JPH10260356A - 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 obtains a still image by optically correcting the defocusing of a photographed image when the variable power optical system vibrates. SOLUTION: This variable power optical system has four lens groups, i.e., a 1st group L1 with positive refracting power 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 an image plane varying owing to the power variation and a focusing function and also has positive refracting power in order from the object side, and the 3rd group L3 has a meniscus negative lens L3N having its concave surface on the imageplane side and one aspherical surface, and is moved at right angles to the optical axis to correct the defocusing of the 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.

[0008] In Japanese Patent Application Laid-Open No. Hei 7-128619,
A first group of positive refractive power fixed at the time of zooming and focusing in order from the object side, a second group of negative refractive power having a zooming function, an aperture stop, a third group of positive refractive power, and A variable power optical system having four lens units of a fourth group having a positive refractive power and having both a correction function of correcting an image plane that varies due to zooming and a focusing function, wherein the third group is Is composed of two lens units, a 31st lens unit having a negative refractive power and a 32nd lens unit having a positive refractive power. When the 32nd lens unit is moved in a direction perpendicular to the optical axis and the zoom optical system vibrates, The camera shake is corrected.

In Japanese Patent Application Laid-Open No. 7-199124,
In a variable power optical system having a four-unit configuration including four lens units having negative, positive, and positive refractive power, the entire third unit is vibrated in a direction perpendicular to the optical axis to perform image stabilization.

On the other hand, JP-A-5-60974 discloses that
In a four-unit variable magnification optical system including four lens units having positive, negative, positive, and positive refractive powers, a third unit includes a telephoto type of a positive lens and a meniscus-shaped negative lens, and the entire length of the lens is reduced. We are trying to shorten it.

[0011]

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 chromatic aberration of eccentric magnification 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 the above-described four-unit variable magnification optical system including the four lens units having the positive, negative, positive and positive refractive powers, the entire third unit is moved in a direction perpendicular to the optical axis to reduce vibration. If this is done, when the third lens unit is made up of a telephoto type of a positive lens and a meniscus negative lens for shortening the overall length of the lens, a large amount of eccentric aberration, especially eccentric distortion, is generated. If you use this for video shooting such as a video camera,
There has been a problem that the image deformation during image stabilization is noticeable.

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. When correcting blur, when the lens group is decentered while appropriately reducing the load on the driving unit by reducing the load on the drive unit by reducing the size of the entire apparatus, simplifying the mechanism, and appropriately configuring the lens configuration of the lens group. It is an object of the present invention to provide a variable power optical system having an image stabilizing function in which the amount of occurrence of eccentricity is suppressed to a small value and eccentric aberration is corrected well.

[0017]

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 including four lens units of a fourth unit having a refractive power, wherein the third unit includes a negative meniscus lens L3N having a concave surface facing the image surface side and one aspheric surface, It is characterized in that the third group is moved in a direction perpendicular to the optical axis to correct blurring of a photographed image when the variable magnification optical system vibrates.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view showing a paraxial refractive power arrangement of Numerical Embodiments 1 to 3 of the present invention to be described later, and FIGS. It is a lens sectional view of.

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 blur of the photographed image when the variable magnification optical system vibrates (tilts).

L4 is a fourth lens unit having a positive refractive power. SP denotes an aperture stop, which is arranged in front of the third lens unit L3. 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 caused by zooming is corrected by moving the fourth lens unit. ing.

Also, a rear focus type is adopted 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 lens unit is moved to correct the image plane fluctuation accompanying zooming, and the fourth lens unit is moved to perform 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 shown by a straight line 4c in FIG.

The zoom lens according to 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 rear focus method is used to prevent the performance degradation due to the eccentric error of the first group, as compared with the conventional so-called four-group zoom lens in which the first group 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, aberration fluctuations caused by the movable lens unit can be reduced, and the distance between the lens units in front of the aperture stop can be reduced to reduce the diameter of the front lens. Achieved easily.

