JP2001066500A - Variable magnification optical system having vibration- proof function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a variable magnification optical system by which a still picture is obtained by optically correcting the blurring of a photographic picture when the variable magnification optical system is vibrated and which possesses a vibration-proof function. SOLUTION: This is the variable magnification optical system orderly having a first lens group L1 of positive refracting power, the second lens group L2 of negative refracting power, the third lens group L3 of positive refracting power and then the fourth lens group L4 of positive refracting power from an object side. In this case, variable magnification is executed by moving the first, second and fourth lens groups L1, L2 and L4 in an optical axis direction, and focusing is executed by moving the fourth lens group L4 in the optical axis direction, and the blurring of the photographic picture when the variable magnification optical system is vibrated is corrected by moving the whole third lens group L3 in the direction perpendicular to an optical axis, and the first lens group L1 possesses a meniscus negative lens having a concave surface on an image surface side on the most object side, and the second lens group L2 possesses the meniscus negative lens having the concave surface on the image surface side on the most object side, so that the moving quantities m1 and m2 of the first lens group L1 and the second lens group L2 required for the variable magnification from a wide angle end to the telephoto end are respectively appropriately set.

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. Video cameras, silver halide photography cameras, electronic still cameras, and the like, which stabilize the captured image by optically correcting the blur of the captured image when the camera vibrates (tilt) to obtain a still image
The present invention relates to a variable power optical system having a vibration reduction function suitable for a digital camera or the like.

[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, vibrations are transmitted to a photographing system, resulting in camera shake and blurring of the photographed image.

Conventionally, various anti-vibration optical systems having a function of preventing blurring of a captured image have been proposed.

For example, in Japanese Patent Application Laid-Open No. 56-21133, some optical members are moved in a direction to cancel the vibrational displacement of the image due to the vibration in response to the output signal from the detecting means for detecting the vibration state in the optical device. By doing so, the image is stabilized.

Japanese Patent Laid-Open Publication No. Sho 61-223819 discloses a photographing system in which a variable apex angle prism is arranged closest to the object side.
The image is stabilized by changing the apex angle of the variable apex angle prism according to the vibration of the photographing system.

Japanese Patent Application Laid-Open No. 1-116619 and Japanese Patent Application Laid-Open
In Japanese Patent Application Laid-Open No. 124452/1994, a still image is detected by detecting vibration of a photographing system using an acceleration sensor or the like, and vibrating some lens groups of the photographing system in a direction perpendicular to an optical axis according to a signal obtained at this time. Have gained.

In Japanese Patent Application Laid-Open No. Hei 7-128619, a third lens unit of a four-unit variable magnification optical system including four lens units having positive, negative, positive, and positive refractive powers has a positive and negative refractive power. Vibration is prevented by vibrating the positive lens group with two lens groups.

In Japanese Patent Application Laid-Open No. 7-199124,
Vibration reduction is performed by vibrating the entire third lens group of the four-unit variable power optical system including four lens groups having negative, positive, and positive refractive powers.

On the other hand, in Japanese Patent Application Laid-Open No. Hei 5-60974, a third lens group having four lens units having positive, negative, positive and positive refractive powers is composed of a positive lens and a meniscus-shaped negative lens. As a type, the overall length of the lens is shortened.

[0010]

Generally, an image stabilizing optical system is disposed in front of a photographing system, and a part of the movable lens group of the image stabilizing optical system is vibrated to eliminate blurring of a photographed image and obtain a still image. The method has a problem that the entire apparatus becomes large and a moving mechanism for moving the movable lens group becomes complicated.

Also, in an optical system that performs image stabilization using a variable apex angle prism, there is a problem that the amount of eccentric magnification chromatic aberration increases during image stabilization, especially on the long focal length side.

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

Further, the entire third lens group of the four-unit variable power optical system comprising four lens groups having positive, negative, positive and positive refractive powers is moved in a direction perpendicular to the optical axis to perform image stabilization. If the third
When the lens group is made up of a telephoto type of a positive lens and a meniscus negative lens in order to shorten the entire length, there is a problem that eccentric aberrations such as eccentric coma and eccentric field curvature occur to deteriorate image quality.

Further, the above-mentioned prior art having a zoom ratio of 8 times or more can be used for a video camera or the like, but is insufficient in aberration correction for use in an electronic still camera corresponding to one million pixels. .

