JPH10123421A - Zoom optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a zoom optical system where high variable power is made possible, aberration fluctuation is reduced through conjugate length by focusing is changed and also high performance is secured at each zooming arrangement. SOLUTION: As for the zoom optical system where a whole system is constituted of five or more lens groups and zooming is performed by mutually despondently moving three or more variable power lens groups in the direction of an optical axis; magnifications which two or more variable lens groups out of the variable power lens groups G2 , G3 bear are respectively made almost unmagnified at a specified zooming position, and a first lens group G1 is constituted of two or more low-order lens groups G11 and G12 , and focusing is performed by moving one or more low-order lens groups out of low-order lens groups at different speed in the direction of the optical axis.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a high-magnification zoom lens.

[0002]

2. Description of the Related Art Heretofore, a finite optical system has been often used in various electronic image apparatuses which require photographing and projection by an optical system in inputting and outputting an image. Specifically, the finite optical system is used for a digital still camera lens system, a close-up photographing optical system, an enlargement / expansion optical system, a reduction optical system, and a projection lens for a liquid crystal video projector. In particular, a finite single focus lens is poor in versatility, and a dedicated optical system is used for each purpose. On the other hand, a finite zoom lens has higher versatility than a single focus lens, but has few types of lenses. For this reason, for 35mm still cameras, 1
Lens systems for 6 mm cine and TV were often used.
In particular, there has been a demand for a low-magnification (approximately 1 / 50X-1 / 30X) wide-angle imaging zoom optical system for small and high-quality image input of electronic imaging equipment. Japanese Patent Publication No. 3-71686 is a zoom system in which it is difficult to increase the zoom ratio, and has a complicated zoom trajectory.
In addition, it is an optical system for a measurement projector, and strongly demands telecentricity. The zoom ratio is about 5 times, and the effective F
The number is F / 3.5-F / 6.5 and dark. Depending on the lighting conditions, it is not sufficient when photographing a dark and dark subject. On the other hand, there has been a demand for a high-performance optical system that is bright, has a wide angle, a high zoom ratio, and is stable against a change in shooting distance.

[0003]

An optical system used for an electronic image device or the like is required to have specifications corresponding to a very large number of purposes. Dedicated optical systems have been provided for various purposes. For this reason, it is necessary to design an optical system in proportion to the target number. This is very inefficient and uneconomical. In order to solve these problems, the present invention provides a high-performance, high-magnification zoom lens and easily provides an optical system suitable for a wide range of applications. There is a need for an optical system that is bright, has a wide angle of view, corrects chromatic aberration of magnification, and has little distortion at zoom magnification in order to make it an optical system that can be used for imaging systems that require high resolution. Was. Further, there has been a demand for an optical system that secures a sufficient amount of peripheral light around the screen in order to reduce shading. An object of the present invention is to provide an optical system that satisfies these requirements simultaneously. In particular, it is an object of the present invention to provide a zoom optical system which enables high zooming, has small aberration fluctuation even when the conjugate length is changed by focusing, and has high performance in each zoom arrangement.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem. That is, the entire system is constituted by five or more lens units, and three or more variable power lens units are provided. In a zoom optical system that performs zooming by moving in different optical paths in the optical axis direction, the magnifications of the two or more zoom lens groups are almost equal at specific zooming positions, and the first lens group Is composed of two or more lower lens groups, and performs focusing by moving two or more lower lens groups, which are all or a part of the lower lens groups, at different speeds in the optical axis direction. The zoom optical system is a feature.

In the present invention, of the three or more zoom lens groups, the magnifications of the two or more zoom lens groups are formed such that the magnifications at the specific zooming positions are substantially the same. In other words, all of the three or more zoom lens groups may be formed in “simultaneous magnification of all zoom lens groups” in which all the zoom lenses are at substantially the same magnification at a specific zooming position. Two or more variable power lens groups (excluding the compensator group), which are part of the variable power lens groups, are all "substantially the same magnification" at a specific zooming position, and all become approximately the same magnification. It may be formed. The configuration in which all the variable power lens groups are at the same magnification at the same time,
It has the best zooming efficiency. In the case of partial simultaneous magnification, if an attempt is made to obtain an excessively high zoom ratio, the refractive power of each group becomes strong, and it becomes difficult to correct aberrations. Further, the Petzval sum tends to be excessively negative, and it becomes difficult to correct the field curvature. However, compared to a configuration that does not even include partial simultaneous magnification, a configuration that includes simultaneous equal magnification even in a portion has better zooming efficiency. In a zoom lens having a zoom ratio of about 5 times, a variable magnification method using partial simultaneous magnification is sufficiently practical.

Here, a description will be given of an example of a system in which all the variable power lens units having the highest variable power efficiency simultaneously achieve the same magnification.
FIG. 1 shows a movement trajectory of each lens group during zooming in a reference focusing arrangement in a typical basic configuration of the present invention.
2 shows the movement trajectory of each lens group during zooming in the close focus arrangement. In this configuration, the entire system is composed of a total of five groups, of which the second to fifth lens groups constitute a zoom magnification unit. In the examples shown in FIGS. 1 and 2, the first lens group, which is a focusing lens group, includes two lower lens groups, a front group and a rear group.

The lateral magnification of each lens group is β _i (i = 1 to 5)
Assuming that the synthetic photographing magnification of the entire system is β and the magnification of the zoom magnification part is β _z , β = β ₁ β ₂ β ₃ β ₄ β ₅ β _z = β ₂ β ₃ β ₄ β ₅ However, in the system of simultaneous magnification of all the variable power lens units, at a specific zooming position c, the magnification of any of the variable power lens groups i (i = 2 to 5) is | β _c2 | ≒ 1, | β _c3 | ≒ 1, | β _c4 | ≒ 1, | β _c5 | ≒ 1 (A). As a result, | β _cz | = | β _c2 β _c3 β _c4 β _c5 | ≒ 1 at the simultaneous equal-magnification zooming position c.

In general, among the solutions satisfying the zoom equation, if the magnification of all the variator groups is the same (−1 ×), that is, if the magnification of the compensator group is also the same,
Since the two movement curves (the solution curve of the zoom trajectory) of the compensator group are connected in the same size arrangement, the trajectory can be changed mutually. The present invention positively utilizes this transfer of the orbit to make the magnification of all the variable power lens units constituting the zoom magnification unit at the same zooming position at the same magnification or a part of two or more groups. Are configured such that the magnification of the variable magnification lens unit is partially simultaneous and equal. As a result,
A zoom trajectory (zoom equation solution) that can be reliably adopted over the entire zoom region can be stably obtained. In particular, in a system of simultaneous magnification of all zoom lens groups, a high zoom ratio can be secured. Further, when the zooming position c at which the above equation (A) holds is between the wide-angle end w and the telephoto end t, the sensitivity to manufacturing tolerance is low, and it is easy to secure the imaging performance.

As described above, according to the present invention, a zoom lens having a high zooming efficiency can be obtained. However, by using the first lens group as a focusing lens group, it is easy to change the shooting distance and defocus by zooming. Can be suppressed. If the zoom magnification is increased or the aperture ratio is increased, the imaging performance is likely to be degraded due to focusing, and the performance is particularly degraded on the telephoto side due to significant aberration fluctuation. In order to correct this, in the present invention, the first lens group, which is a focusing lens group, is multi-grouped to include two or more lower lens groups,
As a structure capable of correcting various short distances such as floating, the degree of freedom of aberration correction is ensured. In addition, since the first lens group includes two or more lower lens groups, it is possible to secure a degree of freedom in correcting performance degradation due to zoom magnification at a conjugate length different from the reference shooting distance arrangement.

In the present invention, the first lens group closest to the object is the focusing lens group. However, a focusing function can be provided to the zoom magnification varying unit. However, it is necessary to avoid a region where the magnification of the focusing lens unit is equal. In addition, with such a configuration, the amount of change in the photographing distance due to zoom magnification becomes large, so that it is necessary to take a countermeasure. In particular, in an infinite system, it may not be desirable depending on how to select a zoom trajectory. The first lens group includes two or more lower lens groups, but only one lower lens group that moves during focusing may be moved, or two or more lower lens groups may be moved in an interdependent manner. Focusing may be performed by doing. In any case, it is necessary to suppress the fluctuation of aberration due to focusing, and a focusing method and a refracting power for avoiding that the incident height of the principal ray on the first lens surface is largely separated from the optical axis by the focusing movement of the first lens group. You need to adopt distribution.

In the present invention, as shown in FIGS. 1 and 2, it is preferable that the zooming position c satisfying the above-mentioned equation (A) is between the wide-angle end w and the telephoto end t. However, the present invention includes a case where the specific zooming position c at which the expression (A) is established is on the lower magnification side than the wide-angle end w or on the higher magnification side than the telephoto end t.

