JP2002365551A - Zoom lens and optical equipment having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a zoom lens, capable of properly correcting image blurs caused when the zoom lens is vibrated, and to provide optical equipment using the zoom lens. SOLUTION: The zoom lens is provided with a 1st group L1 having positive refractive power, a 2nd lens group L2 having positive refractive power and a 3rd lens group L3 having negative refractive power, in this order starting from the object side, and realizes variable power by moving each lens group so that the space between the 1st and 2nd lens groups L1 and L2 becomes larger and the space between the 2nd and the 3rd lens groups L2 and L3 becomes smaller at a telephoto end than at a wide-angle end. An image-forming position is displaced, by moving a lens group B12 having negative refractive power which is one part in the 1st lens group L1, so as to have components in a perpendicular direction to the optical axis.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a zoom lens and an optical apparatus having the same. For example, the present invention relates to a zoom lens and an optical device having the same. A film camera, video camera, electronic camera,
It is suitable for digital cameras and the like.

[0002]

2. Description of the Related Art In recent years, optical equipment such as a photographic lens and a video lens has an image blur correcting means for correcting an image blur caused by a camera shake for the purpose of higher image quality and expansion of shooting conditions. Various zoom lenses have been proposed.

For example, in Japanese Patent Application Laid-Open No. 9-230236, a third lens group is made positive by a four-group zoom lens including first, second, third, and fourth lens groups having positive, negative, positive, and positive refractive powers. ,
Image blur correction is performed by separating the lens unit into a lens unit having a positive refractive power and moving the rear lens unit in a direction perpendicular to the optical axis.

In Japanese Patent Application Laid-Open No. Hei 10-232420, a four-unit zoom mainly including a first, second, third, and fourth lens units having positive, negative, positive, and positive refractive power is mainly used as a video zoom lens. During zooming, the first and third lens groups are fixed, the third lens group is separated into lens groups having positive and negative refractive power, and one of the lens groups is moved in a direction perpendicular to the optical axis. Thus, image blur correction is performed.

In Japanese Patent Application Laid-Open No. H11-52243, the first lens unit is moved in a direction perpendicular to the optical axis by a three-unit zoom including first, second, and third lens units having positive, positive, and negative refractive powers. Image blur correction is performed by moving.

In Japanese Patent Application Laid-Open No. 6-265827,
In order from the object side, the zoom lens system includes three lens units, a first lens unit having a positive refractive power, a second lens unit having a positive refractive power, and a third lens unit having a negative refractive power, and performs zooming from a wide-angle end to a telephoto end. In this case, the distance between the first lens group and the second lens group is increased, and the distance between the second lens group and the third lens group is reduced. The second lens group is divided into a front group and a rear group, and the rear group. Discloses a zoom lens in which image blur has been corrected by moving in the direction perpendicular to the optical axis.

In Japanese Patent Application Laid-Open No. 8-82770, a first lens group having a positive refractive power, a second lens group having a positive refractive power, a stop, and a third lens group having a negative refractive power are arranged in this order from the object side. The second lens group is configured such that the distance between the first lens group and the second lens group increases and the distance between the second lens group and the third lens group decreases during zooming from the wide-angle end to the telephoto end. Discloses a zoom lens in which image blur has been corrected by moving in the direction perpendicular to the optical axis.

[0008]

Generally, in an optical system for correcting image blur by decentering a part of the lens of the photographing system in a direction perpendicular to the optical axis, an extra extra lens is required for image blur correction. Although there is an advantage that an optical system is not required, there is a problem that a space for a lens group to be moved is required, and eccentric aberration is generated at the time of image blur correction.

If the number of lens components of the correction lens group for performing image blur correction is large, the weight becomes heavy, and a large torque is required when performing electric driving, and it is difficult to correct image blur quickly and accurately. Come.

In Japanese Patent Application Laid-Open No. H11-52243, image blur correction is performed by decentering the entire first lens unit. Therefore, the correction optical system becomes heavy and an appropriate amount of image blur correction with respect to the amount of eccentricity is provided. And it was difficult to obtain good optical performance at the time of eccentricity.

In addition, in order to correct image blur, it is necessary to appropriately set the amount of movement (the amount of eccentricity) of the correction optical system for obtaining a certain amount of image blur correction effect.

For example, if the effect of correcting the image blur for a certain movement of the correction optical system is enhanced, the effect of the imaging displacement becomes too sensitive to the eccentricity, so that the correction of the certain image blur can be accurately performed. It becomes difficult to control the movement of the correction optical system.