In the first to third numerical embodiments of the present invention, the third
The group L3 is moved in the direction perpendicular to the optical axis to correct image blurring when the variable magnification optical system vibrates. 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 an image stabilizing system for correcting blurring of a photographed image by moving a lens group in a direction perpendicular to the optical axis in a 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 an object point P on the optical axis sufficiently far 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.

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

Now, the amount of movement (shift amount) of the shift lens group (eccentric group) required to correct 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 the TS, the movement amount Δ is given by the following equation: Δ = f · tan (θ) / TS.

If the eccentricity sensitivity TS of the shift lens group is too large, the moving amount Δ becomes small, and the moving amount of the shift lens group necessary for image stabilization can be reduced. Becomes difficult, and the 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 shifted. The quantity 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.

On the other hand, if the eccentric sensitivity TS is too small, the amount of movement of the shift lens group necessary for control becomes large, and the driving means such as an actuator for driving the shift lens group also becomes large.

In the present invention, by setting the refractive power arrangement of each lens group to an appropriate value, the eccentricity sensitivity TS of the third group is set to an appropriate value, and there is little remaining vibration compensation due to mechanical control errors. An optical system in which the load of driving means such as an actuator is small is achieved.

In the present embodiment, the third lens unit includes, in order from the object side, a positive lens L31 having both convex lens surfaces, a negative meniscus lens L32 having a strong concave surface facing the image surface, and a meniscus lens having a convex surface facing the object side surface. And the positive lens L33.

In numerical embodiments 1 and 2 shown in FIGS. 2 and 3,
The object-side lens surface of the positive lens L31 and the image surface-side lens surface of the positive lens L33 are aspheric.

By providing a meniscus-shaped negative lens having a concave surface facing the image surface side in the third lens unit, the entire third lens unit has a telephoto configuration, and the distance between the principal points of the second lens unit and the third lens unit is reduced.
The overall length of the lens has been shortened.

When such a meniscus negative lens is provided, positive distortion occurs on the lens surface.

Now, suppose that the entire third lens unit has a positive distortion. It is assumed that the entire third lens unit is eccentric upward as shown in FIG. At this time, the height at which the off-axis ray coming to the point S1 passes through the third lens unit decreases, and the positive distortion decreases. Conversely, a light beam coming to the side of the point S2 increases the positive distortion. Therefore, a quadrilateral object is shown in FIG.
The shape is deformed as shown by the solid line in FIG.

Conversely, when the third lens unit moves downward, FIG.
Since the image is deformed into a shape as indicated by the dotted line in (B), when vibration is applied, the image is deformed in accordance with the vibration, and the viewer is particularly uncomfortable with a moving image. To reduce this decrease a third
What is necessary is just to reduce the distortion generated in the entire group.

In the first and second numerical embodiments, the positive lens L33 is disposed on the image side of the negative meniscus lens L32, and an aspherical surface is provided on the image side. To correct the distortion, and reduce the occurrence of the eccentric distortion generated when performing the image stabilization by shifting the third lens unit.

In Numerical Examples 1 and 2, the aspherical surface is provided on the lens surface of the lens L31 on the object side, so that spherical aberration is suppressed in the third lens unit and eccentric coma generated during image stabilization is reduced. .

In Numerical Example 3 shown in FIG. 4, the aspheric surface is provided on the image surface side of the meniscus negative lens L32 to correct the distortion in the third lens unit while maintaining the telephoto configuration. In addition, the occurrence of eccentric distortion occurring when the third group is shifted to perform image stabilization is reduced. In addition, an aspheric surface is introduced into the lens surface on the object side of the lens L31 to reduce spherical aberration and coma aberration in the third lens unit, thereby suppressing occurrence of eccentric coma aberration generated during image stabilization.

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 reduce the overall length of the lens and achieve good optical performance. Preferably satisfies at least one of the following conditions.