In the same magnification of all the variable power lens units according to the present invention, when the zoom power of the zoom power unit is the reduction power, it is preferable that each of the powers of the variable power lens units is a reduction power. Similarly, when the magnification of the zoom magnification unit is an enlargement magnification, it is preferable that all magnifications carried by each of the variable magnification lens groups are enlargement magnifications. In the example shown in FIGS. 1 and 2, at a particular zooming position c between the wide-angle end w and the telephoto end t, | β _ci | ≒ 1 (i = 2 to 5, thus | β _cz | ≒
1) It is configured to be as follows. Therefore, at the wide-angle end w and the telephoto end t, | β _wi | ≦ 1 (i = 2 to 5, and therefore | β _wz | ≦
1) | β _ti | ≧ 1 (i = 2 to 5, thus | β _tz | ≧
1) It is preferable to configure the following.

As described above, the case where the specific zooming position c satisfying the expression (A) is on the lower magnification side than the wide-angle end w is also included in the present invention.
β _ti |> | β _wi |> | β _ci | ≒ 1 (i = 2 to 5, thus | β _tz |> | β _wz |> | β _cz
| ≒ 1) is preferable. Similarly, (A)
The present invention includes a case where the specific zooming position c where the expression is satisfied is on the higher magnification side than the telephoto end t. In this configuration, | β _wi | <| β _ti | <| β _ci | ≒ 1 (i = 2 to 5, therefore | β _wz | <| β _tz | <| β _cz
| ≒ 1) is preferable.

With these arrangements, it is possible to select a zoom power arrangement with very high zooming efficiency, so that a high zooming ratio can be secured, that is, an optical system with a large zoom ratio can be achieved. In the examples shown in FIGS. 1 and 2, the zoom magnification varying unit is constituted by four lens groups, and all the variable magnification lens groups satisfy the same magnification at the same time, so that this effect is accelerated.

In the present invention, it is preferable that the sign of the refractive power of each lens unit is symmetric between the lens unit arranged from the object side and the lens unit arranged from the image side.
That is, assuming that the configuration of the entire system is all N groups, the first lens group and the N-th lens group have the same sign of the refractive power, and likewise the second lens group.
It is preferable that the sign of the refractive power of the lens group is the same as that of the (N-1) th lens group. As a method of reducing distortion, a lens configuration with high symmetry in lens shape and refractive power arrangement regarding an aperture stop can be considered. At the center of an optical system having such a symmetry, a lens group does not necessarily have to exist, as in the case where N is an even number. In a zoom lens in which a lens group forming perfect symmetry moves, correction of fluctuation of distortion should not be desired. However, in order to obtain an optical system with little distortion by zooming, it is preferable that the refractive power distribution of each lens group has a certain degree of symmetry with respect to the aperture stop or the lens group.

For example, a first lens group for focusing having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a third lens group having a negative refractive power. 4
A second lens group, a third lens group, a fourth lens group, and a fifth lens group are provided as a zoom method that includes a lens group and a fifth lens group having a positive refractive power and enables the highest zoom ratio. A zoom lens system in which the magnification is substantially the same (-1X) will be taken as an example. When analyzing the state of occurrence of distortion in the zoom optical system, it is desirable to consider the zoom optical system as a whole divided into three parts.

That is, if the lens group including the aperture stop is the middle group, the object side of the middle group is the front group, and the image side of the middle group is the rear group, the interior of each of the front and rear groups has a considerable degree. It is necessary to have a refractive power configuration and a lens configuration that can correct distortion up to this point. These uncorrected components in the front group and the rear group, and the components that could not be offset in the front group and the rear group, are corrected in the middle group and assigned to roles. By using an optical system having such a lens configuration, it can be understood that even an optical system having a lens group that moves during zooming can have a configuration with little variation with respect to distortion. On the other hand, in order to greatly reduce the distortion, the refractive power distribution inside each of the front group and the rear group is also positive, negative or negative, positive, a lens configuration capable of canceling the aberration,
It is preferable to use a refractive power distribution.

For such a reason, while the internal structure of the first lens unit, which is the focusing lens unit, is composed of a plurality of lower lens units based on a highly symmetric lens arrangement, the focusing range and Even if the zoom magnification range is extended, it is possible to easily correct aberration fluctuation due to focusing and distortion fluctuation due to zooming, and also to easily correct other aberration fluctuations. Further, a so-called micro-zoom optical system can be realized by arranging the sign of the refractive power of each lens group symmetrically between the object side and the image side and having a focusing lens mechanism.

In the case where the entire system is composed of all five groups, the fifth lens group may be a variable power lens group in addition to the second to fourth lens groups so as to obtain the highest magnification. Alternatively, the fifth lens group may be a relay lens group fixed to the image plane even during zooming. In the former case, an optical system having a large zoom ratio can be obtained, and at the same time, the amount of movement of each lens unit due to zooming can be reduced. Therefore, the incident height of the principal ray on the first lens surface can be reduced, and the lens diameter can be reduced. It is possible to

In the present invention, the first lens group is
It can be constituted by a front group having a positive refractive power and a rear group having a positive refractive power. At this time, both the groups can be extended to the object side while the movement amount of the front group is larger than the movement amount of the rear group, and the movement amount of the front group is smaller than the movement amount of the rear group. In this way, both groups can be extended to the object side. By such a focusing movement, in addition to spherical aberration and coma even at a close distance,
The balance between the magnification and the variation of the axial chromatic aberration can be optimized in relation to the reference shooting distance arrangement. As a result, even if the desired shooting distance or zoom magnification area is changed,
Compared to the system in which the entire first lens group is fed out,
It is possible to maintain stable imaging performance over a wide range. If the amount of movement of the front group of the first lens group is larger than the amount of movement of the rear group, it is particularly effective for imaging performance on the telephoto side. Conversely, if the amount of movement of the front group is smaller than the amount of movement of the rear group, it is particularly effective for image forming performance on the wide-angle side. Scorching is possible.

Further, various more desirable conditions will be described below. First, when the first lens unit, which is the focusing lens unit, includes a front unit and a rear unit, it is desirable that the following conditions be satisfied. 1.2 <f ₁₂ / f ₁ <3.5 (1) where f _{1 is} the focal length of the first lens unit in the reference in-focus position f _{12 is} the focal length of the rear lens unit in the reference in-focus position The focal length. When the value exceeds the upper limit of the expression (1), the refractive power of the front unit becomes too strong, and it is difficult and unsuitable to secure a sufficient air space between the zooming unit and the focusing unit at the wide-angle end. Below the lower limit, the refractive power of the front group becomes too weak, and the multi-group function is lost, which is not appropriate.

Next, Δx ₁₁ : the movement amount of the front group from the reference in-focus position to the closest focus position Δx ₁₂ : the movement amount of the rear group from the reference in-focus position to the closest focus position K ≡Δx ₁₂ / Δx ₁₁ represents the average moving amount ratio between the rear group and the front group. This average moving amount ratio K desirably satisfies the following condition. 0 ≦ K <1 (2a) or 1 <K ≦ 4.5 (2b)

The lower limit of the expression (2a) means that focusing is performed by moving only the front group. Therefore, the amount of movement of the front group becomes too large, and the light quantity becomes insufficient at a close distance at the wide-angle end, which is not preferable. That is, when the distance is close to the lower limit, the amount of movement of the front group becomes too large, the refractive power of the front group becomes weak at a short distance, the incident height of the principal ray is largely separated from the optical axis, and the amount of light tends to be insufficient. When approaching the upper limit of the expression (1a), the difference between the moving speeds of the front group and the rear group becomes too small, and the effect of the short distance correction and the degree of freedom of the aberration correction are lost. It is not so preferable that the effect of the short distance correction is similarly lost even if the lower limit of the equation (2b) is approached.
K = 1 means focusing by integral extension of the first lens group, and is not included in the present invention. When the value exceeds the upper limit of the expression (2b), the front group and the rear group easily interfere with each other, which is inappropriate. At the same time, if the air gap between the front group and the rear group is sufficiently ensured to avoid interference, the peripheral light quantity becomes insufficient in the reference arrangement, which is also inappropriate.

In the present invention, it is preferable that the following formula is satisfied in order to secure compactness and a large aperture ratio of the optical system. _{0.3 <| φ / f 3 |} <0.9 (3) where, phi: maximum lens surface on the most object side of the third lens group at the wide-angle end effective diameter f _i: focal length of the i-th lens unit is there.

