
The coordinates of A _CF32 (−33.6686, 17.3820) on the focus cam CF32 are shown with reference to the origin O _CF31 (0,0) on this cam.

Therefore, A _CF31 on the focus cam _CF31 (−33.686,1
A _CF32 (−3) on the focus cam CF32 corresponding to (7.3820)
3.6686,17.3820) is A _CZ3 (9.2550,
If they match and 17.3820), the third lens group G ₃ will move only DerutaXZ ₃ = 17.3820 in the optical axis direction (X-direction).

Here, the value of ΔXZ ₃ (= 17.3820) corresponds to the first position (focal length F = 36, shooting distance R = ∞) and the sixth position (focal length F = 102, it is found that matches the object distance R = ∞) the amount of movement of the third lens group G ₃ obtained from the air gap variation for each group in.

Therefore, while maintaining the state of the shooting distance R = ∞,
It can be seen that the focal length has been accurately scaled from F = 36 to F = 102.

Next, the focal length F = 102 and the photographing distance R shown in FIG. 27B
From the state of = ∞, focusing is performed on the shooting distance R = 1500.

Then, from Table 18 (2) of the third lens group G ₃ of the cam data, coordinates on focus cam CF32 shooting distance R = 1500 is, as shown in 27C view, origin O _CF32 (0,0) _BCF32 (−33.6959, 17.3967) on the basis of, while the coordinates on the zoom cam CZ3 at the shooting distance R = 1500 are the origin O _CZ3 (0,
B _CZ3 (9.2277,15.8244) based on 0).

Therefore, focusing on the focal length from R = ∞ to R = 1500 with the focal length F = 102 is performed by B _CF32 (−33.695
9,17,3967) and B _CZ3 (9.2277,15.8244).

Specifically, as shown in FIG. 27D, the focus cam CF3
2 relative to the zoom cam CZ3 in the X direction (optical axis direction)
By moving F = XZ (3) _B− Xf (3) _B = −1.5723, the state of the focus cam CF32 indicated by the dotted line may be changed to the state of the focus cam CF33 indicated by the solid line.

At this time, since the state of the focus cam CF32 indicated by the dotted line changes from the state of the focus cam CF32 indicated by the solid line to the state of the focus cam CF33, O _CF32 (0,0) at the origin of the focus cam CF32 becomes O _CF33 (0,0).
In the X direction. Accordingly, B _CF32 (−33.
6959, 17.3967) moves to _BCF33 (-33.6959, 17.3967).

Therefore, B _CF32 on the focus cam _CF32 (-33.6959,1
7.3967) B _CF33 on the focus cam _CF33 (−3
3.6959, 17.3967) is B _CZ3 (9.2277,
If they match and 15.8244), the third lens group G ₃ will move only ΔXF ₃ = -1.5576 in the optical axis direction (X-direction).

Here, it can be seen that the value of ΔXF ₃ (= 1.5576) matches the value in the lower part of Table 3- (2) shown above. Further, it can be seen that the relative movement amount ΔF (DF in Table 3) in the X direction (optical axis direction) between the focus cam CF32 and the zoom cam CZ3 matches the value in the middle part of Table 3 shown above.

Therefore, it can be understood that focusing from R = ∞ to R = 102 is accurately performed while maintaining the state of the focal length F = 102.

As described above, not only the coordinate positions on the focus cam and the zoom cam of each lens group at each focal length F and each shooting distance R can be found from the cam data shown in Table 18, but also in the optical axis direction (X direction). The relative positional relationship between the lens groups can also be easily read.

Note that, although the converted cam data shown in FIG. 2 is shown in Table 18, the converted cam data for each embodiment are shown in Tables 19 to 24, respectively.

Table 19 shows the converted cam data corresponding to FIG. 6 (the focus cam and the zoom cam after conversion) and Table 8, and Table 19- (1) shows the first, second, and fourth lenses. The cam data of the third lens group is shown in Table 19- (2), respectively.