(A-1) The negative lens L3N and the third lens L3N
Assuming that the focal lengths of the groups are f3N and f3, respectively, the following condition is satisfied: 1.0 <| f3N / f3 | <1.6 (1)

Conditional expression (1) is used to reduce the size of the entire optical system by using the third lens unit as a telephoto type. Increasing the refractive power of the negative lens in the third lens group beyond the lower limit of conditional expression (1) is advantageous for shortening the overall length of the lens, but the Petzval sum increases negatively and the correction of the field curvature becomes difficult. Not good because it becomes difficult. Conversely, if the value exceeds the upper limit, the reduction of the overall length of the lens becomes insufficient.

(A-2) The focal length of the third lens unit is f3,
Assuming that the focal length at the wide angle end of the entire system is fW, the following condition is satisfied: 2.3 <f3 / fW <4.0 (2)

Conditional expression (2) is intended to appropriately set the sensitivity of the shift lens group for image stabilization and to maintain good image stabilization performance while shortening the overall length of the lens. Conditional expression
If the refractive power of the third lens group is increased beyond the lower limit of (2), the sensitivity of the shift lens group becomes too large, and if the mechanical precision is not strict, the correction remaining during image stabilization increases, which is not good. . Conversely, if the refractive power of the third lens unit is weakened beyond the upper limit, the amount of shift of the third lens unit required for image stabilization is increased, and the overall length of the lens is undesirably increased.

(A-3) 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,

[0056]

(Equation 3) 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 (3), it is advantageous for shortening the entire length of the lens. However, the variation of the field curvature and distortion over the entire zoom range is corrected. It 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 (3), the amount of movement of the second lens unit required for zooming becomes too large.

Further, in the image stabilizing optical system of the present invention, in order to maintain a sufficient correction angle for image stabilization and maintain optical performance during image stabilization, the lenses of the third lens unit and the fourth lens unit are required. When the paraxial lateral magnification at the telephoto end of the group is β3t and β4t, respectively, and the maximum amount of movement of the third lens group during vibration reduction is Dm

[0059]

(Equation 4) It is better to satisfy the following conditions.

If the lower limit of conditional expression (4) is exceeded, the correction angle of the image stabilization becomes small, and the image stabilization effect becomes small. On the other hand, if the upper limit is exceeded, deterioration of optical performance and change in light amount during vibration proof are conspicuous, which is not good.

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-mentioned conditional expressions and various numerical values in the numerical examples.

The aspheric surface 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, R is a paraxial radius of curvature,
When A, B, C, D, and E are aspheric coefficients, respectively,

[0064]

(Equation 5) It is represented by the following equation. "E-0X" means 10- ^X . (Numerical Example 1) F = 1 to 9.75 FNO = 1.85 to 2.46 2ω = 60.5 ° to 6.8 ° R 1 = 12.404 D 1 = 0.18 N 1 = 1.84666 ν 1 = 23.8 R 2 = 4.052 D 2 = 1.21 N 2 = 1.71299 ν 2 = 53.8 R 3 = -17.341 D 3 = 0.04 R 4 = 3.150 D 4 = 0.60 N 3 = 1.77249 ν 3 = 49.6 R 5 = 6.789 D 5 = variable R 6 = 4.605 D 6 = 0.14 N 4 = 1.88299 ν 4 = 40.8 R 7 = 1.042 D 7 = 0.54 R 8 = -1.239 D 8 = 0.12 N 5 = 1.71299 ν 5 = 53.8 R 9 = 1.474 D 9 = 0.44 N 6 = 1.84666 ν 6 = 23.8 R10 = -10.154 D10 = Variable R11 = Aperture D11 = 0.33 R12 = 1.589 Aspherical surface D12 = 0.86 N 7 = 1.66910 ν 7 = 55.4 R13 = -20.729 D13 = 0.04 R14 = 2.119 D14 = 0.14 N 8 = 1.84666 ν 8 = 23.8 R15 = 1.189 D15 = 0.21 R16 = 2.082 D16 = 0.40 N 9 = 1.58312 ν 9 = 59.4 R17 = 4.282 Aspheric surface D17 = Variable R18 = 2.376 Aspheric surface D18 = 0.64 N10 = 1.58312 ν10 = 59.4 R19 = -1.744 D19 = 0.12 N11 = 1.84666 ν11 = 23.8 R20 = -3.655 D20 = 0.71 R21 = ∞ D21 = 0.88 N12 = 1.51633 ν12 = 64.1 R22 = ∞ Aspherical coefficient R12 K = -3.068e + 00 B = 6.133e-02 C = -1.048e-02 D = -4.205 e-03 E = 2.843e-03 R17 K = -5.948e + 01 B = 7.172e-02 C = -5.099e-02 D = 5.965e-03 E = 0 R18 K = -4.437 e + 00 B = 3.052e-02 C = -6.496e-03 D = 9.474e-03 E = -1.915e-03