When the value exceeds the upper limit of the expression (3), the size of the optical system is unnecessarily bright, and the size of the optical system is unnecessarily increased. In addition, the refractive power of the third lens group becomes too strong, and it becomes difficult to correct various aberrations including spherical aberration, which is inappropriate. If the lower limit of the expression (3) is exceeded, the third
The refractive power of the lens group is too weak, and the Petzval sum of the entire system is negatively excessive, which is inappropriate. Also, when a dark optical system is used to photograph a dark subject, illumination is required more frequently, which is not desirable. This is not the case when lighting. Considering only the brightness of the optical system, it may be as dark as the resolution limit by diffraction, and | φ / f ₃ | <0.35. In a dark optical system, the number of lenses in the second lens group and the third lens group can be further easily reduced.

Further, in the present invention, the magnifications β _{2 to} β ₅ carried by each lens unit other than the focusing lens unit satisfy the simultaneous equal-magnification arrangement as shown in the equation (A), and further fall within the following ranges. It is more desirable. −1.7 <β ₂ <−0.3 (4) −1.6 <β ₃ <−0.4 (5) −1.6 <β ₄ <−0.5 (6) −1.5 < β ₅ <−0.5 (7)

When the value exceeds the upper limit of the expression (4), the incident height of the principal ray at the outermost periphery of the screen passing through the first lens surface is significantly separated from the optical axis, which causes an increase in the lens diameter. And the second lens group interfere with each other and are inappropriate. further,
It is difficult to correct the outer coma aberration of the lower beam of the principal ray at the wide angle end. Below the lower limit, the second lens group and the third lens group interfere with each other and are inappropriate. When the value exceeds the upper limit of the expression (5), the incident height of the principal ray at the outermost periphery of the screen passing through the first lens surface at the wide-angle end is significantly separated from the optical axis, resulting in an increase in the lens diameter. And the third lens group interfere with each other and are inappropriate. If the lower limit is exceeded, it becomes difficult to correct spherical aberration at the telephoto end, and at the same time, the third lens group and the fourth lens group interfere with each other, which is inappropriate. When the value exceeds the upper limit of the expression (6), the incident height of the principal ray at the outermost periphery of the screen passing through the first lens surface at the wide-angle end is remarkably separated from the optical axis, resulting in an increase in the lens diameter. And the fourth lens group interfere with each other and are inappropriate. If the lower limit is exceeded, it is difficult to correct the outer coma aberration of the upper beam of the principal ray, and at the same time, the fourth lens unit and the fifth lens unit interfere with each other, which is inappropriate. When the value exceeds the upper limit of the expression (7), the third lens unit and the fourth lens unit interfere with each other at the wide angle end, which is inappropriate. If the lower limit is exceeded, the fourth lens unit and the fifth lens unit interfere with each other at the telephoto end, which is inappropriate. Further, the refractive power of the fifth lens group becomes excessively strong, and it becomes difficult to correct the zooming fluctuation of the upper frame of the principal ray. Further, the incident height of the principal ray crossing the first lens surface at the wide-angle end is largely separated from the optical axis, and the diameter of the front lens of the lens is increased, which is inappropriate.

Further, in the present invention, as described above, the magnification of all the variable power lens units may be formed so as to be the same magnification at a specific zooming position at the same time. May be formed such that the magnifications of the variable magnification lens groups at the same zooming position become the same magnification at the same time. The lens arrangement in which all the variable power lens groups or some of the variable power lens groups satisfy the same magnification at the same time does not require mathematical strictness. Good. That is, a rounding error, a magnification error range that causes a defocus such as a depth of focus on the image forming plane such as a manufacturing tolerance, and an error range due to adjustment are naturally allowed. Therefore, it also includes a zoom arrangement area that is approximately the same size at the same time within the allowable range. This is because even if an area where no zoom solution exists near the same-magnification arrangement occurs, there is no practical problem as long as the zoom area that causes a jump in focus on the image plane is small.

As a guide of a desirable allowable range, at any zooming position where the magnification β _{cj of} one of the variable power lens groups j becomes the same magnification (−1X), any other variable power lens group i
If the magnification β _ci of (i ≠ j) is within the range of the following expression, the variable power lens group i and the variable power lens group j satisfy the condition of simultaneous magnification of the present invention. 0.9 <| _βci | <1.1 (8) In the case of simultaneous magnification of all zoom lens groups, when the value exceeds the upper limit of the expression (8), the area where no zoom solution exists from the telephoto end increases, and the magnification is changed. In this case, the area where the focus is fixed becomes narrow, which is inappropriate. If the lower limit is exceeded, the area where the zoom solution does not exist increases from the wide-angle end, and the area where the focus is fixed by zooming becomes narrow, which is inappropriate. If the area without the zoom solution is widened, the area where continuous zooming cannot be achieved increases, and the practicability is remarkably reduced. However, this does not apply to the type in which the variable power lens unit has a partially simultaneous magnification.

In the present invention, it is preferable that the following expression is satisfied. 0.02 <β ₁ / β ₅ <1.0 (9) When the value exceeds the upper limit of the expression (9), the back focus becomes short, and the working distance to the object point becomes short. It is not suitable because it is difficult to secure desired magnification and working distance as a finite system. If the lower limit is exceeded, the working distance becomes unnecessarily long, which is unsuitable for use as a finite system. Further, when the magnification beta ₅ of the fifth lens group is large, it is inappropriate since the optical system back focus becomes longer increases. However, when used as an infinity system, it is easy to suppress the wide-angle end and arrange the focusing lens groups so as to be an infinity system. At this time, the lower limit can be set to 0.

In the present invention, it is preferable to satisfy the following expression. 0.7 <f ₂ / f ₄ <1.3 (10) When the value exceeds the upper limit of the expression (10), the moving amount of the second lens unit increases, interferes with other lens units, and the zooming efficiency decreases. ,
It is not suitable for obtaining a high zoom ratio. In addition, the refracting power of the fourth lens group becomes too strong, and the load on the fifth lens group increases, making it difficult to correct coma aberration above the chief ray, which is inappropriate. If the lower limit is exceeded, the refracting power of the second lens group becomes too strong, so that the telephoto end can be widened and high magnification can be achieved. This is inappropriate because the incident height is significantly different from the optical axis and the lens diameter is increased. Also, it becomes difficult to correct various aberrations such as spherical aberration and coma.

[0032]

Embodiments of the present invention will be described.
FIGS. 3, 10, 17, and 24 are lens configuration diagrams of first, second, third, and fourth embodiments of the zoom optical system according to the present invention, respectively. In all the embodiments, 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 negative lens group Is a zoom lens including a fourth lens group G ₄ having a positive refractive power and a fifth lens group G ₅ having a positive refractive power. The first lens group G ₁ includes a front group G ₁₁ having a positive refractive power and a rear group G ₁₂ having a positive refractive power. Thus the rear group G ₁₂ and the front group G ₁₁ of the first lens group, the second to
If counted in the same manner as the fifth lens group, it can be said that the zoom lens has a six-group configuration.

The first lens group G ₁₂ rear and front group G ₁₁ of the group, fed to interdependently object side for focusing, Range, is changed and area of the zooming magnification. Among the first to third embodiment, the moving amount of it is the rear group of the front group G ₁₁ G
Greater than the amount of movement of _12, in the fourth embodiment, smaller than the movement amount in the direction of movement amount rear group G ₁₂ of the front group G _11. Also the first
In the embodiment, the second to fifth lens groups G _{2 to} G ₅ are zoom magnification units that move in the optical axis direction in a dependent manner during zooming. On the other hand, in the second to fourth embodiments, the second to fourth lens groups G ₂ ~G ₄ has a zoom magnification unit, fifth
Lens group G ₅ is fixed with respect to the image plane. The fifth lens group G ₅ is the main lens group which determines the length and the exit pupil position of the back focus. The aperture stop S is, in any embodiment is disposed at the third object side 1mm lens group G _3. In any of the embodiments, the effective F value at the wide-angle end is F /
This is a very high-performance zoom optical system that is very bright at about 2.0, has a sufficient peripheral light amount at the reference shooting distance, and has little aberration variation even when the shooting distance changes.

Tables 1 to 4 show the specifications of the first to fourth embodiments. In the [Overall Specifications] of each table, ω represents a half angle of view. In [Lens Specifications], the first column is the number of the lens surface from the object side,
Column r is the radius of curvature of each lens surface, third column d is the distance between each lens surface, fourth column ν _d is the Abbe number based on the bright line spectrum d line (reference wavelength λ = 587.6 nm) of each lens, refractive index column 5 n _d to against the d line, column 6 represents the lens number. In [variable interval in zooming], d ₀ is the object point distance, R
Represents the shooting distance. Further, as shown in [Focal Length and Magnification of Each Lens Group] and [Condition Corresponding Value] in each table, each embodiment is formed so as to satisfy the above conditional expressions (1) to (10).

