JP4371468B2 - Variable magnification optical system with anti-vibration function - Google Patents

Description

【００７４】
なる式で表している。

【００７５】
【表１】

【００７６】
【発明の効果】
本発明によれば以上のように、変倍光学系の一部を構成する比較的小型軽量のレンズ群を光軸と垂直方向に移動させて、該変倍光学系が振動（傾動）したときの画像のぶれを補正するように構成することにより、装置全体の小型化、機構上の簡素化及び駆動手段の負荷の軽減を図りつつ該レンズ群を偏心させたときの偏心収差発生量を少なく抑え、偏心収差を良好に補正した防振機能を有した変倍光学系を達成することが出来る。
【図面の簡単な説明】
【図１】 本発明における変倍光学系の近軸屈折力配置の概略図
【図２】 本発明における防振系の光学的原理の説明図
【図３】 防振時の光量変化を説明するための図
【図４】 本発明の数値実施例１の広角端のレンズ断面図
【図５】 本発明の数値実施例１の広角端の諸収差図
【図６】 本発明の数値実施例１の望遠端の諸収差図
【図７】 本発明の数値実施例１の望遠端の諸収差図
【図８】 本発明の数値実施例２の広角端の諸収差図
【図９】 本発明の数値実施例２の望遠端の諸収差図
【図１０】 本発明の数値実施例２の望遠端の諸収差図
【図１１】 本発明の数値実施例３の広角端の諸収差図
【図１２】 本発明の数値実施例３の望遠端の諸収差図
【図１３】 本発明の数値実施例３の望遠端の諸収差図
【符号の説明】
Ｌ１ 第１群
Ｌ２ 第２群
Ｌ３ 第３群
Ｌ４ 第４群
ＳＰ 絞り
ＦＰ 固定絞り
ＩＰ 像面
ｄ ｄ線
ｇ ｇ線
ΔＭ メリディオナル像面
ΔＳ サジタル像面[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a variable magnification optical system having an anti-vibration function, and in particular, when the variable magnification optical system vibrates (tilts) by moving a part of the lens group of the variable magnification optical system in a direction perpendicular to the optical axis. A zoom that has a vibration-proof function suitable for video cameras, silver halide photography cameras, electronic still cameras, etc., which stabilizes the captured images by optically correcting the blur of the captured images. The present invention relates to an optical system.
[0002]
[Prior art]
When shooting from a moving object such as a car or aircraft in progress, vibrations are transmitted to the shooting system, causing camera shake and blurring of the shot image.
[0003]
Conventionally, various anti-vibration optical systems have been proposed that have a function of preventing blurring of captured images.
[0004]
For example, in Japanese Patent Application Laid-Open No. 56-21133, a part of optical members are moved in a direction that cancels the vibrational displacement of an image due to vibration in accordance with an output signal from a detecting means for detecting a vibration state in the optical device. Stabilize the image. In JP-A-61-223819, in an imaging system in which a variable apex angle prism is arranged closest to the object side, the apex angle of the variable apex angle prism is changed in accordance with the vibration of the imaging system to stabilize the image. ing.
[0005]
In Japanese Patent Application Laid-Open Nos. 1-116619 and 2-124521, vibration of the photographing system is detected using an acceleration sensor or the like, and a part of the lens group of the photographing system is placed on the optical axis according to a signal obtained at this time. A still image is obtained by vibrating in the vertical direction.
[0006]
In Japanese Patent Laid-Open No. 7-128619, a third lens unit of a variable power optical system having a four-group configuration including lens units having positive, negative, positive, and positive refractive powers in order from the object side has a positive and negative refractive power of 2. The lens is composed of two lens groups, and the positive lens group is vibrated to prevent vibration.
[0007]
In Japanese Patent Laid-Open No. 7-199124, the entire third lens unit of the variable magnification optical system having a four-group configuration including lens units having positive, negative, positive, and positive refractive powers in order from the object side is vibrated to prevent vibration. Yes.
[0008]
On the other hand, in Japanese Patent Laid-Open No. 5-60974, the third lens unit is a negative lens having a meniscus shape and a positive lens in a variable magnification optical system having a four-group structure including positive, negative, positive, and positive lens units in order from the object side. The lens's overall length is shortened as a telephoto type lens.