The present invention reduces the size of the correction optical system while maintaining high image quality and performs a certain amount of image blur correction effect by appropriately setting the configuration and the like of the zoom lens and the correction lens group. The objective is to provide a zoom lens capable of easily controlling the amount of movement of the correction optical system for the purpose of performing the above-mentioned operation, and performing good electrical driving of the correction optical system, and an optical apparatus having the same.

[0014]

According to a first aspect of the present invention, there is provided a zoom lens having a first lens unit having a positive refractive power, a second lens unit having a positive refractive power, and a second lens unit having a negative refractive power. Each lens group has three lens groups. The distance between the first lens group and the second lens group at the telephoto end with respect to the wide-angle end is large, and the distance between the second lens group and the third lens group is small. Displacement of the image forming position by moving and changing the magnification and moving a part of the first lens unit having a negative refractive power in a direction perpendicular to the optical axis. It is characterized by.

According to a second aspect of the present invention, in the first aspect, the first lens group includes, in order from the object side, a B11 lens group having a positive refractive power, a B12 lens group having a negative refractive power, and a positive refractive power. B13 lens group, and the imaging position is displaced by moving the B12 lens group so as to have a component perpendicular to the optical axis.

In a third aspect of the present invention, the radius of curvature of the lens surface closest to the image plane in the B12 lens group is RB12b, and the radius of curvature of the lens surface closest to the object side in the B13 lens group is RB13a. −0.2 <(RB12b−RB13a) / (RB12b +
RB13a) <0.15.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the focal length of the entire system at the wide-angle end zoom position is Fw, the focal length of the first lens is F1, and the B12 When the focal length of the lens group is FB12, the lens satisfies the following conditional expression: 1.5 <F1 / Fw <50.5 <| F1 / FB12 | <3.5.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, when the focal length of the entire system at the wide-angle end is Fw and the focal length of the i-th lens unit is Fi, 0.4 <F2 / Fw <1.20.3 <| F3 / Fw | <1.2 The following conditional expression is satisfied.

According to a sixth aspect of the present invention, in the first aspect of the present invention, the B11 lens group is composed of a meniscus positive lens having a convex surface facing the object side, and a negative lens having both concave surfaces concave. It is characterized by becoming.

According to a seventh aspect of the present invention, in any one of the first to fifth aspects of the present invention, the B11 lens unit includes a cemented lens of a positive lens and a negative lens having both convex surfaces. .

According to an eighth aspect of the present invention, in the first aspect of the invention, the B12 lens group comprises a cemented lens of a negative lens and a positive meniscus lens having a convex surface facing the object side. It is characterized by.

According to a ninth aspect of the present invention, in any one of the first to eighth aspects of the present invention, the B13 lens unit comprises a positive lens having both lens surfaces convex.

According to a tenth aspect of the present invention, in the first aspect of the present invention, the second lens group is a negative meniscus lens having a convex surface facing the image surface side, the second lens group being located on the image side as compared with the object side. It is characterized in that both lens surfaces having a strong refractive power are composed of convex positive lenses.

According to an eleventh aspect of the present invention, in any one of the first to tenth aspects, the third lens group includes a negative lens having a concave surface facing the object side.

According to a twelfth aspect of the present invention, in any one of the first to eleventh aspects, the displacement of the image forming position is intended to correct image blur.

According to a thirteenth aspect of the present invention, there is provided an optical apparatus including the zoom lens according to any one of the first to twelfth aspects.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a zoom lens according to the present invention and an optical apparatus having the same will be described with reference to the drawings.

FIGS. 1, 11, and 21 are sectional views of the zoom lenses of Numerical Embodiments 1 to 3 at the wide-angle end, and FIGS. 2 to 10 are aberrations of the zoom lens of Numerical Embodiment 1 of the present invention. FIGS. 12 to 20 are aberration diagrams of the zoom lens according to Numerical Example 2 of the present invention, and FIGS. 22 to 30 are aberration diagrams of the zoom lens of Numerical Example 3 of the present invention.

In the lens sectional views of the zoom lenses of the numerical examples, L1 denotes a first group having a positive refractive power (first lens group), L2 denotes a second group having a positive refractive power (second lens group), L
Reference numeral 3 denotes a third group (third lens group) having negative refractive power. SP
Is an aperture, and IP is an image plane.