According to the present invention, a relatively small and light lens group which forms 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). By configuring to correct the blur and by appropriately configuring the lens group for correcting the blur, it is possible to reduce the size of the entire apparatus, simplify the mechanism, and reduce the load on the driving unit. It is an object of the present invention to provide a variable power optical system having an image stabilizing function that satisfactorily corrects eccentric aberration when the lens group is decentered, and particularly has an image stabilizing function that can be applied to an electronic still camera having 1 million pixels or more. And

[0016]

According to the first aspect of the present invention, a variable power optical system having an image stabilizing function comprises a first lens unit having a positive refractive power and a second lens unit having a negative refractive power in order from the object side. A variable power optical system having a third lens group having a positive refractive power and a fourth lens group having a positive refractive power, wherein the first, second, and fourth lens groups are moved in the optical axis direction. The magnification is changed by the
The lens group is moved in the direction of the optical axis to perform focusing, and the entire third lens group is moved in the direction perpendicular to the optical axis to correct the blur of the captured image when the variable power optical system vibrates. The first lens group has a meniscus negative lens having a concave surface on the image surface side closest to the object side, the second lens group has a meniscus negative lens having a concave surface on the image surface side closest to the object side, When the moving amounts of the first lens unit and the second lens unit required for zooming from the wide-angle end to the telephoto end are respectively m1 and m2, 0.5 <| m1 / m2 | <2.5 (1) It is characterized by satisfying the following conditional expression.

The variable power optical system having an image stabilizing function according to the second aspect of the present invention includes, in order from the object side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a positive lens having a positive refractive power. Third lens group,
And a variable power optical system having a fourth lens group having a positive refractive power, wherein the first, second, and fourth lens groups are moved in the optical axis direction to perform zooming, and The group is moved in the direction of the optical axis to perform focusing, and the entire third lens group 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. Aperture is provided between the second lens group and the third lens group to adjust the focal length. The aperture stop moves on the optical axis with zooming, and its position is closer to the object side than the telephoto end at the wide angle end. When the moving amounts of the first lens unit and the second lens unit required for zooming from the wide-angle end to the telephoto end are respectively m1 and m2, 0.5 <| m1 / m2 | <2.5} ( 1) It is characterized by satisfying the following conditional expression.

[0018]

FIG. 1 is a schematic view showing a paraxial refractive power arrangement of Numerical Examples 1 to 3 of the present invention to be described later.

FIG. 2, FIG. 3, FIG. 4, and FIG. 5 are a sectional view of a lens and a diagram of aberrations at a wide-angle end, a middle position, and a telephoto end in a numerical example 1 of the present invention.

FIGS. 6, 7, 8, and 9 are a sectional view of a lens according to a second numerical embodiment of the present invention and aberration diagrams at the wide-angle end, at the middle, and at the telephoto end.

FIG. 10, FIG. 11, FIG. 12, and FIG. 13 are a sectional view of a lens according to a numerical example 3 of the present invention and aberration diagrams at a wide-angle end, a middle position, and a telephoto end.

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

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 the present 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. FP denotes a flare cut stop, which is arranged on the image plane side of the third lens unit, and cuts off a flare component when image stabilization is performed by the third lens unit.

In this embodiment, when zooming from the wide-angle end to the telephoto end, the first lens unit is moved toward the object side and the second lens unit is moved toward the image plane side as indicated by the arrow, and the image plane fluctuation due to zooming is changed to the fourth. The correction is made by moving the group.

Also, a rear focus system 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 third lens unit is fixed during zooming and focusing, but may be moved as needed.

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.

In this embodiment, as compared with the conventional so-called four-unit zoom lens, in which the first unit is extended to perform focusing, the above-described rear focus method is employed to prevent performance deterioration due to the eccentric error of the first unit. First while doing
This effectively prevents the effective lens diameter of the group from increasing.

The aberration fluctuation caused by the movable lens group is reduced by moving the aperture stop immediately before the third lens group at the telephoto end and closer to the object side at the telephoto end than at the wide-angle end as indicated by the arrow with the magnification change. The diameter of the front lens can be easily reduced by shortening the distance between the lens groups in front of the aperture stop.

Further, with respect to the amount of movement of the first lens unit and the second lens unit, the first required for zooming from the wide-angle end to the telephoto end.
When the movement amounts of the lens unit and the second lens unit are m1 and m2, respectively, the following conditional expression is satisfied: 0.5 <| m1 / m2 | <2.5 (1), and the total lens length at the wide-angle end is reduced. Has been achieved.