[0009]
[Problems to be solved by the invention]
In general, a method for obtaining a still image by arranging a vibration-proof optical system in front of a photographing system, vibrating a part of the movable lens group of the vibration-proof optical system to eliminate a blur of a photographed image, There has been a problem that a moving mechanism for moving the movable lens group becomes complicated.
[0010]
In an optical system that performs vibration isolation using a variable apex angle prism, there is a problem in that the amount of decentered chromatic aberration generated increases during image stabilization, particularly on the long focal length side.
[0011]
On the other hand, in an optical system that performs vibration isolation by decentering some lenses of the photographing system in a direction perpendicular to the optical axis, there is an advantage that no extra optical system is required for image stabilization. However, there is a problem that a space for the lens to be moved is required, and that the amount of decentering aberration generated during vibration isolation increases.
[0012]
When the entire third lens group of the variable power optical system having a four-group configuration including positive, negative, positive, and positive refractive power lenses is moved in the direction perpendicular to the optical axis, the third lens group Decentration aberration, especially decentration distortion, occurs when the lens is constructed with a telephoto type of a positive lens and a meniscus negative lens to shorten the overall length. When this is used for a camera such as a video camera, there has been a problem that the deformation of the image at the time of image stabilization is conspicuous.
[0013]
Further, when the zoom ratio is increased, there is a problem that the change in the amount of peripheral light becomes conspicuous during image stabilization.
[0014]
According to the present invention, a relatively small and light lens group constituting a part of a variable magnification optical system is moved in a direction perpendicular to the optical axis so as to correct an image blur when the variable magnification optical system vibrates (tilts). In addition, the lens group for correcting image blur is made appropriate, thereby reducing the overall size of the apparatus, simplifying the mechanism, and reducing the load on the driving unit. An object of the present invention is to provide a variable magnification optical system having an image stabilization function in which decentration aberrations when the lens is decentered are corrected well.
[0015]
[Means for Solving the Problems]
According to the first aspect of the present invention, the first lens unit having a fixed positive refractive power, the second lens unit having a negative refractive power having a zooming function, zooming and focusing in order from the object side upon zooming and focusing. a third lens unit having positive refractive mosquito fixed for the optical axis direction during focusing, variable composed of the fourth lens unit having positive refractive power having a focusing function along with correcting the image plane which varies with zooming A magnification optical system, wherein the third lens group is moved in a direction perpendicular to the optical axis to correct a shake of a captured image when the variable magnification optical system vibrates, and the second lens group is sequentially arranged from the object side. A negative meniscus 21st lens having a strong concave surface on the image side, a negative 22nd lens, a positive 23rd lens, and a negative 24th lens. The third lens group is positive in order from the object side. 31st lens, meniscus negative 32nd lens with strong concave surface facing image side, positive 33rd lens Is configured, the focal length at the telephoto end of the entire system ft, the focal length of the second lens group f2, the focal length of the 24 lens f24, third the most object side lens surface of the variable magnification optical system When the distance to the lens surface closest to the object side of the lens group is LS, and the focal length of the telephoto end of the entire system is ft ,
0.05 <| f2 / ft | <0.07
1.2 <| f24 / f2 | <2.5
0.42 <| LS / ft | <0.59
It satisfies the following conditional expression .
[0016]
The invention of claim 2 is the invention of claim 1, wherein the focal lengths of the thirty-second lens and the third lens group are f32 and f3, respectively .
1.2 <| f32 / f3 | <1.8
It satisfies the following conditional expression.
The invention of claim 3 is characterized by having an aperture stop to be variable in accordance in the invention of claim 1 or 2, the opening diameter at the time of zooming the focal length of the entire system.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic diagram showing a paraxial refractive power arrangement according to the present invention, FIG. 2 is an explanatory diagram of the optical principle of an image stabilization optical system according to the present invention, and FIG. 3 is an explanatory diagram of changes in light quantity during image stabilization in the present invention. . FIG. 4 is a lens cross-sectional view at the wide angle end according to Numerical Embodiment 1 of the present invention.
[0018]
In the figure, L1 is a first group having a positive refractive power, L2 is a second group having a negative refractive power, and L3 is a third group having a positive refractive power. In this embodiment, the third lens unit L3 is moved in the direction perpendicular to the optical axis to correct the shake of the captured image when the variable magnification optical system vibrates (tilts). L4 is a fourth group having a positive refractive power. SP is an aperture stop, which is disposed in front of the third lens unit L3. G is a glass block such as a face plate. IP is the image plane. FP is a flare-cut stop, which is disposed between the third group and the fourth group, and is moved on the optical axis with zooming.
