JPH10260355A - Variable power optical system with vibration-proof function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the variable power optical system with a vibrationproof function which obtain a still image by optically correcting the defocusing of a photographed image when the variable power optical system vibrates. SOLUTION: The variable power optical system has four lens groups, i.e., a 1st group L1 with positive refracting power which is fixed at the time of power variation and focusing, a 2nd group L2 which has a power varying function and negative refracting power, a 3rd group L3 with positive refracting power, and a 4th group L4 which has both a correcting function for correcting an image plane varying owing to power variation and a function for focusing and positive refracting power in order from the object side, and the 3rd group L3 has two lens groups with positive refracting power and also has one lens group FL fixed and the other lens group SL moved at right angles to the optical axis to correct the defocusing of a photographed image when the variable power optical system vibrates.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable power optical system having an image stabilizing function, and more particularly to a variable power optical system by moving a part of a lens group of the variable power optical system in a direction perpendicular to an optical axis. A camera having a vibration reduction function suitable for a photographic camera, a video camera, or the like that stabilizes the captured image by optically correcting a blur of the captured image when the camera vibrates (tilts) to obtain a still image. It relates to a magnification optical system.

[0002]

2. Description of the Related Art When an image is taken from a moving object such as a car or an aircraft in progress, vibration is transmitted to an image taking system, resulting in camera shake and blurring of the taken image.

Conventionally, various anti-vibration optical systems having a function of preventing blurring of a photographed image at this time have been proposed.

For example, in Japanese Patent Publication No. 56-21133, some optical members are moved in a direction to cancel the vibrational displacement of an image due to vibration in response to an output signal from a detecting means for detecting a vibration state in an optical device. This stabilizes the image.

In Japanese Patent Application Laid-Open No. 61-223819, in a photographing system in which a refraction type variable apex angle prism is arranged closest to the subject, the apex angle of the refraction type variable apex angle prism is changed according to the vibration of the imaging system. The image is deflected to stabilize the image.

Japanese Patent Publication No. 56-34847, Japanese Patent Publication No. 5
In JP-A-7-7414, an optical member spatially fixed to vibration is arranged in a part of a photographing system, and a photographed image is deflected by utilizing a prism effect generated by vibration of the optical member. A still image is obtained on the image plane.

[0007] Japanese Patent Application Laid-Open Nos.
In Japanese Patent Application Laid-Open No. -125211, vibration of a photographing system is detected using an acceleration sensor or the like, and according to a signal obtained at this time,
There is also a method of obtaining a still image by vibrating a part of a lens group of a photographing system in a direction orthogonal to an optical axis.

In Japanese Patent Laid-Open Publication No. Hei 7-128619, a first positive refractive power which is fixed during zooming and focusing in order from the object side.
Group, a second group of negative refractive power having a zooming function, an aperture stop,
A zoom lens having four lens groups, a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power having both a correction function and a focusing function for correcting an image plane which fluctuates due to zooming. An optical system, wherein the third unit includes two lens units, a first unit having a negative refractive power and a second unit having a positive refractive power. The third unit is moved in a direction perpendicular to the optical axis. The shake of the captured image when the variable magnification optical system vibrates is corrected.

[0009]

In general, an anti-vibration optical system is disposed in front of a photographing system, and a part of the movable lens group of the anti-vibration optical system is vibrated to eliminate a blur of a photographed image and obtain a still image. The method has a problem that the whole apparatus becomes large and a moving mechanism for moving the movable lens group becomes complicated.

There is also a problem that the amount of eccentric aberration generated when the movable lens group is vibrated increases, and the optical performance is greatly reduced.

An optical system that performs image stabilization using a variable apex angle prism has a problem that the amount of eccentric magnification chromatic aberration increases during image stabilization, especially on the long focal length side (telephoto side).