The first embodiment has a zoom ratio of 10 times and a lens configuration of 18 elements in 12 groups excluding a filter. The zoom scaling unit is a fifth lens group G ₅ from the second lens group G _2, the zoom scaling unit satisfies the simultaneous magnification arranged four groups. The movement of the first lens group of the front group G ₁₁ is larger than the moving amount of the rear group G _12. Another feature of this embodiment is that the second lens group G
₂ the refractive power distribution of the strengthening of the fourth lens group G _4, and a lens shape and arrangement of the third lens group G _3. Further, the zoom fluctuation of the lower coma of the principal ray is corrected by the lens arrangement and the lens shape. That is, in the first embodiment,
Having filter L ₁ parallel plane at the object side, then have a G ₁ ~G ₅ each lens. Front group G ₁₁ of the first lens group, a negative meniscus lens component curvature directed weak convex surface facing the object side L
₂ and objects made of cemented positive lens L ₂ L ₃ between the positive lens component L ₃ having a strong convex surface facing the curvature side, the rear group G ₁₂ is a positive meniscus lens component having its stronger curvature convex surface facing the object side L ₄
Consists of The second lens group G ₂ is composed of a negative meniscus lens component L ₅ toward a weak convex of curvature at the object side, a negative meniscus lens component L ₆ toward a weak convex with curvature across product side air gap, the air gap bonding of a negative meniscus lens L ₈ with its stronger curvature concave surface facing the separating material positive meniscus lens component L ₇ and the object side toward the curvature weak concave surface facing the side a negative lens L ₇ L ₈ Prefecture. The third lens group G ₃ is a positive meniscus lens component curvature directed weak concave surface facing the object side L ₉ and goods negative meniscus lens component with its stronger curvature concave surface facing the side L ₁₀
The cemented positive lens L ₉ L ₁₀ with, a biconvex lens component L ₁₁ with its stronger curvature convex surface facing the object side. The fourth lens group G ₄ is composed of a negative lens L ₁₂ L ₁₃ bonded between the positive meniscus lens component L ₁₂ with its stronger curvature convex surface facing the image side and a biconcave lens component L _13, an air space, a biconcave lens component L
₁₄ and a positive lens L ₁₄ L ₁₅ bonded to a positive lens component L ₁₅ having a convex surface having a strong curvature on the object side. The fifth lens group G ₅ includes a positive meniscus lens component L ₁₆ having a concave surface having a weak curvature toward the object side, a positive lens component L ₁₇ having a convex surface having a strong curvature toward the image side, and a concave surface having a strong curvature toward the object side. Lens L ₁₇ L bonded with negative meniscus lens component L _18
18 and a positive lens component L _{19 having} a convex surface with a strong curvature directed to the object side.
Consists of

The second embodiment has a zoom ratio of 6 and a lens configuration of 17 elements in 12 groups, excluding filters. The zoom scaling unit is a fourth lens group G ₄ from the second lens group G _2, the zoom scaling unit satisfies the simultaneous magnification arrangement 3 group. The movement of the first lens group of the front group G ₁₁ is larger than the moving amount of the rear group G _12. Another feature of this embodiment is that the second lens group G ₂
In the shape of the lens array and the lens L _11. That is, the second
Embodiment has a filter L ₁ parallel plane at the object side, then have a G ₁ ~G ₅ each lens. Front group G ₁₁ of the first lens group to an object curvatures positive lens component L ₃ bonding of with its stronger curvature convex surface facing the negative meniscus lens component L ₂ and the object side toward a weak convex surface on the side positive lens L ₂ It consists of L _3, after the group G
₁₂ is composed of a positive meniscus lens component L ₄ with its stronger curvature convex surface facing the object side. The second lens group G ₂ is composed of a negative meniscus lens component L ₅ toward a weak convex of curvature at the object side, a biconcave lens component L ₆ an air space, a biconvex lens component L ₇ an air space biconcave lens component bonding a positive lens L ₇ L ₈ Metropolitan of the L _8. The third lens group G ₃ includes a cemented positive lens L ₉ L ₁₀ of the negative meniscus lens component L ₁₀ with its stronger curvature concave surface facing the positive lens component L ₉ and the object side with a convex surface facing the object side, both comprising a convex lens component L _11. The fourth lens group G ₄ includes a negative lens component L ₁₂ having a concave surface with a strong curvature on the image side, a biconcave lens component L ₁₃ with a space between the air, and a positive lens component L _{14 having} a convex surface with a strong curvature on the object side. And negative lenses L _{13 and} L ₁₄ bonded together. Fifth lens group G
_5, a positive meniscus lens component L ₁₅ having its curvature weak concave surface facing the object side, a negative meniscus lens with its stronger curvature concave surface facing the positive lens component L ₁₆ and the object side toward the stronger curvature convex surface facing the image side It comprises a positive lens L ₁₆ L ₁₇ bonded to the component L ₁₇ and a biconvex lens component L ₁₈ .

The third embodiment has a lens configuration of 19 elements in 13 groups, excluding filters, with a zoom ratio of 5 times. While zooming unit is the fourth lens group G ₄ from the second lens group G _2, all three
Among the zoom magnification of the group, only two groups of the second lens group G ₂ and the third lens group G ₃ satisfies the simultaneous magnification arrangement. In addition, the zooming position at which the partial simultaneous magnification is at a higher magnification side than at the telephoto end. Also, the front group G ₁₁ of the first lens group
Movement amount of is greater than the movement amount of the rear group G _12. Other features of this embodiment, to secure the imaging performance, a lens array of the second lens group G ₂ and the lens L ₁₁ form the third lens group G _3. Further, zoom fluctuation of coma aberration on the upper side and the lower side of the principal ray is corrected by the lens arrangement and the lens shape. That third embodiment has a filter L ₁ parallel plane at the object side, then have a G ₁ ~G ₅ each lens. Front group G ₁₁ of the first lens group, a positive cemented lens of a positive lens component L ₃ having a strong convex surface facing the curvature a negative meniscus lens component L ₂ and the object side toward the weak convex of curvature at the object side L consisting of ₂ L _3. Rear group G ₁₂ includes a positive meniscus lens component L ₄ with its stronger curvature convex surface facing the object side. The second lens group G ₂ is composed of a negative meniscus lens component L ₅ toward a weak convex of curvature at the object side, a negative meniscus lens component L ₆ toward a weak convex with curvature across product side air gap, the air gap bonding of a negative meniscus lens L ₈ with its stronger curvature concave surface facing the separating material positive meniscus lens component L ₇ and the object side toward the curvature weak concave surface facing the side a negative lens L ₇ L ₈ Prefecture. The third lens group G ₃ includes a cemented positive lens L ₉ L ₁₀ of the negative meniscus lens component L ₁₀ with its stronger curvature concave surface facing the biconvex lens component L ₉ and the object side, a biconvex lens component L _11. The fourth lens unit G ₄ includes a positive meniscus lens component L ₁₂ having a convex surface having a strong curvature on the image side and a biconcave lens component L
_A negative lens L ₁₂ L ₁₃ bonded to a positive lens L ₁₄ L ₁₅ bonded to a biconcave lens component L ₁₄ and a positive lens component L ₁₅ having a convex surface with a strong curvature on the object side at an air gap. Consists of The fifth lens group G ₅ includes a positive meniscus lens component L ₁₆ having its curvature weak concave surface facing the object side, a biconcave lens component L ₁₇ and goods strong curvature side convex curvature directed weak concave surface facing the object side It is composed of a negative lens L ₁₇ L ₁₈ bonded to a bi-convex lens component L ₁₈ , a bi-convex lens component L _19, and a bi-convex lens component L _{20 with a} convex surface having a strong curvature facing the object side.