If the amount of movement of the first lens unit is smaller than the lower limit of conditional expression (1), the effect of shortening the total length at the wide angle end becomes insufficient. The locus of movement of the four lens groups at the telephoto end becomes too steep, so that the motor or the like cannot follow.

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, referring to FIG. 14, the optical principle of the image stabilizing system for correcting the blur 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.

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 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 instantaneously tilts due to camera shake as in FIG. 4 (B), 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 shift amount (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 Is the TS, the movement amount Δ is given by the following equation: Δ = f · tan (θ) / TS.

If the sensitivity TS of the eccentricity 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 the 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 required 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 residual 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 invention, the first lens group is a meniscus eleventh lens in which a concave surface having a stronger refractive power is directed toward the image surface side than the object side in order from the object side, a twelfth lens whose both lens surfaces are convex, Meniscus positive thirteenth with the convex surface facing the side
It consists of a lens.

In a variable power optical system having a certain wide angle of view as in the present invention, the object side of the first lens unit is preferably a negative lens by reducing the distance between the principal points of the first and second units. This is advantageous in reducing the ball diameter.

From the viewpoint of correcting distortion at the wide-angle end, it is preferable that the negative lens closest to the object has a negative meniscus lens shape with a strong concave surface facing the image plane.

The second lens group includes, in order from the object side, a negative twenty-first meniscus lens having a concave surface that is stronger on the image surface side than the object side, a negative second lens having both lens surfaces concave,
The lens has a positive meniscus 23rd lens with the convex surface facing the object side.

The configuration having a negative lens on the object side of the second lens group is more advantageous in correcting coma and field curvature occurring at the wide-angle end.

Further, a negative lens is further provided on the image plane side of the second lens group to form a lens configuration including four lens groups of negative, negative, positive, and negative, thereby reducing the front-back symmetry of the second lens group. This enhances the achromatizing effect of the principal point and effectively corrects chromatic aberration of magnification.

In this embodiment, the third lens unit is composed of a positive first lens L31 having a convex lens surface on the object side in order from the object side, and a negative meniscus second lens L32 having a stronger concave surface facing the image surface side than the object side. The lens L32 is composed of a positive thirty-third lens L33 whose both lens surfaces are convex. Positive 31st lens L31
Has an aspherical surface on the object side.

By providing a meniscus negative second 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. In addition, the overall length of the lens has been reduced.

When such a meniscus-shaped negative lens is provided, positive distortion occurs on the lens surface. This causes the eccentric distortion during vibration isolation to increase.

In order to reduce this decrease, it is sufficient to reduce the distortion generated in the entire third lens unit.

In this embodiment, the negative 32nd meniscus
By disposing a positive third lens L33 on the image plane side of the lens L32, while maintaining a certain degree of telephoto configuration, distortion is corrected in the third lens group, and the third lens group is shifted to perform image stabilization. The occurrence of eccentric distortion occurring when performing the method is reduced.

In the present embodiment, by providing an aspherical surface on the 31st lens, spherical aberration is suppressed by the third lens group, and eccentric coma generated during image stabilization is reduced.

In the present invention, since the fourth lens unit is composed of two positive lenses and one negative lens, spherical aberration and field curvature caused by the movement of the fourth lens unit during zooming or focusing. Has been reduced.

The present invention employs the above-described configuration to reduce various chromatic aberrations such as chromatic aberration of magnification caused by zooming in an optical system such as a digital still camera lens which requires a high resolution. It is better corrected than.

The variable power optical system having the image stabilizing function of the present invention can be realized by satisfying the above conditions. However, in order to achieve a good optical performance while further shortening the overall length of the lens. Preferably satisfies at least one of the following conditions.

(A-1) The second lens group includes, in order from the object side, a negative meniscus lens having a concave surface facing the image surface side, a negative lens, and a positive lens having a convex surface facing the object side.

(A-2) The first lens group includes, in order from the object side, a negative meniscus lens having a concave surface facing the image surface side, a positive lens, and a positive lens having a convex surface facing the object side.

(A-3) When the focal lengths of the entire system at the wide-angle end and the telephoto end are fw and ft, respectively, and the focal length of the second lens unit is f2.

[0064]

(Equation 3)

The following conditional expression must be satisfied.

Conditional expression (2) is intended to shorten the overall length of the lens while maintaining high optical performance in the present invention.