On the other hand, an optical system that performs image stabilization by decentering some lenses of the photographing system in a direction perpendicular to the optical axis has the advantage that no special optical system is required for image stabilization. However, there is a problem that a space for the lens to be moved is required, and the amount of eccentric aberration generated during image stabilization increases.

In a four-unit variable magnification optical system including four lens units having positive, negative, positive, and positive refractive powers, a method of performing image stabilization by moving the entire third unit in a direction perpendicular to the optical axis. In this case, when the size of an image pickup device such as a CCD is reduced in order to reduce the size of the entire optical system, there is a problem that the accuracy with respect to the eccentric position of the third group for vibration reduction becomes too severe. .

According to the present invention, a relatively small and light lens group constituting a part of a variable power optical system is moved in a direction perpendicular to the optical axis, and an image obtained when the variable power optical system vibrates (tilts) is obtained. By configuring so as to correct the blur, the amount of eccentricity generated when the lens group is decentered is reduced while the size of the entire apparatus is reduced, the mechanism is simplified, and the load on the driving unit is reduced. It is an object of the present invention to provide a variable power optical system having an image stabilizing function that satisfactorily corrects aberration and reduces the sensitivity of the eccentric lens group for image stabilization to reduce an image stabilization correction error.

[0015]

According to the present invention, there is provided a variable power optical system having an image stabilizing function comprising: (1-1) a first lens having a fixed positive refractive power which is fixed during zooming and focusing in order from the object side; Group, a second group having a negative refractive power having a zooming function, a third group having a positive refractive power, and a positive group having both a correcting function and a focusing function for correcting an image plane which fluctuates due to zooming. A variable power optical system having four lens groups of a fourth group of refractive power, wherein the third group has two lens groups of positive refractive power, one of which is fixed. In addition, the other lens group SL is moved in a direction perpendicular to the optical axis to correct blurring of a captured image when the variable power optical system vibrates.

[0016]

FIG. 1 is a schematic view showing a paraxial refractive power arrangement according to the present invention, and FIGS. 2 to 4 are lens sectional views at the wide-angle end of Numerical Examples 1 to 3 of the present invention.

In the drawing, L1 is a first group having a positive refractive power, L2 is a second group having a negative refractive power, L3 is a third group having a positive refractive power, and two lens groups having a positive refractive power. It has SL and FL.

In Numerical Embodiments 1 to 3, the lens group FL is fixed, and the lens group SL is moved in the direction perpendicular to the optical axis to correct the blur of the photographed image when the variable magnification optical system vibrates (tilts). I have.

L4 is a fourth lens unit having a positive refractive power. SP denotes an aperture stop, which is located in front of the third unit L3 or the lens unit FL.
And the lens group SL. G is a glass block such as a face plate. IP is an image plane.

In this embodiment, when zooming from the wide-angle end to the telephoto end, the second lens unit is moved to the image plane side as indicated by an arrow, and the image plane fluctuation due to zooming is corrected by moving the fourth lens unit. ing.

Also, a rear focus system is employed in which the fourth unit is moved on the optical axis to perform focusing. A solid line curve 4a and a dotted line curve 4b of the fourth lens group shown in the same figure show the image plane fluctuation caused by zooming from the wide-angle end to the telephoto end when focusing on an object at infinity and an object at a short distance, respectively. The movement locus for correction is shown. The first and third units are fixed during zooming and focusing.

In the present embodiment, the fourth unit is moved to correct the image plane fluctuation caused by zooming, and the fourth unit is moved for focusing. In particular, as shown by curves 4a and 4b in the same figure, the zoom lens is moved so as to have a convex locus toward the object side when zooming from the wide-angle end to the telephoto end. Thereby, the space between the third and fourth units is effectively used, and the overall length of the lens is effectively reduced.

In this embodiment, for example, when focusing from an object at infinity to an object at a short distance at the telephoto end, the fourth unit is moved forward as indicated by a straight line 4c in FIG.

The zoom lens of the present embodiment employs a zoom system in which a virtual image formed by a combined system of the first and second units is formed on the photosensitive surface by the third and fourth units.