[0019]
In the present embodiment, when zooming from the wide-angle end to the telephoto end, the second group is moved to the image plane side as indicated by the arrow shown in FIG. 1, and the image plane variation caused by zooming is moved by moving the fourth group. It is corrected.
[0020]
In addition, a rear focus type is employed in which focusing is performed by moving the fourth group on the optical axis. The solid curve 4a and the dotted curve 4b of the fourth group shown in the figure show the image plane fluctuations accompanying the zooming from the wide-angle end to the telephoto end when focusing on an object at infinity and an object at close distance, respectively. The movement trajectory for correction is shown. The first group and the third group are fixed during zooming and focusing.
[0021]
In the present embodiment, the fourth group is moved to correct the image plane variation accompanying zooming, and the fourth group is moved to perform focusing. In particular, as shown by the curves 4a and 4b in the figure, the zoom lens is moved so as to have a convex locus toward the object side upon zooming from the wide-angle end to the telephoto end. As a result, the space between the third group and the fourth group is effectively used, and the overall length of the lens is effectively shortened.
[0022]
In the present embodiment, for example, when focusing from an infinitely distant object to a close object at the telephoto end, the fourth group is moved forward as indicated by a straight line 4c in FIG.
[0023]
In the present embodiment, the rear focus method as described above is used in the so-called four-group zoom lens in the conventional so-called four-group zoom lens, and the first group is used for focusing. This effectively prevents an increase in effective lens diameter of one group. By arranging the aperture stop in front of the third lens group, aberration fluctuation due to the movable lens group is reduced, and by shortening the distance between the lens groups in front of the aperture stop, the front lens diameter can be easily reduced. is doing.
[0024]
In the present invention, the third lens unit L3 is moved in the direction perpendicular to the optical axis for image stabilization to correct image blurring when the variable magnification optical system vibrates. As a result, as compared with the conventional image stabilization optical system, image stabilization is performed without newly adding an optical member such as a lens group or a variable apex angle prism for image stabilization.
[0025]
Next, the optical principle of the image stabilization system for correcting the shake of the photographed image by moving the lens group in the direction perpendicular to the optical axis in the variable magnification optical system according to the present invention will be described with reference to FIG.
[0026]
As shown in FIG. 2A, the optical system is composed of three parts, a fixed group Y1, an eccentric group Y2, and a fixed group Y3, and an object point P on the optical axis sufficiently separated from the lens is on the imaging surface IP. Assume that an image is formed at the center as an image point p.
[0027]
Assuming that the entire optical system including the imaging surface IP is instantaneously tilted due to camera shake as shown in FIG. 2B, the object point P is also instantaneously moved to the image point p ′, resulting in a blurred image. .
[0028]
On the other hand, when the eccentric group Y2 is moved in the direction perpendicular to the optical axis, the image point p moves to p ″ as shown in FIG. 2C, and the amount and direction of movement depend on the power arrangement, and the lens group Expressed as eccentric sensitivity.
[0029]
Therefore, the image point p ′ shifted due to the camera shake in FIG. 2B is returned to the original imaging position p by moving the eccentric group Y2 by an appropriate amount in the direction perpendicular to the optical axis. As shown in FIG. 4, camera shake correction, that is, image stabilization is performed.
[0030]
Now, assuming that the shift amount of the shift lens group (eccentric group) Y2 necessary for correcting the optical axis by θ is Δ, the focal length of the entire optical system is f, and the eccentric sensitivity of the shift lens group Y2 is TS, The quantity Δ is Δ = f · tan (θ) / TS
Is given by
[0031]
If the decentering sensitivity TS of the shift lens group Y2 is too large, the movement amount Δ is small and the shift lens group movement amount necessary for image stabilization can be reduced, but it is difficult to control for proper image stabilization. As a result, the remaining correction occurs. In particular, in a video camera or a digital still camera, the image size of an image sensor such as a CCD is smaller than that of a silver halide film, and the focal length with respect to the same angle of view is short. Therefore, the shift amount Δ of the shift lens group for correcting the same angle Becomes smaller.
[0032]
Therefore, if the accuracy of the mechanism (mechanism) is approximately the same, the remaining correction on the screen becomes relatively large.