[0038] In the fourth embodiment has a zoom ratio of 7 times, a 12 group 17 lenses configuration except for the filter, zoom magnification unit is the fourth lens group G ₄ from the second lens group G _2, the zoom The zoom unit satisfies the three-unit simultaneous equal-size arrangement. The movement of the first lens group of the front group G ₁₁ is smaller than the moving amount of the rear group G _12. Another feature of this embodiment is that the second lens group G ₂
In the shape of the lens array and the lens L _11. That is, the third
Embodiment has a filter L ₁ parallel plane at the object side, then have a G ₁ ~G ₅ each lens. Front group G ₁₁ of the first lens group, a positive cemented lens of a positive lens component L ₃ having a strong convex surface facing the curvature a negative meniscus lens component L ₂ and the object side toward the weak convex of curvature at the object side L consisting of ₂ L _3. Rear group G ₁₂ includes a positive meniscus lens component L ₄ having a strong convex surface facing the curvature across product side air gap. Second lens group G ₂
Is composed of a negative meniscus lens component L ₅ toward a weak convex of curvature at the object side, a negative meniscus lens component L ₆ toward a weak convex with curvature across product side an air space, the curvature on the object side an air space Meniscus lens component L with a weak concave surface
Bonding a negative lens L ₇ L ₈ Metropolitan of curvature directed strong concave surface ₇ and the object side and a negative meniscus lens component L _8. The third lens group G ₃ is a positive lens component a convex surface facing the object side L ₉
And cemented positive lens L ₉ L ₁₀ of the negative meniscus lens component L ₁₀ with its stronger curvature concave surface facing the object side, a positive lens component L ₁₁ having a convex surface directed toward the object side. Fourth lens group G ₄
Is a negative lens component L having a concave surface with a strong curvature directed to the image side.
_A negative lens L ₁₃ L ₁₄ is formed by bonding a bi-concave lens component L ₁₃ with a positive lens component L ₁₄ having a convex surface having a strong curvature to the object side at an air interval. The fifth lens group G ₅ includes a positive meniscus lens component L ₁₅ having a concave surface with a weak curvature directed to the object side.
A positive lens component L ₁₆ having a convex surface having a strong curvature on the image side and a negative meniscus lens component L ₁₇ having a concave surface having a strong curvature on the object side, and a positive lens L ₁₆ L ₁₇ and a biconvex lens component L _{Consists of eighteen} .

[0039]

[Table 1] [Overall specifications] F / 2.0 to F / 4.5 1 / 5x to 1 / 50x 2ω = 39.68 ° to 3.74 ° f = 15.243 to 165.735 [Lens specifications] Nord ν _{dn d} 1 ∞ 2.000 _{64.1 1.51680 L 1 2 ∞ 1.000 3} 52.282 1.600 25.3 1.80518 L 2 4 32.482 9.000 60.2 1.51835 L 3 5 844.031 (d 5) 6 43.375 6.000 53.5 1.54739 L 4 7 363.126 (d 7) 8 60.978 1.400 49.5 1.77279 L 5 9 18.150 3.900 10 268.375 1.350 49.5 1.77279 L ₆ 11 51.622 3.000 12 -23.337 3.500 25.3 1.80518 L ₇ 13 -13.700 1.350 49.5 1.77279 L ₈ 14 -44.295 (d ₁₄ ) 15 -132.125 4.500 82.5 1.49782 L ₉ 16 -16.000 1.300 33.9 1.80384 L ₁₀ 17 -26.136 0.200 18 34.000 4.000 82.5 1.49782 L ₁₁ 19 -62.143 (d ₁₉ ) 20 -41.516 2.500 29.5 1.71736 L ₁₂ 21 -15.500 1.200 55.6 1.69680 L ₁₃ 22 156.882 2.500 23 -23.900 1.200 53.9 1.71300 L ₁₄ 24 18.500 3.500 29.5 1.71736 L ₁₅ 25 199.281 (d ₂₅ ) 26 -76.599 5.500 58.5 1.65 160 L ₁₆ 27 -22.396 0.200 28 169.243 8.500 82.5 1.49782 L ₁₇ 29 -21.000 1.400 _{25.3 1.80518 L 18 30 -58.655 0.200 31} 33.154 6.000 82.5 1.49782 L 19 32 -192.838 (d 32) Position 1 Position 2 Position 3 Position 4 Position 5 Position 6 [variable spaces at zooming in the reference focusing arrangement] β -0.0200 _{-0.0400 -0.0600 -0.1000 -0.1400 -0.2000 d 0 705.0847} 705.0847 705.0847 705.0847 705.0847 705.0847 d 5 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 d 7 2.8003 12.7987 16.7368 20.6362 22.8835 24.7653 d 14 45.8177 30.2716 22.6052 13.5234 7.4751 1.3959 d 19 7.6319 14.2001 19.0318 25.8317 30.5834 36.1520 _{d 25 11.8480 9.7180 7.8688 5.2149 3.5039 1.2933} d 32 42.1564 43.2659 44.0117 45.0481 45.8084 46.6478 R 893.1390 893.1390 893.1389 893.1390 893.1390 893.1390 position [variable spaces at zooming at close focus arrangement] 1 'position 2' position 3 'position 4' position 5 'Position 6' β -0.0300 -0.0600 -0.0900 -0.1500 -0.2100 -0.3000 d ₀ 492.7370 492.7361 492.7375 492.7358 492.7356 492.7372 d ₅ 4.5942 4.5943 4.5942 4.5943 4.5943 4.5942 d ₇ 5.1965 15.1949 19.1330 23.0324 25.2797 27.1615 d ₁₄ 45.8177 30.2716 22.6052 13.5234 7.4751 1.3959 d ₁₉ 7.6319 14.2001 19.0318 25.8317 30.5834 36.1520 d ₂₅ 11.8480 9.7180 7.8688 5.2149 3.5039 1.2933 d ₃₂ 42.1564 43.2659 44.0116 45.0 676 686.867 Focal length and magnification of each lens group in focal arrangement] Position 1 Position 2 Position 3 Position 4 Position 5 Position 6 f β _w β _c β _t G ₁ 60.000 -0.09203 -0.09203 -0.09203 -0.09203 -0.09203 -0.09203 G ₁₁ 163.6832 _{-0.30194 -0.30194 -0.30194 -0.30194 -0.30194 -0.30194 G 12} 89.3953 0.30479 0.30479 0.30479 0.30479 0.30479 0.30479 G 2 -17.5000 -0.50518 -0.71014 -0.84521 -1.04132 -1.20207 -1.38051 G 3 32.0000 -0.59271 -0.76137 -0.87129 -1.02969 -1.14935 _{-1.28589 G 4 -17.5000 -0.80956 -0.85594 -0.91473 -1.00573} -1.06206 -1.14542 G 5 26.0000 -0.89612 -0.93877 -0.96743 -1.00721 -1.03632 -1.06833 [ focal point of each lens group at close focusing arrangement Away and the magnification] position 1 'position 2' position 3 'position 4' position 5 'position _{6' f β w β c β} t G 1 60.8975 -0.13801 -0.13801 -0.13801 -0.13801 -0.13801 -0.13801 G 11 163.6832 -0.49639 - _{0.49639 -0.49639 -0.49639 -0.49639 -0.49639 G 12 89.3953} 0.27803 0.27803 0.27803 0.27803 0.27803 0.27803 G 2 -17.5000 -0.50523 -0.71025 -0.84536 -1.04155 -1.20237 -1.38092 G 3 32.0000 -0.59270 -0.76133 -0.87123 -1.02956 -1.14913 -1.28552 G _{4 -17.5000 -0.80957 -0.85598 -0.91482 -1.00597 -1.06251 -1.14630} G 5 26.0000 -0.89611 -0.93875 -0.96737 -1.00704 -1.03600 -1.06766 [ condition correspondence _{value] φ = 17.9 φ / f 3} = 0.559 K = 0.400 β 1 / β ₅ = 0.1027 f ₁₂ / f ₁ = 1.49 f ₂ / f ₄ = 1.0

[0040]