In the present embodiment, the deterioration of the first lens unit due to the eccentricity error is prevented by adopting the rear focus method as described above, as compared with a conventional so-called four-unit zoom lens in which the first lens unit is extended and focused. First while doing
This effectively prevents the effective lens diameter of the group from increasing.

By arranging the aperture stop immediately before the third lens unit or between the lens unit FL and the lens unit SL, aberration fluctuation due to the movable lens unit is reduced, and the distance between the lens units in front of the aperture stop is shortened. As a result, the diameter of the front lens can be easily reduced.

In the first to third numerical embodiments of the present invention, the third
The group L3 is composed of two lens groups SL and FL having a positive refractive power. Of these, the lens group SL is moved in the direction perpendicular to the optical axis for vibration reduction to prevent image blurring when the variable magnification optical system vibrates. Has been corrected. As a result, compared to the conventional anti-vibration optical system, anti-vibration is performed without newly adding an optical member such as a lens group or a variable apex prism for anti-vibration.

Next, the optical principle of the image stabilizing system for correcting the blurring of the photographed image by moving the lens group in the direction perpendicular to the optical axis in the variable power optical system according to the present invention will be described with reference to FIG.

As shown in FIG. 14A, the optical system is composed of three parts, a fixed group Y1, an eccentric group Y2, and a fixed group Y3, and the object point P on the optical axis sufficiently separated from the lens.
Is formed as an image point p at the center of the imaging plane IP.

Now, the entire optical system including the imaging plane IP is shown in FIG.
Assuming that the object point P is instantaneously tilted due to camera shake as shown in FIG. 4B, the object point P also instantaneously moves to the image point p ', resulting in a blurred image.

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. 14C, and the amount and direction of the movement depends on the power arrangement. It is expressed as the eccentric sensitivity of the lens group.

Therefore, the image point p 'shifted by the camera shake in FIG. 14B is returned to the original image forming position p by moving the eccentric group Y2 in the direction perpendicular to the optical axis by an appropriate amount. As shown in (D), camera shake correction, that is, image stabilization is performed.

Now, the amount of movement of the shift lens group (eccentric group) Y2 required to correct the optical axis by θ ° is Δ, the focal length of the entire optical system is f, and the sensitivity of the shift lens group Y2 to eccentricity is TS.
Then, the movement amount Δ is given by the following equation: Δ = f · tan (θ) / TS.

Now, the eccentric sensitivity TS of the shift lens group Y2
Is too large, the amount of movement Δ becomes a small value, and the amount of movement of the shift lens group necessary for image stabilization can be made small. However, it is difficult to perform appropriate image stabilization control, and correction remains.

In particular, in a video camera or a digital still camera, the image size of an image pickup device such as a CCD is smaller than that of a silver halide film, and the focal length for the same angle of view is short, so that a shift lens group for correcting the same angle is used. The shift amount Δ becomes smaller.

Therefore, if the accuracy of the mechanism (mechanism) is almost the same, the remaining correction on the screen will be relatively large.

In a four-unit zoom having a positive, negative, positive and positive refractive power used in a lens for a video camera, the refractive power of the third lens unit is reduced in order to reduce the eccentric sensitivity of the third lens unit. It becomes necessary to reduce the size of the optical system, which is not suitable for miniaturizing the entire optical system.

Accordingly, in the present invention, the refractive power of the shift lens group SL is reduced by dividing the third lens unit into two lens units SL and FL having a positive refractive power.
Also, by reducing the size of the optical system, an optical system with less remaining vibration compensation due to mechanical control errors is achieved.

In the first numerical embodiment of the present invention shown in FIG. 2, the third lens unit L3 is composed of a lens unit SL that shifts in the vertical direction to the optical axis for vibration reduction in order from the object side, and a fixed lens unit FL.
The lens unit SL includes a positive lens having a convex surface facing the object side, a meniscus negative lens having a strong concave surface facing the image surface side, and the lens unit FL includes a positive lens having both lens surfaces convex.