[0065]

[Table 1] (Numerical Example 2) F = 1 to 9.77 FNO = 1.85 to 2.57 2ω = 59.4 ° to 6.7 ° R 1 = 12.041 D 1 = 0.17 N 1 = 1.80518 ν 1 = 25.4 R 2 = 3.662 D 2 = 1.19 N 2 = 1.69679 ν 2 = 55.5 R 3 = -15.896 D 3 = 0.04 R 4 = 2.995 D 4 = 0.59 N 3 = 1.77249 ν 3 = 49.6 R 5 = 6.384 D 5 = Variable R 6 = 4.213 D 6 = 0.14 N 4 = 1.88299 ν 4 = 40.8 R 7 = 0.999 D 7 = 0.52 R 8 = -1.184 D 8 = 0.12 N 5 = 1.69679 ν 5 = 55.5 R 9 = 1.425 D 9 = 0.42 N 6 = 1.84666 ν 6 = 23.8 R10 = -14.838 D10 = Variable R11 = Aperture D11 = 0.33 R12 = 1.485 Aspherical surface D12 = 0.70 N 7 = 1.66910 ν 7 = 55.4 R13 = -15.967 D13 = 0.03 R14 = 2.006 D14 = 0.14 N 8 = 1.84666 ν 8 = 23.8 R15 = 1.169 D15 = 0.24 R16 = 2.449 D16 = 0.35 N 9 = 1.58312 ν 9 = 59.4 R17 = 4.140 Aspheric D17 = Variable R18 = 2.346 Aspheric D18 = 0.63 N10 = 1.58913 ν10 = 61.2 R19 = -1.584 D19 = 0.12 N11 = 1.84666 ν11 = 23.8 R20 = -3.394 D20 = 0.70 R21 = ∞ D21 = 0.86 N12 = 1.51633 ν12 = 64.1 R22 = ∞ Aspherical coefficient R12 K = -2.933e + 00 B = 7.010e-02 C = -1.269e-02 D = -4.760 e-03 E = 3.375e-03 R17 K = -4.936e + 01 B = 7.490e-02 C = -3.698e-02 D = 7.116e-03 E = 0 R18 K = -4.241 e + 00 B = 3.389e-02 C = -9.367e-03 D = 1.652e-02 E = -5.909e-03

[0066]