When the refractive power of the second lens unit is increased beyond the lower limit value of the conditional expression (2), the amount of movement of the second lens unit during zooming is reduced, but the Petzval sum increases in the negative direction as a whole. This is not preferable because it becomes difficult to correct field curvature.

Conversely, if the value exceeds the upper limit of (2), the amount of movement of the second lens unit at the time of zooming becomes large, so that the entire lens system is not reduced in size and disadvantageous with respect to a change in peripheral light quantity during image stabilization. Not so good.

(A-4) When the focal lengths of the entire system at the wide-angle end and the telephoto end are respectively fw and ft, and the focal length of the first lens unit is f1.

[0070]

(Equation 4)

That is,

If the refracting power of the first lens unit becomes too strong beyond the lower limit value of the conditional expression (3), it is advantageous for shortening the total length, but disadvantageously causes image plane collapse due to manufacturing errors and image fluctuation at zooming. Therefore, high lens barrel accuracy is required.

Conversely, if the value exceeds the upper limit, the amount of movement of the first lens unit becomes too large, which is not good.

(A-5) To effectively correct chromatic aberration of magnification, the negative twenty-fourth lens L closest to the image plane in the second lens group is used.
24 is f24, and the focal length of the second lens group is f
When it is set to 2, it is preferable to satisfy the following conditional expression: 1.4 <| f24 / f2 | <4.6 (4)

When the value exceeds the upper limit of conditional expression (4) and the negative
If the focal length of the lens L24 is too small, the effect of correcting chromatic aberration will be insufficient. Conversely, if the value exceeds the lower limit, it becomes difficult to correct distortion at the wide-angle end.

(A-6) In order to reduce the size of the entire optical system by using the third lens group as a telephoto type in the present invention, the third lens group and the negative 32nd lens L32 in the third lens group must be used. When the focal lengths are f3 and f32, respectively, it is desirable to satisfy the following conditional expression: 1.1 <| f32 / f3 | <3.5 (5)

If the refractive power of the negative 32nd lens in the third lens unit is increased beyond the lower limit of conditional expression (5), it is advantageous for shortening the overall length of the lens, but the Petzval sum increases in the negative direction. It is not good because the correction of the curvature of field becomes difficult.

Conversely, if the lower limit value is exceeded, the reduction of the overall length becomes insufficient, the chromatic aberration in the third lens group is not sufficiently corrected, and the chromatic aberration of eccentric magnification increases, which is not good.

(A-7) The variable power optical system has an aperture stop, and the maximum aperture diameter of the aperture stop can be varied according to the focal length at the time of variable power.

In order to reduce the change in light quantity during image stabilization, it is preferable to relatively increase the peripheral light quantity by reducing the aperture diameter on the telephoto side during zooming to restrict the central light beam.

(A-8) Appropriately setting the sensitivity of the shift group for image stabilization greatly affects the image stabilization performance.

Assuming that the focal length of the entire system at the wide-angle end is fw, it is preferable to satisfy the following condition: 2.5 <f3 / fw <4.0 (6) Thus, the sensitivity of the shift lens group is set to an appropriate value while shortening the overall length of the lens.

If the refractive power of the third lens group is increased beyond the lower limit value of the conditional expression (6), the sensitivity of the shift lens group becomes too large. It is not good because it becomes.

Conversely, if the refractive power of the third lens group is weakened beyond the upper limit, the amount of shift of the third lens group necessary for image stabilization becomes large, or the overall length of the lens becomes large. Not good.

(A-9) It is preferable to introduce an aspherical surface into the fourth lens group in order to correct fluctuations in astigmatism and distortion during zooming.

(A-10) In the present invention, since the third lens group moves for image stabilization, it is necessary to increase the lens diameter accordingly. Therefore, it is desirable to dispose a fixed stop on the object side or the image plane side of the third lens unit in order to prevent excessive on-axis light flux from entering.

In this embodiment, a fixed stop is arranged between the third lens unit and the fourth lens unit so as to effectively use a space and prevent unnecessary light beams from entering.

(A-11) The first lens group includes a negative meniscus eleventh lens having a convex surface facing the object side, a positive twelfth lens having both lens surfaces convex, and a convex surface facing the object side. It consists of a meniscus positive thirteenth lens.