[Table 2] [Overall specifications] F / 2.1 to F / 3.9 1 / 8.33x to 1 / 50x 2ω = 40.54 ° to 6.56 ° f = 14.801 to 110.114 [Lens specifications] Nord ν _{dn d} 1 ∞ _{2.000 64.1 1.51680 L 1 2 ∞ 1.000} 3 84.814 1.500 25.4 1.80518 L 2 4 38.000 6.900 53.8 1.69350 L 3 5 711.998 (d 5) 6 34.914 4.500 57.6 1.67025 L 4 7 84.294 (d 7) 8 44.392 1.200 52.3 1.74810 L 5 9 17.923 _{5.300 10 -80.515 1.100 52.3 1.74810 L 6} 11 39.416 0.200 12 33.395 5.000 25.4 1.80518 L 7 13 -55.000 1.000 49.4 1.77279 L 8 14 40.347 (d 14) 15 85.366 2.700 82.6 1.49782 L 9 16 -26.000 1.000 25.4 1.80518 L 10 17 - 45.897 0.200 18 35.440 2.600 82.6 1.49782 L ₁₁ 19 -98.669 (d ₁₉ ) 20 40.094 1.100 60.3 1.62041 L ₁₂ 21 19.460 3.600 22 -15.929 1.100 54.0 1.61720 L ₁₃ 23 22.151 2.600 25.4 1.80518 L ₁₄ 24 -248 12.402 (d ₂₄ ) 25- 120.081 3.500 45.4 1.79668 L ₁₅ 26 -27.887 0.200 27 1148.998 5.500 82.6 1.49782 L ₁₆ 28 -17.500 1.000 25.4 1.80518 L ₁₇ 29 -42.177 0.20 0 30 45.122 4.000 82.6 1.49782 L ₁₈ 31 -57.782 37.387 [Variable interval in zooming in the reference focusing position] Position 1 Position 2 Position 3 Position 4 Position 5 Position 6 β -0.0200 -0.0400 -0.0500 -0.0800 -0.1000 -0.1200 _{d 0 693.6641 693.6641 693.6641 693.6641 693.6641 693.6641} d 5 0.2244 0.2244 0.2244 0.2244 0.2244 0.2244 d 7 0.4502 9.9375 12.3643 16.6791 18.5758 19.4169 d 14 47.6096 31.2219 26.2969 16.1963 11.0704 8.1311 d 19 2.8744 11.6378 14.8106 22.1585 25.8642 29.5441 d 24 10.5323 8.6693 7.9947 6.4326 5.9561 4.3744 R 851.7421 851.7420 851.7420 851.7421 851.7421 851.7421 [Variable spacing in zooming in close focus arrangement] Position 1 'Position 2' Position 3 'Position 4' Position 5 'Position 6' β -0.0300 -0.0600 -0.0750 -0.1200 -0.1500 -0.1800 d _{0 484.4738 484.4727 484.4742 484.4728 484.4729 484.4738 d} 5 3.4157 3.4158 3.4157 3.4158 3.4157 3.4157 d 7 2.9051 12.3924 14.8192 19.1340 21.0307 21.8718 d 14 47.6096 31.2219 26.2969 16.1963 11.070 _{4 8.1311 d 19 2.8744 11.6378 14.8106 22.1585} 25.8642 29.5441 d 24 10.5323 8.6693 7.9947 6.4326 5.9561 4.3744 R 648.1980 648.1969 648.1983 648.1971 648.1971 648.1979 [ focal length and magnification of each lens group at the reference focus Alignment Position 1 Position 2 Position 3 Position 4 Position 5 Position 6 f β _w β _c β _t G ₁ 58.8368 -0.09193 -0.09193 -0.09193 -0.09193 -0.09193 -0.09193 G ₁₁ 177.3830 -0.34220 -0.34220 -0.34220 -0.34220 -0.34220 -0.34220 G ₁₂ 85.7854 0.26864 0.26864 0.26864 0.26864 0.26864 0.26864 _{2 -19.3000 -0.56927 -0.79048 -0.87772 -1.09200 -1.22327 -1.29216} G 3 33.0726 -0.63435 -0.82645 -0.89929 -1.07339 -1.17199 -1.24289 G 4 -21.0963 -0.83666 -0.92509 -0.95715 -1.03156 -1.05449 -1.12988 G 5 24.2097 - 0.71906 -0.71901 -0.71897 -0.71880 -0.71865 -0.71846 [Focal length and magnification of each lens group in close focus arrangement] Position 1 'Position 2' Position 3 'Position 4' Position 5 'Position 6' f β _w β _c β _t G ₁ 59.5719 -0.13779 -0.13779 -0.137 _{79 -0.13779 -0.13779 -0.13779 G 11 177.3830 -0.57375} -0.57375 -0.57375 -0.57375 -0.57375 -0.57375 G 12 85.7854 0.24015 0.24015 0.24015 0.24015 0.24015 0.24015 G 2 -19.3000 -0.56946 -0.79083 -0.87816 -1.09268 -1.22412 -1.29311 G 3 33.0726 _{-0.63431 -0.82631 -0.89908 -1.07293 -1.17131 -1.24204 G 4} -21.0963 -0.83671 -0.92528 -0.95745 -1.03232 -1.05568 -1.13160 G 5 24.2097 -0.71904 -0.71892 -0.71883 -0.71846 -0.71812 -0.71769 [ condition correspondence value] phi = 15.5 φ / f ₃ = 0.469 K = 0.435 β ₁ / β ₅ = 0.128 f ₁₂ / f ₁ = 1.458 f ₂ / f ₄ = 0.915

[0041]

[Table 3] [Overall specifications] F / 2.35 to F / 3.37 1 / 10x to 1 / 50x 2ω = 38.32 ° to 7.34 ° f = 15.768 to 82.588 [Lens specifications] Nor d ν _{dn d} 1 ∞ 2.000 _{64.1 1.51680 L 1 2 ∞ 2.000 3} 69.090 1.600 25.3 1.80518 L 2 4 38.500 6.800 60.1 1.62041 L 3 5 -1771.924 (d 5) 6 35.124 4.000 60.1 1.62041 L 4 7 67.290 (d 7) 8 37.960 1.050 55.6 1.69680 L 5 9 16.167 4.000 10 198.026 1.050 52.3 1.74810 L ₆ 11 46.692 2.600 12 -33.688 2.500 25.3 1.80518 L ₇ 13 -19.000 1.000 55.6 1.69680 L ₈ 14 -502.634 (d ₁₄ ) 15 46.282 3.800 49.0 1.53172 L ₉ 16 -17.500 1.000 25.3 1.80518 L ₁₀ 17 -30.656 0.200 18 31.774 2.500 82.5 1.49782 L ₁₁ 19 -97.113 (d ₁₉ ) 20 -48.170 2.000 25.3 1.80518 L ₁₂ 21 -17.090 1.000 57.0 1.62280 L ₁₃ 22 49.377 2.300 23 -15.140 1.000 54.0 1.61720 L ₁₄ 24 18.500 2.400 27.6 1.75520 L ₁₅ 25 103.742 (d ₂₅ ) 26 -237.357 2.800 49.5 1.77279 L ₁₆ 27 -22.682 0.200 28 -97.109 1.200 25.3 1.80518 L ₁₇ 29 21.060 4.50 0 82.5 1.49782 L ₁₈ 30 -58.138 0.200 31 90.831 2.800 82.5 1.49782 L ₁₉ 32 -69.580 0.200 33 34.462 4.000 82.5 1.49782 L ₂₀ 34 -99.744 36.596 [Variable interval for zooming in the reference focusing arrangement] Position 1 Position 2 Position 3 position 4 position 5 position 6 β -0.0200 -0.0250 -0.0400 -0.0500 -0.0800 -0.1000 d 0 744.8694 744.8694 744.8694 744.8694 744.8694 744.8694 d 5 1.0000 1.0000 1.0000 1.0000 1.0000 1.0000 d 7 1.4123 5.3706 12.4149 15.3014 20.2753 22.6436 d 14 37.0109 31.9054 22.1439 17.6269 9.2107 _{5.5892 d 19 0.6391 2.1877 5.8558 7.8076 12.4721} 14.4313 d 25 4.5253 4.1238 3.1728 2.8516 1.6294 0.9234 R 886.7530 886.7529 886.7529 886.7530 886.7529 886.7530 [ variable spaces at zooming at close focus placement positions 1 'position 2' position 3 'position 4' position 5 'position 6' β -0.0300 -0.0375 -0.0600 -0.0750 -0.1200 -0.1500 d ₀ 520.7008 520.7007 520.6996 520.7008 520.6998 520.6994 d ₅ 4.0698 4.0698 4.0698 4.0698 4.0698 4.0698 d ₇ 3.7737 _{7.7320 14.7763 17.6628 22.6367 25.0050 d 14 37.0109} 31.9054 22.1439 17.6269 9.2107 5.5892 d 19 0.6391 2.1877 5.8558 7.8076 12.4721 14.4313 d 25 4.5253 4.1238 3.1728 2.8516 1.6294 0.9234 R 668.0156 668.0154 668.0143 668.0156 668.0145 668.0142 [ focal length of each lens group at the reference focusing arrangement and Magnification] Position 1 Position 2 Position 3 Position 4 Position 5 Position 6 f β _w β _t G ₁ 63.1346 -0.09166 -0.09166 -0.09166 -0.09166 -0.09166 -0.09166 G ₁₁ 138.1082 -0.22578 -0.22578 -0.22578 -0.22578 -0.22578 -0.22578 G _{12 113.0534 0.40595 0.40595 0.40595 0.40595 0.40595 0.40595} G 2 -17.4987 -0.44296 -0.49229 -0.61397 -0.68316 -0.84778 -0.95766 G 3 23.9732 -0.51300 -0.56422 -0.68776 -0.75983 -0.92151 -0.98588 G 4 -15.9999 -1.10721 -1.13234 -1.19193 - _{1.21216 -1.28918 -1.33388 G 5 22.0000 -0.86512 -0.86510} -0.86502 -0.86494 -0.86459 -0.86428 [ focal length and magnification of each lens group at close focus placement positions 1 'position 2' position 3 'position 4' position 'Position _{6' f β w β t G} 1 63.9282 -0.13730 -0.13730 -0.13730 -0.13730 -0.13730 -0.13730 G 11 138.1082 -0.35640 -0.35640 -0.35640 -0.35640 -0.35640 -0.35640 G 12 113.0534 0.38525 0.38525 0.38525 0.38525 0.38525 0.38525 G 2 -17.4987 -0.44319 -0.49258 -0.61441 -0.68370 -0.84862 -0.95873 G 3 23.9732 -0.51295 -0.56415 -0.68761 -0.75960 -0.92099 -0.98513 G 4 -15.9999 -1.10729 -1.13247 -1.19225 -1.21266 -1.29047 -1.33591 G 5 22.0000 -0.86508 -0.86503 -0.86484 -0.86466 -0.86389 -0.86318 [Conditional value] φ = 15.4 φ / f ₃ = 0.642 K = 0.435 β ₁ / β ₅ = 0.106 f ₁₂ / f ₁ = 1.79 f ₂ / f ₄ = 1.094