Table 20 shows the converted cam data corresponding to FIG. 7 (the focus cam and the zoom cam after conversion) and Table 9, and Table 20- (1) shows the first, third, and fourth lenses. Table 20- (2) shows the cam data of the second lens group.

Table 21 shows the converted cam data corresponding to FIG. 8 (the focus cam and the zoom cam after conversion) and Table 10, and Table 21- (1) shows the cam data of the first lens group and the table.
21- (2) shows the cam data of the second, third and fourth lens groups, respectively.

Table 22 shows the converted cam data corresponding to FIG. 11 (the converted focus cam and zoom cam) and Table 13, and Table 22- (1) shows the cams of the first and second lens groups. Table 22- (2) shows the cam data and table of the third lens group.
22- (3) shows the cam data of the fourth lens group.
(4) shows the cam data of the fifth lens group.

Table 23 shows the converted cam data corresponding to FIG. 14 (the converted focus cam and zoom cam) and Table 16, and Table 23- (1) shows the cam data of the first lens group,
23- (2) shows the cam data of the second lens group.

Table 24 shows the converted cam data corresponding to FIG. 24 (the focus cam and the zoom cam after conversion) and Table 17, and Table 24- (1) shows the cams of the first and second lens groups. Table 24- (2) shows the cam data and table of the third lens group.
24- (3) shows the cam data of the fourth lens group.

It should be noted that each of the tables just described is shown in the same format as Table 18 described in detail above, and the way of reading each table is the same as that of Table 18, so that the description is omitted.