(A-12) The second lens group is a negative twenty-first meniscus lens having a strong concave surface facing the image side in order from the object side, a negative second lens having both concave lens surfaces, and both lenses. The lens surface is composed of a positive twenty-third lens having a convex surface, and both lens surfaces are composed of a negative twenty-fourth lens having a concave surface.

Next, numerical examples of the present invention will be described. In the numerical examples, Ri is the radius of curvature of the ith lens surface in order from the object side, Di is the ith lens thickness and air spacing in order from the object side, and Ni and νi are the ith lens in order from the object side. Are the refractive index and Abbe number of the glass.

Table 1 shows the relationship between the above-mentioned 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, R represents a paraxial radius of curvature, and A, B, C, D, and E represent aspherical coefficients. When

[0092]

(Equation 5)

This is represented by the following equation. “E-0X” means “× 10 ^−X ”. (Numerical Example 1) f = 1 to 7.80 Fno = 2.85 to 3.29 2 = 58.2 ° to 8.2 ° R 1 = 7.007 D 1 = 0.23 N 1 = 1.846660 1 = 23.8 R 2 = 4.237 D 2 = 1.05 N 2 = 1.487490 2 = 70.2 R 3 = -43.624 D 3 = 0.03 R 4 = 3.696 D 4 = 0.60 N 3 = 1.696797 3 = 55.5 R 5 = 9.703 D 5 = Variable R 6 = 6.815 D 6 = 0.13 N 4 = 1.804000 4 = 46.6 R 7 = 0.842 D 7 = 0.33 R 8 = -4.304 D 8 = 0.11 N 5 = 1.805181 5 = 25.4 R 9 = 2.509 D 9 = 0.09 R10 = 1.703 D10 = 0.36 N 6 = 1.846660 6 = 23.8 R11 = -3.222 D11 = 0.10 N 7 = 1.772499 7 = 49.6 R12 = 10.961 D12 = Variable R13 = Aperture stop D13 = 0.75 R14 = 3.079 D14 = 0.33 N 8 = 1.583126 8 = 59.4 R15 = 8.333 D15 = 0.17 R16 = 26.006 D16 = 0.12 N 9 = 1.761821 9 = 26.5 R17 = 3.385 D17 = 0.04 R18 = 2.852 D18 = 0.42 N10 = 1.487490 10 = 70.2 R19 = -1.754 D19 = 0.28 R20 = Fixed mask D20 = Variable R21 = 5.541 D21 = 0.33 N11 = 1.603112 11 = 60.6 R22 = -5.206 D22 = 0.03 R23 = 2.309 D23 = 0.45 N12 = 1.487490 12 = 70.2 R24 = -4.278 D24 = 0.10 N13 = 1.846660 13 = 23.8 R25 = 6.596 D25 = 0.42 R26 = ∞ D26 = 0.57 N14 = 1.516330 14 = 64.1 R27 = ∞ ＼focal length 1.00 3.85 7.80 variable interval＼ D 5 0.13 2.88 3.66 D12 1.62 0.56 0.27 D20 1.18 0.92 1.60 Aspheric coefficient R14 K = -1.95782e + 01 B = 3.07372e-02 C = -4.20050e-02 D = -1.41126e-01 E = 3.38109e-01 (Numerical Example 2) f = 1 to 7.82 Fno = 2.85 to 3.28 2 = 59.9 ° to 8.4 ° R 1 = 7.078 D 1 = 0.24 