By providing an aspheric lens on at least one surface of the lens group SL and the lens group FL, various aberrations generated in each lens group are reduced, and deterioration of optical performance during image stabilization is suppressed. .

In this embodiment, an aspheric surface is introduced on the most object side of the lens units SL and FL, and the spherical aberration and coma generated in each lens unit are reduced, so that the eccentricity generated during image stabilization is reduced. Aberrations, especially eccentric coma, are satisfactorily corrected. The position of the aspheric surface may be a different lens surface of each lens group.

In order to correct decentered chromatic aberration of magnification and field curvature caused by eccentricity, it is desirable that chromatic aberration is corrected as much as possible by the shift group alone and the Petzval sum is reduced. Therefore, the shift lens group (lens group S
A configuration including at least one negative lens group in L) is effective for correcting chromatic aberration and reducing Petzval sum.

In Numerical Embodiment 2 of the present invention shown in FIG. 3, the third unit is constituted by a fixed lens unit FL from the object side and a lens unit SL shifted vertically to the optical axis for image stabilization. FL is composed of a meniscus positive lens, and a lens unit S
L is composed of a positive lens having both convex surfaces and a negative meniscus lens having a strong concave surface facing the object side. An aspherical surface is introduced on the most object side of the lens group SL, and the lens group SL
Spherical aberration and coma aberration are reduced to suppress the occurrence of eccentric coma that occurs during image stabilization.

In the present embodiment, by disposing the negative lens closest to the image plane side of the third lens unit, the entire third lens unit is made closer to a telephoto type, and the entire lens length of the entire optical system is shortened. .

In Numerical Embodiment 3 of the present invention shown in FIG. 4, the third unit is composed of a fixed lens unit FL from the object side and a lens unit SL shifted for image stabilization.
By disposing the aperture stop SP between the first lens and the second lens, the position at which an off-axis ray passing through the lens group SL passes is lowered, and the fluctuation of the field curvature and distortion due to image stabilization is reduced. In addition, an aspheric surface is provided on the most object side of the lens unit SL and the lens unit FL to correct various aberrations well.

The variable power optical system having the image stabilizing function of the present invention is realized by satisfying the above conditions. However, in order to further shorten the overall length of the lens while maintaining good optical performance. It is desirable that at least one of the following conditions be satisfied.

(A-1) The Third Group and the Lens Group SL
Where f3 and fSL are respectively set as f3 and fSL, the following condition is satisfied: 1.3 <fSL / f3 <2.0 (1)

Conditional expression (1) relates to the refractive power arrangement of the two lens units constituting the third unit. If the refractive power of the lens group SL is increased beyond the lower limit value of the conditional expression (1), the eccentricity sensitivity is also increased, and as described above, the remaining amount of correction for image stabilization due to the influence of the mechanical error increases. . Conversely, if the refractive power of the lens group SL is reduced beyond the upper limit value, the amount of movement of the lens group SL required during image stabilization becomes too large, and members such as an actuator for driving the lens group SL become large, which is not good. .

(A-2) The focal length of the second lens unit is f2,
When the focal lengths at the wide-angle end and the telephoto end of the entire system are fW and fT, respectively,

[0050]

(Equation 2) Satisfying the following conditions.

If the refractive power of the second lens unit becomes too strong beyond the lower limit value of the conditional expression (2), it is advantageous for shortening the overall length of the lens, but it is necessary to correct the variation of the field curvature and distortion over the entire zoom range. Is not good because it becomes difficult. If the refractive power of the second lens unit becomes too weak beyond the upper limit of conditional expression (2), the amount of movement of the second lens unit required for zooming becomes too large, which is not good.

If the refractive power of the third lens unit is increased beyond the lower limit of conditional expression (3), it is advantageous for shortening the overall length of the lens, but it is not preferable because it becomes difficult to secure the back focus.
If the refractive power of the third lens unit is weakened beyond the upper limit value of the conditional expression (3), it becomes difficult to shorten the entire length of the lens.