[0042]

[Table 4] [Overall specifications] F / 2.01 to F / 4.60 1 / 7.14x to 1 / 50x 2ω = 40.54 ° to 5.76 ° f = 14.908 to 116.246 [Lens specifications] Nor d ν _d n _d 1 ∞ _{2.000 64.1 1.51680 L 1 2 ∞ 2.000} 3 53.350 1.700 25.3 1.80518 L 2 4 30.000 9.000 47.1 1.62374 L 3 5 248.222 (d 5) 6 44.091 4.000 48.0 1.71700 L 4 7 131.849 (d 7) 8 72.167 1.200 49.5 1.77279 L 5 9 20.909 4.300 10 226.333 1.200 49.5 1.77279 L ₆ 11 54.698 3.000 12 -50.126 3.500 25.3 1.80518 L ₇ 13 -20.000 1.100 52.3 1.74810 L ₈ 14 -257.817 (d ₁₄ ) 15 67.002 3.600 82.5 1.49782 L ₉ 16 -17.200 1.000 25.3 1.80518 L ₁₀ 17 -25.574 0.200 18 24.223 2.000 82.5 1.49782 L ₁₁ 19 42.197 (d ₁₉ ) 20 32.887 1.100 60.1 1.62041 L ₁₂ 21 18.439 3.500 22 -14.235 1.100 58.5 1.65160 L ₁₃ 23 21.700 3.000 25.3 1.80518 L ₁₄ 24 -223.776 (d ₂₄ ) 25- 68.813 3.500 47.5 1.78797 L ₁₅ 26 -22.831 0.200 27 353.972 6.500 82.5 1.49782 L ₁₆ 28 -18.000 1.200 25.3 1.80518 L ₁₇ 29 -50.715 0.2 00 30 32.204 5.000 82.5 1.49782 L ₁₈ 31 -109.541 35.940 [Variable interval in zooming in the reference focusing position] Position 1 Position 2 Position 3 Position 4 Position 5 Position 6 β -0.0200 -0.0300 -0.0500 -0.0800 -0.1000 -0.1400 _{d 0 690.6850 690.6850 690.6850 690.6850 690.6850 690.6850} d 5 2.4756 2.4756 2.4756 2.4756 2.4756 2.4756 d 7 0.2076 5.5184 10.9596 14.7091 16.1684 17.5092 d 14 42.4447 32.9714 21.8779 12.4922 8.2791 3.1237 d 20 2.9757 8.4165 15.8981 23.7874 27.8589 34.9337 d 24 13.4078 12.1295 10.3003 8.0471 6.7293 3.4692 R 853.2368 853.2368 853.2369 853.2369 853.2368 853.2369 [Variable spacing in zooming in close focus arrangement] Position 1 'Position 2' Position 3 'Position 4' Position 5 'Position 6' β -0.0300 -0.0450 -0.0750 -0.1200 -0.1500 -0.2100 d _{0 475.6076 475.6091 475.6087 475.6073 475.6087 475.6086 d} 5 1.0327 1.0327 1.0327 1.0327 1.0327 1.0327 d 7 3.0934 8.4042 13.8454 17.5949 19.0542 20.3950 d 14 42.4447 32.9714 21.8779 12.4922 8.279 1 3.1237 d ₂₀ 2.9757 8.4165 15.8981 23.7874 27.8589 34.9337 d ₂₄ 13.4078 12.1295 10.3003 8.0471 6.7293 3.4692 R 639.6023 639.6038 639.6035 639.6021 639.6034 639.6034 [Focal distance and magnification of each lens group in reference focusing arrangement] Position 1 Position 2 Position 3 Position 4 5 position 6 f β _w β _c β _t G ₁ 58.8369 -0.09207 -0.09207 -0.09207 -0.09207 -0.09207 -0.09207 G ₁₁ 147.4815 -0.27144 -0.27144 -0.27144 -0.27144 -0.27144 -0.27144 G ₁₂ 90.6632 0.33919 0.33919 0.33919 0.33919 0.33919 0.339 _{2 -20.0000 -0.60711 -0.72380 -0.90127 -1.08452 -1.17771 -1.27867} G 3 33.0726 -0.64531 -0.74976 -0.90444 -1.07218 -1.16057 -1.30410 G 4 -20.0000 -0.77089 -0.83481 -0.92628 -1.03896 -1.10486 -1.26793 G 5 24.1334 - 0.71918 -0.71918 -0.71918 -0.71917 -0.71916 -0.71914 [Focal length and magnification of each lens group in close focus arrangement] Position 1 'Position 2' Position 3 'Position 4' Position 5 'Position 6' f β _w β _c β _t G ₁ 58.4657 -0.13810 -0.13810 -0.13 _{810 -0.13810 -0.13810 -0.13810 G 11 147.4815 -0.44929} -0.44929 -0.44929 -0.44929 -0.44929 -0.44929 G 12 90.6632 0.30737 0.30737 0.30737 0.30737 0.30737 0.30737 G 2 -20.0000 -0.60712 -0.72381 -0.90130 -1.08456 -1.17776 -1.27872 G 3 33.0726 _{-0.64531 -0.74976 -0.90443 -1.07216 -1.16053 -1.30404 G 4} -20.0000 -0.77089 -0.83481 -0.92630 -1.03901 -1.10494 -1.26808 G 5 24.1334 -0.71918 -0.71918 -0.71917 -0.71917 -0.71913 -0.71907 [ condition correspondence value] phi = 15.3 φ / f ₃ = 0.462 K = 2.00 β ₁ / β ₅ = 0.128 f ₁₂ / f ₁ = 1.54 f ₂ / f ₄ = 1.0

4, 5, 6, 7, 8 and 9
The spherical aberration and the astigmatism at the wide-angle end, the intermediate magnification position, and the telephoto end in the reference focusing arrangement and the wide-angle end, the intermediate magnification position, and the telephoto end in the closest focusing arrangement, respectively, for the first embodiment. , Distortion, chromatic aberration of magnification, and lateral aberration. Similarly, FIGS. 11 to 16 show various aberrations of the second embodiment.
8 to 23 show various aberrations of the third embodiment, and FIGS.
0 shows various aberrations of the fourth example. In each aberration diagram, FN is F
Number, Y is image height, d is d line, g is g line (λ = 43
5.8 nm). In the astigmatism diagram, a dotted line represents a meridional image plane, and a solid line represents a sagittal image plane.

In any of the embodiments, especially at the wide-angle end, the distortion is almost completely corrected. Therefore, since the decrease in the illuminance ratio depends on the cosine fourth power (cos ⁴ ω), it is necessary to suppress the vignetting. As is clear from the aberration diagrams, in each of the embodiments, a sufficient peripheral light amount is secured at the reference photographing distance. Since the peripheral light amount is large, the coma because aberration fluctuations suppressed from occurring in zooming, especially lower coma measures lens arrangement of the second lens group G ₂ of the principal rays, lens shape, and the third lens group G ₃ The lens shape has been devised. On the other hand, the lens arrangement of the fifth lens group G _5, devised lens shape is conscious upper coma measures of the principal ray.

In each embodiment, the first lens group G ₁
Although but is composed of a lens system 2-group structure of the rear group G ₁₂ and the front group G _11, and the lens configuration more complex, for example, by or to a lens or the like bonded to the group G ₁₂ subsequent, more In close-range shooting, imaging performance can be ensured.
6 entire system by dividing the first lens group G ₁ in this manner into two or more groups
A lens system having more than a group can be easily realized. Further, by increasing the number of bonded lenses as the lens arrangement of the fourth lens group G ₄ and the fifth lens group G ₅ , it is possible to sufficiently secure the degree of freedom to simultaneously correct axial chromatic aberration and magnification chromatic aberration on the wide-angle side. it can. In this case it is possible to reduce the load for the second lens group G ₂ achromatic.