N 1 = 1.846660 1 = 23.8 R 2 = 4.219 D 2 = 1.09 N 2 = 1.487490 2 = 70.2 R 3 = -35.676 D 3 = 0.03 R 4 = 3.697 D 4 = 0.62 N 3 = 1.696797 3 = 55.5 R 5 = 10.401 D 5 = Variable R 6 = 8.090 D 6 = 0.13 N 4 = 1.804000 4 = 46.6 R 7 = 0.861 D 7 = 0.36 R 8 = -5.145 D 8 = 0.11 N 5 = 1.761821 5 = 26.5 R 9 = 2.344 D 9 = 0.09 R10 = 1.634 D10 = 0.37 N 6 = 1.846660 6 = 23.8 R11 = -3.154 D11 = 0.10 N 7 = 1.804000 7 = 46.6 R12 = 5.740 D12 = Variable R13 = Aperture stop D13 = 0.78 R14 = 3.306 D14 = 0.34 N 8 = 1.583126 8 = 59.4 R15 = 8.621 D15 = 0.17 R16 = 58.936 D16 = 0.12 N 9 = 1.761821 9 = 26.5 R17 = 3.490 D17 = 0.04 R18 = 2.889 D18 = 0.45 N10 = 1.487490 10 = 70.2 R19 = -1.748 D19 = 0.29 R20 = Fixed mask D20 = Variable R21 = 4.968 D21 = 0.34 N11 = 1.603112 11 = 60.6 R22 = -5.985 D22 = 0.03 R23 = 2.729 D23 = 0.47 N12 = 1.487490 12 = 70.2 R24 = -4.25 3 D24 = 0.10 N13 = 1.846660 13 = 23.8 R25 = 10.475 D25 = 0.52 R26 = ∞ D26 = 0.59 N14 = 1.516330 14 = 64.1 R27 = ∞ ＼ Focal length 1.00 3.88 7.82 Variable interval＼ D 5 0.14 2.75 3.48 D12 1.66 0.58 0.28 D19 0.29 0.29 0.29 D20 1.33 0.99 1.59 Aspheric coefficient R14 K = -2.15623e + 01 B = 2.74346e-02 C = -8.17342e-02 D = 7.65222e-02 E = -7.44109e-03 (Numerical example 3) f = 1 to 7.81 Fno = 2.85 to 2.91 2 = 59.0 ° to 8.3 ° R 1 = 6.527 D 1 = 0.24 N 1 = 1.846660 1 = 23.8 R 2 = 4.166 D 2 = 1.07 N 2 = 1.496999 2 = 81.5 R 3 = -64.853 D 3 = 0.03 R 4 = 3.788 D 4 = 0.63 N 3 = 1.696797 3 = 55.5 R 5 = 10.499 D 5 = Variable R 6 = 8.951 D 6 = 0.12 N 4 = 1.804000 4 = 46.6 R 7 = 0.883 D 7 = 0.37 R 8 = -3.564 D 8 = 0.11 N 5 = 1.761821 5 = 26.5 R 9 = 2.669 D 9 = 0.09 R10 = 1.834 D10 = 0.36 N 6 = 1.846660 6 = 23.8 R11 = -2.415 D11 = 0.10 N 7 = 1.772499 7 = 49.6 R12 = 8.048 D12 = Variable R13 = Aperture stop D13 = 0.25 R14 = 2.836 D14 = 0.31 N 8 = 1.583126 8 = 59.4 R15 = 8.475 D15 = 0.17 R16 = 59.197 D16 = 0.12 N 9 = 1.761821 9 = 26.5 R17 = 3.125 D17 = 0.04 R18 = 2.844 D18 = 0.39 N10 = 1.487490 10 = 70.2 R19 = -1.930 D19 = 0.29 R20 = Fixed mask D20 = Variable R21 = 7.100 D21 = 0.37 N11 = 1.603112 11 = 60.6 R22 = -4.356 D22 = 0.03 R23 = 2.292 D23 = 0.49 N12 = 1.487490 12 = 70.2 R24 = -4.041 D24 = 0.10 N13 = 1.846660 13 = 23.8 R25 = 12.432 D25 = 0.51 R26 = ∞ D26 = 0.58 N14 = 1.516330 14 = 64.1 R27 = ∞ ＼ Focal length 1.00 3.82 7.81 Variable interval＼ D5 0.14 2.71 3.43 D12 2.14 0.68 0.27 D20 1.56 1.26 1.82 Aspheric surface coefficient R14 K = -4.97271e + 00 B = -9.62198e-03 C = -2.42223e-02 D = 6.94986e-02 E = -8.29702e-02