[Effects of the Invention] As described above, according to the present invention, regardless of a change in the focal length, that is, a change in the zooming state, the moving amount of the cam barrel that moves for focusing can be maintained substantially constant. Despite this configuration, the amount of movement of the focusing lens group itself for focusing is changed in accordance with the zoom state, and when there are a plurality of focusing lens groups, the amount of movement for each focusing lens group is changed. Since it can be changed, the degree of freedom of the lens system can be maximized. For this reason, it is possible to correct short-range aberration fluctuations by so-called floating with a plurality of focusing lenses, and it is possible to always maintain excellent imaging performance stably even when photographing a close-range object as well as at infinity. It becomes possible. The focusing method according to the present invention can be applied to any lens except for a lens group fixed to the image plane at the time of zooming, as long as a practical focusing solution exists in virtually any zoom lens system. In all focusing methods by moving the group (front lens feeding, whole lens feeding, in-focus rear focus, floating, etc.), so-called manual focus can be made possible, and at the same time, the responsiveness of auto focus is dramatically improved. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a diagram showing a lens configuration of Example 1 used for the principle explanation of the present invention and a movement locus for zooming of each lens unit, and FIG. 2 is a diagram showing a zoom lens system shown in FIG. 3 lens group G ₃ and developed view of the cam locus showing the outline of the zoom cam and the focus cam after the conversion of the movement trajectory according to the present invention was performed on focusing method according to the fourth lens group G _4, the 3A and FIG. 3B is a diagram showing the conversion relationship of the conversion operation used for the conversion of the movement trajectory in FIG. 2, and FIGS. 4A and 4B are shown by a zoom cam and a focus cam corresponding to the movement trajectory converted by the present invention. FIGS. 5A to 5F are explanatory diagrams showing the principle that focusing and zooming are achieved, respectively. FIGS. 5A to 5F are various aberration diagrams in each zooming state at the time of focusing on infinity according to the first embodiment, and FIGS. 5G to 5L. Is a diagram of various aberrations in each magnification state at the time of focusing on a short distance according to the first embodiment,
FIGS. 6, 7, and 8 show the zoom lens system shown in FIG. 1 in which the third lens group G ₃ , the second lens group G ₂ , and the first lens group G ₁ are moved to focus. FIG. 9 is a development view of a cam locus showing an outline of a zoom cam and a focus cam converted by using the present invention when performing the conversion. FIG. 9 is a conversion relationship used to derive the conversion locus shown in FIGS. 7 and 8. FIG. 10 is a diagram showing a lens configuration of the zoom lens system according to the second embodiment and a movement locus of each lens unit for zooming, and FIG. 11 is a zoom lens shown in FIG. development view of the cam locus showing the outline of the zoom cam and the focus cam after conversion to enable focusing by the movement of the third lens group G ₃ fourth lens group G ₄ and the fifth lens group G ₅ in the system, No. 12A
12A to 12F are graphs showing various aberrations at the time of focusing at infinity according to the second embodiment, and FIGS. 12G to 12L are various aberrations at the time of focusing at a close distance according to the second embodiment. FIG. 13 is a diagram showing a lens configuration of a zoom lens system according to a third embodiment and a movement locus of each lens unit for zooming. FIG. 14 is a diagram showing movement of the entire lens in the zoom lens system shown in FIG. FIG. 15 is a development view of a cam locus showing an outline of a zoom cam and a focus cam after conversion to enable focusing by FIG. 15, and FIG. 15 shows an operation of a conversion relation used to derive the conversion locus shown in FIG. FIG. 16A and FIG. 16B, FIG. 17A and FIG. 17B, FIG.
FIGS.A and 18B, FIGS.19A and 19B, FIGS.20A and 20B,
Figures 21A and 21B, Figures 22A and 22B, Figures 23A and 23B
Conversion relation diagram showing a case each conversion operation for the figure conversion movement trajectory according to the present invention, respectively, FIG. 24 the third lens group G ₃ and the fourth lens group in the zoom lens system shown in FIG. 1 G _{FIG. 4} is a development view of a cam locus showing an outline of a zoom cam and a focus cam after a movement locus according to the present invention is converted by a method different from the case of FIG.
FIG. 25 is a diagram showing the relationship between the movement amount ΔX of the focusing group and the reciprocal 1 / F of the focal length and the photographing distance R in the general focusing of the zoom lens system. FIG. FIG. 9 is a diagram showing that focusing is achieved by cam data of a zoom cam and a focus cam of the third lens group converted according to the present invention;
27A and 27B are diagrams showing that zooming is achieved by the cam data of the zoom cam and the focus cam of the third lens group converted according to the present invention shown in Table 18;
FIGS. C and 27D show that focusing is achieved by the cam data of the zoom cam and the focus cam of the third lens group converted according to the present invention shown in Table 18. [Explanation of Signs of Main Parts] G ₁ … first lens group G ₂ … second lens group G ₃ … third lens group G ₄ … fourth lens group G ₅ … fifth lens group 10… … First lens barrel 20… Second lens barrel C1, C2, C3, C4, C5… Moving trajectory before conversion CF1, CF2, CF3, CF4, CF5… Locus of focus cam after conversion CZ1, CZ2, CZ3, CZ4, CZ5 …… The locus of the zoom cam after conversion

Claims (1)

(57) [Claims] 1. A zoom lens system having a lens group having both functions of zooming and focusing, the zooming lens system having both functions of zooming and focusing. A first lens barrel having a guide groove, and a second lens barrel having a focusing guide groove for moving a lens group having both functions of zooming and focusing along the optical axis for focusing. A lens having both functions of zooming and focusing by relatively rotating the first barrel member and the second barrel member around the optical axis of the zoom lens system as a center of rotation. The desired zooming is performed by moving the group on the optical axis by an amount determined by the amount of displacement of the intersection between the zooming guide groove and the focusing guide groove, and the first lens barrel member and the second The lens group having both functions of zooming and focusing by moving the lens barrel member relatively in the optical axis direction is By moving on the optical axis by an amount determined by the amount of displacement of the intersection between the groove and the focusing guide groove, focusing on a desired object is performed, and the first barrel member required for focusing on a predetermined object While maintaining the relative movement amount in the optical axis direction between the lens group and the second lens barrel member substantially constant regardless of the zoom state, focusing of the lens group having both functions of zooming and focusing is performed. The focusing guide groove is formed in a non-linear shape having a region inclined with respect to the optical axis, so that the amount of movement on the optical axis can vary according to the zoom state. Zoom lens system.