(A-3) The convex surface closest to the object side of the SL lens group is an aspherical surface having a shape such that the positive refractive power becomes weaker from the lens center to the lens periphery.

Next, numerical examples of the present invention will be described. 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 from the object side, and Ni and νi are the i-th lens surfaces in order from the object side. The refractive index and Abbe number of glass.

Table 1 shows the relationship between the above-described conditional expressions and various numerical values in the numerical examples.

The aspherical shape has an X axis in the optical axis direction, an H axis in a direction perpendicular to the optical axis, a positive traveling direction of light, and R as a paraxial radius of curvature.
When A, B, C, D, and E are aspheric coefficients, respectively,

[0057]

(Equation 3) It is represented by the following equation. "E-0X" means 10- ^X . (Numerical Example 1) F = 1 to 9.75 FNO = 1.85 to 2.43 2ω = 60.5 ° to 6.8 ° R 1 = 13.432 D 1 = 0.18 N 1 = 1.84666 ν 1 = 23.8 R 2 = 4.279 D 2 = 1.21 N 2 = 1.71299 ν 2 = 53.8 R 3 = -16.292 D 3 = 0.04 R 4 = 3.174 D 4 = 0.60 N 3 = 1.77249 ν 3 = 49.6 R 5 = 6.374 D 5 = Variable R 6 = 4.590 D 6 = 0.14 N 4 = 1.88299 ν 4 = 40.8 R 7 = 1.088 D 7 = 0.56 R 8 = -1.302 D 8 = 0.12 N 5 = 1.71700 ν 5 = 47.9 R 9 = 1.618 D 9 = 0.44 N 6 = 1.84666 ν 6 = 23.8 R10 = -7.312 D10 = Variable R11 = Aperture D11 = 0.31 R12 = 1.614 Aspherical surface D12 = 0.45 N 7 = 1.58312 ν 7 = 59.4 R13 = 23.575 D13 = 0.02 R14 = 2.006 D14 = 0.14 N 8 = 1.84666 ν 8 = 23.8 R15 = 1.372 D15 = 0.43 R16 = 5.106 aspheric surface D16 = 0.26 N 9 = 1.58312 ν 9 = 59.4 R17 = -21.356 D17 = variable R18 = 2.762 aspheric surface D18 = 0.64 N10 = 1.58312 ν10 = 59.4 R19 = -1.484 D19 = 0.12 N11 = 1.84666 ν11 = 23.8 R20 = -2.909 D20 = 0.71 R21 = ∞ D21 = 0.88 N12 = 1.51633 ν12 = 64.1 R22 = ∞ Aspherical coefficient R12 K = -1.847e-02 B = -2.316e-02 C = 1.045e-03 D = -4.875 e-03 E = 0 R16 K = 9.862e + 00 B = -1.198e-02 C = -1.155e-03 D = -2.915e-03 E = 5.173e-03 R18 K = -1.754 e + 00 B = 6.556e-03 C = -5.764e-03 D = 1.252e-02 E = -3.690e-03

[0058]