[0033]
On the other hand, if the eccentricity sensitivity TS is too small, the amount of movement of the shift lens group necessary for control increases, and the driving means such as an actuator for driving the shift lens group also increases.
[0034]
In the present invention, the decentration sensitivity TS of the third lens unit is set to an appropriate value by setting the refractive power arrangement of each lens unit to an appropriate value. An optical system with a small load on the driving means is achieved.
[0035]
Further, when the lens group in such an optical system is shifted in the direction perpendicular to the optical axis to perform image stabilization, an asymmetry of the peripheral light amount distribution occurs with respect to the shift direction. For this reason, during moving image shooting, the direction of camera shake changes with time, so the amount of peripheral light also changes with time, which causes flickering around the screen.
[0036]
This will be described with reference to FIG.
[0037]
When the correction angle of the optical axis is θ, the light beam shake amount H on the lens surface closest to the object side of the optical system is an image HP of the correction lens L3 that can be generated by the optical system closer to the object side than the correction lens (third group) L3. When the distance from the lens surface to the most object side of the optical system is DS, as shown in FIG. 3A, H = DS · tan θ
It becomes.
[0038]
FIGS. 3B, 3C, and 3D show changes in the amount of peripheral light during image stabilization. 3B shows a normal state, FIG. 3C shows a correction state in which the optical system faces downward, and FIG. 3D shows a correction state in which the optical system faces upward. In the corrected state, the amount of light changes because the beam width W of the light beam changes. This amount of change increases as the shake amount H of the central ray passing through the first surface increases.
[0039]
Therefore, in order to reduce the change in the amount of light, the distance DS from the first surface to the third lens unit L3 to be shifted must be shortened to reduce the distance DS.
[0040]
For this purpose, it is preferable to increase the refractive power of the second lens unit to reduce the amount of movement required for zooming of the second lens unit.
[0041]
Therefore, in the present invention, the relationship between the focal length f2 of the second lens group and the focal length ft at the telephoto end of the entire system is expressed as 0.05 <| f2 / ft | <0.07 (1)
Thus, the amount of movement of the second lens group necessary for zooming is reduced.
[0042]
If the refractive power of the second lens unit is increased beyond the lower limit of conditional expression (1), the amount of movement of the second lens unit during zooming decreases, but the Petzval sum increases in the negative direction as a whole, and the field curvature It is not good because it becomes difficult to correct. On the other hand, if the upper limit of (1) is exceeded, the amount of movement of the second lens unit at the time of zooming becomes large, the entire lens system is not miniaturized, and it is disadvantageous with respect to changes in the amount of peripheral light during image stabilization.
[0043]
Under the conditional expression (1), when the zoom ratio is high, such as 20 times or more, it becomes difficult to correct lateral chromatic aberration associated with zooming.
[0044]
In the present invention, the second lens group is composed of a meniscus negative 21st lens having a strong concave surface on the image side from the object side, a negative 22nd lens, a positive 23rd lens, and a negative 24th lens. By reducing the symmetry of the second lens group before and after, the achromatic effect of the principal point is enhanced, and the lateral chromatic aberration is effectively corrected.
[0045]
In the present invention, when the focal length of the 24th lens is f24, 1.2 <| f24 / f2 | <2.5 (2)
It is good to satisfy.
[0046]
Conditional expression (2) is mainly for effectively correcting the magnification color difference. If the upper limit of conditional expression (2) is exceeded and the focal length of the 24th lens becomes too small, the effect of correcting chromatic aberration will be insufficient. Conversely, if the lower limit is exceeded, it becomes difficult to correct distortion at the wide-angle end.
[0047]
Further, in the present invention, in order to reduce the change in the amount of peripheral light during image stabilization, the optical system moves vertically from the lens surface closest to the object side of the imaging system (variable magnification optical system) during image stabilization of the third lens unit. 0.42 <| LS / ft | <0.59 (3) where LS is the distance to the lens surface closest to the object side and ft is the focal length of the telephoto end of the entire system
The following conditional expression is satisfied.
[0048]
If the upper limit of conditional expression (3) is exceeded, the change in the amount of light during image stabilization tends to be noticeable when the magnification is increased. Conversely, in order to exceed the lower limit, it is necessary to increase the refractive power of the second lens group. It is difficult to correct aberration fluctuations during zooming.