The first unit L1 includes a B11 lens unit LB11 having a positive refractive power, a B12 lens unit LB12 having a negative refractive power, and a B13 lens unit LB13 having a positive refractive power.

In the zoom lens according to the present embodiment, when the magnification is changed from the wide-angle end to the telephoto end, the first unit L1 and the second unit L1 are moved.
The first, second, and third groups are moved to the object side as indicated by arrows so that the distance between the groups L2 increases and the distance between the second group L2 and the third group L3 decreases.

At this time, the main zooming operation is performed by changing the air gap between the second lens unit L2 and the third lens unit L3, and the first lens unit L1 and the second lens unit L2 are further moved from the wide-angle end to the telephoto end. By further narrowing the air interval (interval), a further zooming action is performed, and at the same time, a change in the image plane during zooming is corrected.

Then, a lens unit having a negative refractive power in the first unit, for example, a B12 lens unit LB12 is used as a correction lens unit, and is moved (eccentric) so as to have a component perpendicular to the optical axis. Displaces the imaging position by
The shake of the captured image caused when the zoom lens vibrates is corrected.

Then, various aberrations caused by the eccentricity of the B12 lens unit LB12 are reduced by the other lens units LB11 and LB11 in the first unit.
At the same time as canceling by LB13, by setting the refractive power of the B12 lens unit LB12 optimally, the displacement of the imaging position with respect to a constant eccentricity is controlled and B
It is easy to obtain the optimal amount of movement for electrical drive of the twelfth lens group LB12.

FIGS. 8, 9 and 10 show lateral aberrations after the image position displacement corresponding to 0.5 ° of the angle of view at the wide angle end, the middle zoom position, and the telephoto end in Numerical Embodiment 1, respectively. At this time, the image position correcting lens group B12 moves 0.48 mm vertically downward with respect to the optical axis.

FIGS. 18, 19 and 20 show lateral aberrations after the image position displacement corresponding to 0.5 ° of the angle of view at the wide angle end, the middle zoom position, and the telephoto end in Numerical Embodiment 2, respectively. At this time, the image position correcting lens unit B12 moves 0.42 mm vertically downward with respect to the optical axis.

FIGS. 28, 29, and 30 show lateral aberrations after performing an image position displacement corresponding to 0.5 ° of the angle of view at the wide angle end, the intermediate zoom position, and the telephoto end in Numerical Embodiment 3, respectively. At this time, the image position correcting lens unit B12 moves 0.24 mm vertically downward with respect to the optical axis.

As described above, in the present embodiment, the first lens unit is divided into a B11 lens unit having a positive refractive power and a B11 lens having a negative refractive power from the object side.
By having 12 lens groups and a B13 lens group having a positive refractive power, and performing eccentric movement of the B12 lens group so as to have a component in a direction perpendicular to the optical axis, the aberration variation at the time of eccentricity can be reduced. The image position is being displaced.

More specifically, it is possible to control the angle of light rays incident on the B12 lens group by the convergence of the B11 lens group having a positive refractive power, and to easily control the amount of aberration change due to the eccentricity of the B12 lens group. At the same time, the size of the lens system of the B12 lens group is reduced, and at the same time, the size of the moving mechanism of the B12 lens group is easily reduced.

Further, the B13 lens group has a function of canceling the negative spherical aberration which is generated most on the image plane side of the B12 lens group, and further prevents the asymmetry of the spherical aberration generated when the B12 lens group is decentered. The generation of high-order coma is suppressed.

In this embodiment, focusing is performed in the second
The group has been moved.

The stop SP is close to the object side of the second lens unit, and moves together with the second lens unit or as indicated by a dotted arrow with zooming.

In the present embodiment, the above configuration prevents image deterioration due to image blur due to vibrations such as camera shake and prevents a change in image position from 3 to 3.5, which has an image position displacement effect capable of obtaining a high quality image. The zoom lens is about twice as large.

The objective zoom lens of the present invention can be achieved by satisfying the above-mentioned conditions, and more preferably at least one of the following conditions.

When the radius of curvature of the lens surface closest to the image plane in the B12 lens group is RB12b, and the radius of curvature of the lens surface closest to the object in the B13 lens group is RB13a, -0.2 <(RB12b- (RB13a) / (RB12b + RB13a) <0.15 (1)

Conditional expression (1) is mainly for obtaining a good image quality even when the imaging position is displaced by the B12 lens group. In particular, the asymmetry of the spherical aberration and the coma due to the parallel eccentric component of the B12 lens group are obtained. This is a condition for suppressing the occurrence of aberration.