[0094]

[Table 1]

[0095]

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. The apparatus is configured to correct the image blur caused by (tilting) and the lens group for correcting the image blur is appropriately configured, so that the entire apparatus can be downsized, the mechanism can be simplified, and the driving unit can be used. With a vibration reduction function that satisfactorily corrects the eccentric aberration when the lens group is decentered while reducing the load on the camera, and in particular, has a vibration reduction function that can also be used for electronic still cameras with 1,000,000 pixels or more. Variable power optics 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 diagram showing various aberrations at the wide-angle end according to Numerical Embodiment 1 of the present invention.

FIG. 4 is a diagram showing various aberrations in the middle of Numerical Embodiment 1 of the present invention.

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

FIG. 6 is a sectional view of a lens at a wide-angle end according to a second numerical embodiment of the present invention.

FIG. 7 is a diagram showing various aberrations at the wide-angle end according to Numerical Example 2 of the present invention;

FIG. 8 is a diagram showing various aberrations in the middle of 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 sectional view of a lens at a wide-angle end according to a third numerical embodiment 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 showing various aberrations in the middle of the 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 SP stop IP image plane FP flare stop (fixed stop) d d-line g g-line ΔM meridional image plane ΔS sagittal image plane

Continued on the front page F term (reference) 2H087 KA02 KA03 MA15 NA07 PA10 PA20 PB13 QA02 QA06 QA17 QA21 QA25 QA39 QA41 QA45 RA05 RA12 RA31 RA36 RA42 SA23 SA27 SA29 SA32 SA62 SA63 SA65 SA74 SB04 SB15 SB24 SB34

Claims (9)

[Claims] 1. A first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power are arranged in order from the object side. A variable power optical system, wherein the first, second, and fourth lens groups are moved in the optical axis direction to perform zooming, and the fourth lens group is moved in the optical axis direction to focus. The entire third lens group is moved in the direction perpendicular to the optical axis to correct the blur of the photographed image when the variable power optical system vibrates, and the first lens group is closest to the object side and closer to the image plane. The second lens group has a meniscus-shaped negative lens having a concave surface on the image surface side closest to the object side, and the second lens group has a meniscus-shaped negative lens that has a concave surface on the image plane side, and is required for zooming from the wide angle end to the telephoto end. When the movement amounts of the first lens unit and the second lens unit are respectively m1 and m2, the following conditional expression is satisfied: 0.5 <| m1 / m2 | <2.5 Variable magnification optical system having a vibration reduction function and satisfying. 2. A first lens group having a positive refractive power, a second lens group having a negative refractive power, a third lens group having a positive refractive power, and a fourth lens group having a positive refractive power are arranged in order from the object side. A variable power optical system, wherein the first, second, and fourth lens groups are moved in the optical axis direction to perform zooming, and the fourth lens group is moved in the optical axis direction to focus. And moving the entire third lens group in the direction perpendicular to the optical axis to correct the blur of the captured image when the variable power optical system vibrates, and to provide an aperture stop for adjusting the amount of light passing through the second lens group. Provided between the group and the third lens group,
The aperture stop moves on the optical axis with zooming, and is located on the object side from the telephoto end at the wide-angle end, and the first lens group and the second lens group required for zooming from the wide-angle end to the telephoto end. A variable power optical system having an anti-vibration function, satisfying the following conditional expression: 0.5 <| m1 / m2 | <2.5, where m1 and m2 are the moving distances of m1 and m2, respectively. 3. A meniscus negative lens having a concave surface facing the image surface side in order from the object side, a negative lens,
3. The variable power optical system according to claim 1, further comprising a positive lens having a convex surface facing the object side. 4. A meniscus negative lens, a positive lens having a concave surface facing the image surface side in order from the object side,
4. The variable power optical system according to claim 1, further comprising a positive lens having a convex surface facing the object side. 5. When the focal lengths of the entire system at the wide-angle end and the telephoto end are respectively fw and ft, and the focal length of the second lens group is f2. 5. A conditional expression that satisfies the following conditional expression:
A variable power optical system having a vibration reduction function according to any one of the above. 6. When the focal lengths of the entire system at the wide-angle end and the telephoto end are fw and ft, respectively, and the focal length of the first lens unit is f1. 6. A conditional expression which satisfies the following conditional expression:
A variable power optical system having the vibration reduction function according to any one of the above. 7. The variable power optical system according to claim 1, wherein the variable power optical system has an aperture stop, and the maximum aperture diameter of the aperture stop is variable according to a focal length at the time of variable power. Variable magnification optical system with anti-vibration function. 8. The first lens group includes a negative meniscus eleventh lens having a convex surface facing the object side, a positive twelfth lens having both lens surfaces convex, and a meniscus-shaped negative meniscus lens having a convex surface facing the object side. 3. The variable power optical system according to claim 1, comprising a positive thirteenth lens. 9. The second lens group includes, in order from the object side, a negative twenty-first meniscus lens having a strong concave surface facing the image surface side, a negative second lens having both lens surfaces concave, and both lens surfaces being convex. 3. A variable power optical system having an anti-vibration function according to claim 1, wherein said positive 23rd lens comprises a negative 24th lens having both concave surfaces.