[0050]
The variable magnification optical system having the image stabilization function of the present invention is realized by satisfying the above conditions, but in order to achieve good optical performance while further shortening the overall lens length. It is desirable to satisfy at least one of the following conditions.
[0051]
(A-1) The third lens group has a positive 31st lens in order from the object side, and a meniscus negative 32nd lens with a strong concave surface facing the image surface side.
[0052]
(A-2) The third lens group is composed of a positive 31st lens in order from the object side, a meniscus negative 32nd lens with a strong concave surface on the image surface side, and a positive 33rd lens. .
[0053]
By providing a meniscus negative lens having a strong concave surface on the image surface side in the third lens group, the entire third lens group is made into a telephoto configuration, and the principal point interval between the second lens group and the third lens group is shortened. The overall length of the lens has been shortened.
[0054]
When such a meniscus-shaped negative lens is provided, positive distortion occurs on the lens surface, which causes a large amount of eccentric distortion during image stabilization. In order to reduce this decrease, it is only necessary to reduce distortion generated in the entire third lens group.
[0055]
In this embodiment, the positive 33rd lens is arranged on the image plane side of the meniscus negative 32nd lens to maintain a certain telephoto configuration, while correcting the distortion aberration in the third lens group. The occurrence of decentering distortion that occurs when the lens group is shifted to perform vibration isolation is reduced.
[0056]
(A-3) The thirty-first lens has an aspherical shape on both lens surfaces.
[0057]
By providing aspheric surfaces on the lens surfaces on both sides of the 31st lens, spherical aberration is suppressed in the third lens group, and decentration coma that occurs during image stabilization is reduced.
[0058]
(A-4) 1.2 <| f32 / f3 | <1.8 where the focal lengths of the thirty-second lens and the third lens group are f32 and f3, respectively (4)
The following conditional expression is satisfied.
[0059]
Conditional expression (4) is for achieving downsizing of the entire optical system by using the third lens group as a telephoto type.
[0060]
If the refracting power of the 32nd lens in the third lens group becomes stronger beyond the lower limit of conditional expression (4), it is advantageous for shortening the overall length of the lens, but the Petzval sum increases in the negative direction and the field curvature is reduced. It is not good because correction becomes difficult. On the other hand, if the lower limit is exceeded, the total length is not sufficiently shortened.
[0061]
(A-5) Properly setting the sensitivity of the shift group for anti-vibration greatly affects the anti-vibration performance.
[0062]
Therefore, when the focal length of the entire system at the wide angle end is fw and the focal length of the third lens unit is f3, 3.5 <f3 / fw <5.5 (5)
It is good to satisfy the condition. Thereby, the sensitivity of the shift lens group is set to an appropriate value while shortening the total lens length.
[0063]
If the refractive power of the third lens unit is increased beyond the lower limit of the conditional expression (5), the sensitivity of the shift lens unit becomes too high, and if the mechanical accuracy is not strict, the remaining correction at the time of image stabilization will increase. Absent.
[0064]
Conversely, if the refractive power of the third lens group is weakened beyond the upper limit, the shift amount of the third lens group necessary for image stabilization becomes large, and the total lens length becomes large, which is not good.
[0065]
(A-6) In order to correct distortion and astigmatism in the third lens group while maintaining the telephoto configuration of the third lens group, and to maintain good optical performance during image stabilization, the 33 lens When the focal length is f33 and the focal length of the third lens unit is f3, 1.2 <f33 / f3 <2.0 (6)
It is desirable to satisfy the following conditions.
[0066]
If the lower limit of conditional expression (6) is exceeded and the refracting power of the 33rd lens becomes too strong, the telephoto property of the third lens group will not be maintained and the effect of shortening the overall length will be lost. Conversely, when the upper limit is exceeded, correction of distortion and astigmatism in the third lens group becomes insufficient, and the optical performance during image stabilization deteriorates.
[0067]
(A-7) In order to achieve a reduction in the change in the amount of light during image stabilization, the peripheral aperture is relatively increased by reducing the aperture diameter on the telephoto side during zooming to limit the central beam. Is good.
[0068]
(A-8) It is preferable to introduce an aspherical surface to the second lens group in order to correct astigmatism and distortion fluctuation during zooming.
[0069]
(A-9) It is necessary to increase the lens diameter by the amount that the third lens group moves for image stabilization.