[Table 1] (Numerical Example 2) F = 1 to 9.75 FNO = 1.85 to 2.43 2ω = 60.5 ° to 6.8 ° R 1 = 13.123 D 1 = 0.18 N 1 = 1.84666 ν 1 = 23.8 R 2 = 4.332 D 2 = 1.21 N 2 = 1.71299 ν 2 = 53.8 R 3 = -15.563 D 3 = 0.04 R 4 = 3.205 D 4 = 0.60 N 3 = 1.77249 ν 3 = 49.6 R 5 = 6.250 D 5 = variable R 6 = 4.973 D 6 = 0.14 N 4 = 1.88299 ν 4 = 40.8 R 7 = 1.098 D 7 = 0.53 R 8 = -1.293 D 8 = 0.12 N 5 = 1.71700 ν 5 = 47.9 R 9 = 1.554 D 9 = 0.44 N 6 = 1.84666 ν 6 = 23.8 R10 = -7.532 D10 = Variable R11 = Aperture D11 = 0.31 R12 = 2.768 Aspherical surface D12 = 0.33 N 7 = 1.66910 ν 7 = 55.4 R13 = 4.909 D13 = 0.24 R14 = 1.673 Aspherical surface D14 = 0.45 N 8 = 1.58312 ν 8 = 59.4 R15 = -17.228 D15 = 0.02 R16 = 2.003 D16 = 0.14 N 9 = 1.84666 ν 9 = 23.8 R17 = 1.290 D17 = Variable R18 = 2.427 Aspherical surface D18 = 0.64 N10 = 1.58312 ν10 = 59.4 R19 = -1.533 D19 = 0.12 N11 = 1.84666 ν11 = 23.8 R20 = -3.220 D20 = 0.71 R21 = ∞ D21 = 0.88 N12 = 1.51633 ν12 = 64.1 R22 = ∞ Aspherical coefficient R12 K = -6.606e + 00 B = 2.935e-02 C = -9.942e-03 D = 3.892e -03 E = -2.100e-03 R14 K = -3.167e-01 B = -1.124e-02 C = -4.208e-03 D = 2.283e-03 E = 0 R18 K = -2.585e +00 B = 1.786e-02 C = -1.134e-02 D = 1.482e-02 E = -2.606e-03

[0059]

[Table 2] (Numerical Example 3) F = 1 to 9.75 FNO = 1.85 to 2.25 2ω = 60.5 ° to 6.8 ° R 1 = 13.453 D 1 = 0.18 N 1 = 1.84666 ν 1 = 23.8 R 2 = 4.446 D 2 = 1.29 N 2 = 1.69679 ν 2 = 55.5 R 3 = -13.988 D 3 = 0.04 R 4 = 3.223 D 4 = 0.60 N 3 = 1.77249 ν 3 = 49.6 R 5 = 6.152 D 5 = Variable R 6 = 5.790 D 6 = 0.14 N 4 = 1.88299 ν 4 = 40.8 R 7 = 1.116 D 7 = 0.53 R 8 = -1.274 D 8 = 0.12 N 5 = 1.69350 ν 5 = 53.2 R 9 = 1.679 D 9 = 0.44 N 6 = 1.84666 ν 6 = 23.8 R10 = -8.414 D10 = Variable R11 = 3.966 aspheric surface D11 = 0.29 N 7 = 1.66910 ν 7 = 55.4 R12 = 23.810 D12 = 0.24 R13 = aperture D13 = 0.33 R14 = 1.637 aspheric surface D14 = 0.45 N 8 = 1.58312 ν 8 = 59.4 R15 = -14.062 D15 = 0.02 R16 = 2.342 D16 = 0.14 N 9 = 1.84666 ν 9 = 23.8 R17 = 1.365 D17 = Variable R18 = 2.331 Aspherical surface D18 = 0.60 N10 = 1.58312 ν10 = 59.4 R19 = -1.690 D19 = 0.12 N11 = 1.84666 ν11 = 23.8 R20 = -3.598 D20 = 0.71 R21 = ∞ D21 = 0.88 N12 = 1.51633 ν12 = 64.1 R22 = ∞ Aspherical coefficient R11 K = -1.316e + 01 B = 2.207e-02 C = -9.331e-03 D = -1.570 e-03 E = 2.801e-03 R14 K = -4.979e-01 B = -1.037e-02 C = 1.652e-04 D = 5.116e-04 E = 0 R18 K = -1.937 e + 00 B = 1.339e-02 C = -1.140e-02 D = 1.230e-02 E = -2.217e-04

[0060]

[Table 3]

[0061]

[Table 4]

[0062]