Exceeding the numerical range of the conditional expression (1) is not preferable because the canceling relationship between spherical aberration and coma aberration on the mutual plane when the imaging position is displaced and when there is no displacement is broken.

More preferably, the numerical range of the conditional expression (1) is set to -0.15 <(RB12b-RB13a) / (RB12b + RB13a) <0.1 (1a).

The focal length of the entire system at the zoom position at the wide-angle end is Fw, the focal length of the first lens is F1, and the focal length of B12 is
Assuming that the focal length of the lens group is FB12, the following conditional expression is satisfied: 1.5 <F1 / Fw <5 (2) 0.5 <| F1 / FB12 | <3.5 (3) Is to satisfy.

The conditional expressions (2) and (3) are mainly used to reduce the diameter of the B12 lens group and reduce the weight of the B12 lens group while suppressing the image quality deterioration when the imaging position is displaced, and to drive the lens. This is to be advantageous.

If the refractive power of the first lens unit is weakened beyond the upper limit of conditional expression (2), the total length of the lens system increases in order to secure a constant focal length and a variable power ratio. Not good. On the other hand, if the lower limit is exceeded, the refracting power of the first lens group becomes too strong, and negative spherical aberration occurs strongly. It becomes difficult for the other lens groups to satisfactorily correct this during the entire zooming operation. Come.

Conditional expression (3) relates to the negative refractive power of the B12 lens unit for displacing the image forming position in the first lens unit. This is for maintaining high image quality while suppressing the moving amount.

When the value exceeds the upper limit of conditional expression (3), B12
The negative refracting power of the lens group becomes too large, and the positive refracting power of the lens system other than the B12 lens group in the first lens group must be increased, so that high-order spherical aberration and coma aberration largely occur. As a result, it becomes difficult to correct aberrations when the imaging position is displaced.

On the other hand, when the negative refractive power of the B12 lens group becomes weaker than the lower limit, the displacement of the B12 lens group increases in order to perform a displacement action of a fixed image position. In order to obtain a constant peripheral light amount, the lens diameter of the B12 lens group increases, which is not good.

The B12 lens group is preferably composed of one negative lens and one positive lens to form an achromatic lens as a whole, in order to suppress chromatic aberration fluctuations when the lens is moved when the imaging position is displaced.

More preferably, the numerical range of the conditional expressions (2) and (3) should be limited to the following.

2 <F1 / Fw <3 (2a) 1 <| F1 / FB12 | <2.6 (3a) The focal length of the entire system at the wide-angle end is Fw, the i-th lens Assuming that the focal length of the group is Fi, the following condition is satisfied: 0.4 <F2 / Fw <1.2 (4) 0.3 <| F3 / Fw | <1.2 (5) That is to satisfy the formula.

The conditional expressions (4) and (5) are mainly for achieving a high quality and compact optical system.

If the upper limit of conditional expression (4) is exceeded, the refractive power of the second lens unit will be weakened, and the amount of movement of each lens unit will be large in order to obtain a constant zoom ratio. It becomes difficult to make the system compact. If the lower limit value is exceeded, the effect of the positive refractive power becomes too large, and high-order spherical aberration is largely generated.

When the value exceeds the upper limit of conditional expression (5), the refracting power of the third lens unit becomes too weak, so that the back focus becomes long.

On the other hand, if the lower limit is exceeded, the back focus of the entire lens system becomes too short, and the outer diameter of the third lens group becomes large in order to obtain a constant amount of peripheral light. At the same time, the size of the optical device increases, and at the same time, large off-axis high-order aberrations such as field curvature occur.

Further, when the numerical ranges of the conditional expressions (4) and (5) are limited as follows, a more compact and high-quality optical system is achieved.

0.6 <F2 / Fw <1 (4a) 0.5 <| F3 / Fw | <0.9 (5a) The B11 lens group has a convex surface on the object side. A meniscus-shaped positive lens, and both lens surfaces are composed of concave negative lenses.

The B11 lens group is composed of a cemented lens composed of a positive lens and a negative lens both of which have convex surfaces.

The B12 lens group comprises a cemented lens of a negative lens and a meniscus-shaped positive lens with the convex surface facing the object side.

◎ The B13 lens group is composed of a positive lens whose both lens surfaces are convex.