[Table 2] (Numerical Example 3) F = 1 to 9.76 FNO = 1.85 to 2.44 2ω = 60.5 ° to 6.8 ° R 1 = 13.534 D 1 = 0.18 N 1 = 1.84666 ν 1 = 23.8 R 2 = 4.112 D 2 = 1.21 N 2 = 1.71299 ν 2 = 53.8 R 3 = -16.831 D 3 = 0.04 R 4 = 3.173 D 4 = 0.60 N 3 = 1.77249 ν 3 = 49.6 R 5 = 6.780 D 5 = Variable R 6 = 4.370 D 6 = 0.14 N 4 = 1.83480 ν 4 = 42.7 R 7 = 1.013 D 7 = 0.57 R 8 = -1.234 D 8 = 0.12 N 5 = 1.69679 ν 5 = 55.5 R 9 = 1.525 D 9 = 0.44 N 6 = 1.84666 ν 6 = 23.8 R10 = -11.259 D10 = Variable R11 = Aperture D11 = 0.33 R12 = 1.649 Aspherical surface D12 = 0.76 N 7 = 1.67790 ν 7 = 55.3 R13 = -13.084 D13 = 0.04 R14 = 2.280 D14 = 0.14 N 8 = 1.84666 ν 8 = 23.8 R15 = 1.243 Aspherical surface D15 = 0.18 R16 = 2.016 D16 = 0.40 N 9 = 1.58312 ν 9 = 59.4 R17 = 4.117 D17 = Variable R18 = 2.391 Aspherical surface D18 = 0.64 N10 = 1.58913 ν10 = 61.2 R19 = -1.763 D19 = 0.12 N11 = 1.84666 ν11 = 23.8 R20 = -3.732 D20 = 0.60 R21 = ∞ D21 = 0.88 N12 = 1.51633 ν12 = 64.1 R22 = ∞ Aspherical coefficient R12 K = -3.240e + 00 B = 6.578e-02 C = -1.729e-02 D = -8.774 e-04 E = 1.601e-03 R15 K = 1.204e-01 B = -2.688e-03 C = 1.003e-02 D = -2.891e-02 E = 0 R18 K = -3.069 e + 00 B = 2.134e-02 C = -4.778e-03 D = 1.123e-02 E = -4.209e-03

[0067]

[Table 3]

[0068]

[Table 4]

[0069]

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 correcting image blurring caused by (tilting), by appropriately configuring the lens configuration of the lens group, the overall size of the apparatus can be reduced,
A vari-focal optical system having a vibration reduction function in which the amount of eccentricity generated when the lens group is decentered is reduced while the eccentricity of the lens group is reduced while simplification of the mechanism and reduction of the load on the driving means is achieved. 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 lens unit L2 Second lens unit L3 Third lens unit L4 Fourth lens unit SP Aperture IP image plane d d line g g line ΔM Meridional image plane ΔS Sagittal image plane

Claims (8)

[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 unit has a meniscus-shaped negative lens L3N having a concave surface facing the image surface side and one aspheric surface. When the third unit is moved in a direction perpendicular to the optical axis and the variable power optical system vibrates. A variable power optical system having an image stabilizing function characterized by correcting blurring of a photographed image. 2. The condition that 1.0 <| f3N / f3 | <1.6 is satisfied, where f3N and f3 are the focal lengths of the negative lens L3N and the third lens unit, respectively. Item 6. A variable power optical system having the image stabilizing function according to item 1. 3. A variable power optical system having an anti-vibration function according to claim 1, wherein a lens having an aspherical surface is disposed on said negative lens L3N or a lens disposed on the image side thereof. . 4. The third lens group includes a positive lens L31 having a strong convex surface on the object side, a negative meniscus lens L32 having a concave surface facing the image side, and a positive meniscus lens L33 having a convex surface facing the object side. 2. The device according to claim 1, wherein
Or a variable power optical system having an anti-vibration function. 5. The positive lens L31 or the positive lens L33.
5. A variable power optical system having an image stabilizing function according to claim 4, wherein at least one of the lens surfaces comprises an aspherical surface. 6. The condition that 2.3 <f3 / fW <4.0 is satisfied, where f3 is the focal length of the third lens unit and fW is the focal length at the wide-angle end of the entire system. 3. A variable power optical system having the image stabilizing function according to claim 1. 7. 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. 7. A variable power optical system having an image stabilizing function according to claim 1, wherein the following conditions are satisfied. 8. When the paraxial lateral magnifications of the third lens unit and the fourth lens unit at the telephoto end are β3t and β4t, respectively, and the maximum movement amount of the third lens unit during image stabilization is Dm. 7. A variable power optical system having an image stabilizing function according to claim 1, wherein the following conditions are satisfied.