[0070]
Accordingly, in order to prevent an excessive on-axis light beam from entering excessively, it is desirable to dispose a fixed stop on the object side or the image plane side of the third lens group. In this embodiment, a fixed stop is disposed between the third lens group and the fourth lens group to effectively use the space and prevent unnecessary light flux from entering.
[0071]
Next, numerical examples of the present invention will be shown. In the numerical examples, Ri is the radius of curvature of the i-th lens surface in order from the object side, Di is the i-th lens thickness and air spacing in order from the object side, and Ni and νi are the i-th lens in order from the object side. The refractive index and Abbe number of the glass. Table 1 shows the relationship between the above-described conditional expressions and numerical examples.
[0072]
The aspheric shape is the X axis in the optical axis direction, the H axis in the direction perpendicular to the optical axis, the light traveling direction is positive, R is the paraxial radius of curvature, and A, B, C, D, and E are the aspheric coefficients. When [0073]
[Expression 1]

[0074]
It is expressed by the following formula.

[0075]
[Table 1]

[0076]
【The invention's effect】
According to the present invention, as described above, when the relatively small and light lens group constituting a part of the variable magnification optical system is moved in the direction perpendicular to the optical axis, the variable magnification optical system vibrates (tilts). The amount of decentering aberration when the lens group is decentered is reduced while reducing the size of the entire device, simplifying the mechanism, and reducing the load on the driving means. Therefore, it is possible to achieve a variable magnification optical system having an image stabilization function that suppresses and corrects decentration aberrations favorably.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a paraxial refractive power arrangement of a variable magnification optical system according to the present invention. FIG. 2 is an explanatory diagram of an optical principle of a vibration isolating system according to the present invention. FIG. 4 is a lens cross-sectional view at the wide-angle end of Numerical Example 1 of the present invention. FIG. 5 is a diagram of various aberrations at the wide-angle end of Numerical Example 1 of the present invention. FIG. 7 is a diagram of various aberrations at the telephoto end of Numerical Example 1 of the present invention. FIG. 8 is a diagram of various aberrations at the wide-angle end of Numerical Example 2 of the present invention. FIG. 10 is a diagram of various aberrations at the telephoto end of Numerical Example 2 according to the present invention. FIG. 11 is a diagram of various aberrations at the wide-angle end according to Numerical Example 3 of the present invention. FIG. 13 is a diagram showing various aberrations at the telephoto end according to Numerical Example 3 of the present invention. FIG. 13 is a diagram showing various aberrations at the telephoto end according to Numerical Example 3 according to the present invention.
L1 1st group L2 2nd group L3 3rd group L4 4th group SP Aperture FP Fixed aperture IP Image plane d d line g g line ΔM Meridional image plane ΔS Sagittal image plane

Claims (3)

A first lens unit having a fixed positive refractive power during zooming and focusing in order from the object side, a second lens unit having a negative refractive power having a zooming function, and an optical axis direction during zooming and focusing A variable power optical system composed of a fourth lens group having a positive refractive power and a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power that corrects an image plane fluctuating by zooming and has a focusing function, The third lens group is moved in a direction perpendicular to the optical axis to correct blurring of a captured image when the variable magnification optical system vibrates, and the second lens group has a strong concave surface on the image plane side in order from the object side. And a negative meniscus 21st lens, a negative 22nd lens, a positive 23rd lens, and a negative 24th lens. The third lens group includes a positive 31st lens and an image plane side in order from the object side. strong concave meniscus shape having a negative 32nd lens having its consists of a positive 33 lens, the entire system The focal length of the far end ft, the focal length of the second lens group f2, the focal length of the 24 lens f24, the most object side of the third lens group from the lens surface closest to the object side variable magnification optical system Where LS is the distance to the lens surface and ft is the focal length of the telephoto end of the entire system .
0.05 <| f2 / ft | <0.07
1.2 <| f24 / f2 | <2.5
0.42 <| LS / ft | <0.59
Variable magnification optical system to have a vibration damping function, characterized by satisfying the conditional expression. When the focal lengths of the thirty-second lens and the third lens group are f32 and f3, respectively .
1.2 <| f32 / f3 | <1.8
Variable magnification optical system to have a vibration reduction function according to claim 1, characterized by satisfying the conditional expression. Variable magnification optical system to have a vibration reduction function according to claim 1 or 2, characterized in that an aperture stop which is variable in accordance with open diameter upon zooming the focal length of the entire system.

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