As described above, according to the present invention, by moving the relatively small and light lens group constituting a part of the variable power optical system in the direction perpendicular to the optical axis, the variable power optical system is vibrated. When the lens group is decentered while reducing the overall size of the apparatus, simplifying the mechanism, and reducing the load on the driving means, the configuration is such that image blurring caused by (tilting) is corrected. A variable power optical system with an anti-vibration function that minimizes the amount of eccentricity, satisfactorily corrects eccentric aberrations, and reduces the sensitivity of the eccentric lens group for anti-vibration to reduce the correction error of anti-vibration. Can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a paraxial refractive power arrangement of a variable power optical system according to the present invention.

FIG. 2 is a sectional view of a lens at a wide-angle end according to Numerical Embodiment 1 of the present invention.

FIG. 3 is a sectional view of a lens at a wide-angle end according to a second numerical embodiment of the present invention;

FIG. 4 is a sectional view of a lens at a wide-angle end according to a third numerical embodiment of the present invention.

FIG. 5 is a diagram illustrating various aberrations at a wide-angle end according to Numerical Embodiment 1 of the present invention.

FIG. 6 is a diagram illustrating various aberrations at the telephoto end according to Numerical Embodiment 1 of the present invention.

FIG. 7 is a diagram showing various aberrations at the telephoto end according to Numerical Embodiment 1 of the present invention.

FIG. 8 is a diagram illustrating various aberrations at the wide-angle end according to Numerical Example 2 of the present invention.

FIG. 9 is a diagram showing various aberrations at the telephoto end according to Numerical Example 2 of the present invention.

FIG. 10 is a diagram showing various aberrations at the telephoto end according to Numerical Example 2 of the present invention;

FIG. 11 is a diagram illustrating various aberrations at a wide angle end according to Numerical Example 3 of the present invention.

FIG. 12 is a diagram illustrating various aberrations at the telephoto end according to Numerical Example 3 of the present invention.

FIG. 13 is a diagram illustrating various aberrations at the telephoto end according to Numerical Example 3 of the present invention.

FIG. 14 is an explanatory diagram of the optical principle of the vibration isolation system according to the present invention.

[Explanation of symbols]

 L1 First group L2 Second group L3 Third group L4 Fourth group SL Lens group FL Lens group SP Aperture IP Image plane d d line gg line ΔM Meridional image plane ΔS Sagittal image plane

Claims (5)

[Claims] 1. A first lens unit having a fixed positive refractive power, a second lens unit having a negative refractive power having a zooming function, and a third lens unit having a positive refractive power during zooming and focusing in order from the object side. A variable power optical system having four lens units of a fourth lens unit having a positive refractive power and having both a correction function and a focusing function of correcting an image plane that fluctuates due to zooming; The third group has two lens groups having a positive refractive power. Of these, one lens group FL is fixed, and the other lens group SL is moved in a direction perpendicular to the optical axis, so that the variable power optical system vibrates. A variable power optical system having an image stabilizing function characterized by correcting blurring of a captured image at the time. 2. The condition that 1.3 <fSL / f3 <2.0 is satisfied when the focal lengths of the third group and the lens group SL are f3 and fSL, respectively. Variable magnification optical system with anti-vibration function. 3. The SL lens group includes a positive lens having a convex surface facing the object side and a meniscus negative lens having a convex surface facing the object side. The FL lens group includes a positive lens having both lens surfaces convex. 3. The variable power optical system according to claim 1, wherein the variable power optical system has an image stabilizing function. 4. The lens system according to claim 2, wherein the convex surface closest to the object side of the SL lens group is an aspheric surface having a shape in which positive refractive power becomes weaker from the lens center toward the lens periphery.
Or a variable power optical system having an anti-vibration function of 3. 5. When the focal length of the second lens unit is f2, and the focal lengths at the wide-angle end and the telephoto end of the entire system are fW and fT, respectively: 5. A variable power optical system having an anti-vibration function according to claim 2, wherein the following condition is satisfied.