[0046] Further, although either embodiment is also fundamental is constituted by the lens system of 5-group configuration, dividing the third lens group G ₃ to the two or more groups like the first lens group G _1, large diameter It is also possible to easily realize a lens system having six or more lens groups as a configuration in which the degree of freedom of the configuration is secured. No need for wide angle,
When the objective is sufficiently fulfilled by a dark optical system, it is apparent from each embodiment that the number of constituent lenses can be reduced.
In particular, it is much easier to enlarge the zoom region to the telephoto end and increase the zoom ratio than to expand to the wide-angle end.
Further, it is not necessary to widen the angle to shorten the conjugate length and increase the photographing magnification, so that the present invention can be easily realized. As one method of realizing this, the first lens group G
_This can be achieved by focusing by moving each part and the whole of each part group in ₁ on the optical axis.

The first lens group G ₁ which is a focusing lens group includes:
Although the zooming is fixed in the embodiment, the zooming may be moved so as to contribute to zooming. When three or more zooming units are provided, it is not always necessary for all the zooming units carried by the zooming unit to be at the same magnification. It may be used while avoiding the same magnification arrangement of a specific zooming group.

Further, according to the present invention, the effective F value at the wide angle end is F /
It is very bright, about 2.0, and the peripheral light quantity is sufficiently secured. It is bright, and the effective diameter of the first lens surface is kept small, so that the optical system is compact. In spite of this, it is considered that the reason why the various types of aberration can be satisfactorily corrected and a high-performance optical system can be realized is an efficient zoom type.
Magnification of each group, distribution of refractive power of each lens group, clever selection of zoom trajectory, and the like. Further, by using the same-size simultaneous arrangement, it is possible to suppress deterioration of the imaging performance due to a manufacturing error or the like.

Usually, when the pupil is made as close as possible to the surface of the lens end, the refractive power arrangement of the lens groups is preceded by the lens group having a negative refractive power. On the other hand, when the position of the pupil is as far as possible from the surface of the lens end, the refractive power arrangement of the lens groups is preceded by the lens group having a positive refractive power. By employing such a refractive power distribution, an image-side, object-side telecentric optical system, or an optical system close thereto can be realized. However, in the present invention, it is not necessary to be a strict telecentric optical system. The aperture stop may be at any position from between the second lens group and the third lens group to between the fourth lens group and the fifth lens group. Also, it may be spatially moved or fixed in conjunction with zooming.

[0050]

According to the present invention, the high resolution as described above,
By providing a high-performance, high-magnification zoom lens with a wide focusing area, an optical system suitable for a wide range of applications can be easily provided. In particular, a compact zoom optical system that is bright, has a short conjugate length, and has a wide angle of view can be realized. Further, an optical system in which distortion and fluctuation of distortion are very small by zooming can be realized. In addition, an optical system in which a sufficient amount of peripheral light is secured around the screen in order to reduce shading of the image pickup system was realized. By realizing an optical system that satisfies these characteristics simultaneously,
The versatility of the optical system has greatly increased. In particular, it is possible to suppress the deterioration of the imaging performance due to a large change in the conjugate length and working distance over a wide range, and it is also possible to use it as a micro zoom lens. Specifically,
This optical system includes a document lens system, a camera-type scanner, a digital still camera lens system, a TV camera lens system,
It can be used for a close-up photographing optical system, an optical system for enlargement / enlargement, a projection lens for a liquid crystal video projector, and the like. The size, conjugate length, and working distance of the photographed image and projected image can be easily set by moving and focusing the focusing lens group, and can be used in an optimal arrangement according to various purposes. Approached the lens.

[Brief description of the drawings]

FIG. 1 is a schematic view of a reference focusing arrangement showing the principle of the present invention.

FIG. 2 is a schematic diagram illustrating a principle of the present invention in a close-focusing arrangement.

FIG. 3 is a lens arrangement diagram at a wide-angle end in a reference focusing arrangement according to the first embodiment.

FIG. 4 is a diagram illustrating various aberrations at a wide-angle end in a reference focusing arrangement according to the first example.

FIG. 5 is a diagram illustrating various aberrations at an intermediate magnification position in the reference focusing arrangement according to the first example.

FIG. 6 is a diagram illustrating various aberrations at a telephoto end in a reference focusing arrangement according to the first example.

FIG. 7 is a diagram showing various aberrations at the wide-angle end in a close-focusing arrangement according to the first embodiment;

FIG. 8 is a diagram illustrating various aberrations at an intermediate magnification position in a close-focusing arrangement according to the first embodiment;

FIG. 9 is a diagram illustrating various aberrations at a telephoto end in a close-focusing arrangement according to the first embodiment;

FIG. 10 is a lens arrangement diagram at a wide-angle end in a reference focusing arrangement according to a second embodiment.

FIG. 11 is a diagram showing various aberrations at the wide-angle end in a reference focusing arrangement according to a second example.

FIG. 12 is a diagram illustrating various aberrations at an intermediate magnification position in the reference focusing arrangement according to the second example.

FIG. 13 is a diagram showing various aberrations at the telephoto end in a reference in-focus arrangement according to the second embodiment.

FIG. 14 is a diagram showing various aberrations at the wide-angle end in a close-focusing arrangement according to the second embodiment;

FIG. 15 is a diagram illustrating various aberrations at an intermediate magnification position in a close-focusing arrangement according to the second embodiment.

FIG. 16 is a diagram showing various aberrations at the telephoto end in a close-focusing arrangement according to the second embodiment;

FIG. 17 is a lens arrangement diagram at the wide-angle end in the reference in-focus arrangement of the third embodiment.

FIG. 18 is a diagram illustrating various aberrations at the wide-angle end in a reference in-focus arrangement according to the third example.

FIG. 19 is a diagram illustrating various aberrations at an intermediate magnification position in the reference focusing arrangement according to the third example;

FIG. 20 is a diagram showing various aberrations at the telephoto end in a reference in-focus arrangement according to the third embodiment.

FIG. 21 is a diagram illustrating various aberrations at the wide-angle end in a close-focusing configuration according to the third example.

FIG. 22 is a diagram illustrating various aberrations at an intermediate magnification position in a close-focusing arrangement according to the third example;

FIG. 23 is a diagram illustrating various aberrations at the telephoto end in a close-focusing configuration according to the third example;

FIG. 24 is a lens arrangement diagram at the wide-angle end in the reference in-focus arrangement of the fourth embodiment.

FIG. 25 is a diagram illustrating various aberrations at the wide-angle end in the reference in-focus arrangement of the fourth example.

FIG. 26 is a diagram illustrating various aberrations at an intermediate magnification position in the reference focusing arrangement according to the fourth example;

FIG. 27 is a diagram showing various aberrations at the telephoto end in the reference in-focus arrangement of the fourth embodiment.

FIG. 28 is a diagram illustrating various aberrations at the wide-angle end in a close-focusing configuration according to the fourth example;

FIG. 29 is a diagram illustrating various aberrations at an intermediate magnification position in a close-focusing arrangement according to the fourth example;

FIG. 30 is a diagram illustrating various aberrations at the telephoto end in a close-focusing configuration according to a fourth example;

[Explanation of symbols]

G ₁ … first lens group G ₁₁ … first
Front group G ₁₂ ... group after the first lens group G ₂ ... second
Lens group G ₃ ... third lens group G ₄ ... 4
Lens group G ₅ ... diaphragm fifth lens group S ... opening

Claims (8)

[Claims] 1. A zoom optical system that performs zooming by moving the entire system by five or more lens groups and moving three or more zoom lens groups in an optical axis direction in an interdependent manner. Magnifications of two or more variable magnification lens groups in the magnification lens group become almost equal magnification at a specific zooming position, and the first lens group is composed of two or more lower lens groups,
A zoom optical system, wherein focusing is performed by moving one or more lower lens groups of the lower lens groups at different speeds in the optical axis direction. 2. The zoom optical system according to claim 1, wherein said specific zooming position is between a wide-angle end and a telephoto end. 3. The zoom according to claim 1, wherein the sign of the refractive power of each lens group is symmetric between the lens group arranged from the object side and the lens group arranged from the image side. Optical system. 4. A first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens having a negative refractive power. 4. The zoom optical system according to claim 3, comprising a group, and a fifth lens group having a positive refractive power, wherein the second lens group, the third lens group, and the fourth lens group are the zoom lens groups. 5. . 5. A first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens having a negative refractive power. And a fifth lens group having a positive refractive power. The second lens group, the third lens group, the fourth lens group, and the fifth lens group.
The zoom optical system according to claim 3, wherein a lens group is the zoom lens group. 6. The zoom optical system according to claim 1, wherein said first lens group comprises a front group having a positive refractive power and a rear group having a positive refractive power. system. 7. The zoom optical system according to claim 6, wherein an amount of movement of said first lens group during focusing of said front group is larger than an amount of movement of said rear group. 8. The zoom optical system according to claim 6, wherein an amount of movement of said first lens group during focusing of said front group is smaller than an amount of movement of said rear group.