The second lens group is composed of a negative meniscus lens having a convex surface facing the image surface side, and both positive lens surfaces having both convex surfaces having a stronger refractive power on the image surface side than the object side. . Furthermore, it is desirable to introduce an aspherical surface into the second lens group in order to achieve good image quality.

The third lens group has a negative lens whose concave surface faces the object side. Further, it is desirable to have at least one aspheric surface.

It is preferable to add an aspherical surface to the lens system and to introduce a diffractive optical element, a refractive index distribution type optical material, etc., in order to improve the optical performance.

Focusing from an object at infinity to a close object can be performed by moving the second lens unit to the object side. Focusing may be performed in combination with movement of another lens unit.

The first lens unit and the third lens unit may be moved together during zooming, which is advantageous for simplifying the lens driving mechanism.

It is desirable that the iris diaphragm be disposed between the first lens unit and the second lens unit.
It is preferable to make the movement independent of the other lens groups because the entrance pupil position can be optimally arranged.

Next, an embodiment of a lens shutter type compact camera using the zoom lens of the present invention as a photographing optical system will be described with reference to FIG.

In FIG. 31, reference numeral 10 denotes a compact camera main body, 11 denotes a photographing optical system constituted by the zoom lens of the present invention, 12 denotes a flash built in the camera main body,
13 is an external viewfinder, and 14 is a shutter button.

As described above, by applying the zoom lens of the present invention to an optical device such as a lens shutter camera,
Optical devices with small size and high optical performance are realized.

Next, numerical examples of the zoom lens according to the present invention will be described. In each numerical example, i indicates the order of the optical surfaces from the object side, Ri is the radius of curvature of the i-th optical surface (i-th surface), Di is the distance between the i-th surface and the (i + 1) -th surface, ni
And υi respectively indicate the refractive index and Abbe number of the material of the i-th optical member with respect to the d-line. K is the eccentricity, B,
When C, D, E,... Are aspherical coefficients, and the displacement in the optical axis direction at a height h from the optical axis is x with respect to the surface vertex, the aspherical shape is x = ( ^{h 2 / R) / [1+} [1- (1 + k) (h /
R) ² ] ^1/2 ] + Ah ² + Bh ⁴ + Ch ⁶ + Dh ⁸ + Eh
Displayed as ¹⁰ . Here, R is a radius of curvature. Table 1 shows the correspondence with the above-described conditional expressions in each numerical example.

[0077]

[Outside 1]

[0078]

[Outside 2]

[0079]

[Outside 3]

[0080]

[Table 1]

[0081]

According to the present invention, the correction optical system can be reduced in size while maintaining high image quality, and the amount of movement of the correction optical system for performing a certain amount of image blur correction effect can be easily controlled and corrected. It is possible to achieve a zoom lens that can favorably drive an optical system electrically and an optical apparatus having the same.

In addition, according to the present invention, the positive
In a zoom lens having lens units having positive and negative refractive powers, displacement of an image forming position is performed by moving some negative lens units in the first lens unit so as to have components in a direction perpendicular to the optical axis. In this case, it is possible to achieve a compact zoom lens having a high zoom ratio capable of maintaining good optical performance and an optical apparatus using the same.

[Brief description of the drawings]

FIG. 1 is a sectional view of a zoom lens according to a first numerical example of the present invention at a wide-angle end.

FIG. 2 is a longitudinal aberration diagram at a wide-angle end of a zoom lens according to Numerical Example 1 of the present invention.

FIG. 3 is a longitudinal aberration diagram at an intermediate zoom position of the zoom lens according to Numerical Embodiment 1 of the present invention.

FIG. 4 is a longitudinal aberration diagram at a telephoto end of a zoom lens according to Numerical Example 1 of the present invention.

FIG. 5 is a lateral aberration diagram of the zoom lens according to a numerical example 1 of the present invention before displacement of the image position at the wide-angle end.

FIG. 6 is a lateral aberration diagram before a displacement of an image position at an intermediate zoom position of the zoom lens according to Numerical Example 1 of the present invention;

FIG. 7 is a lateral aberration diagram of the zoom lens according to Numerical Example 1 of the present invention at the telephoto end before image position displacement.

FIG. 8 is a lateral aberration diagram of the zoom lens according to Numerical Embodiment 1 of the present invention after a displacement of an image position at an angle of view of 0.5 ° at the wide-angle end.

FIG. 9 is a lateral aberration diagram after a displacement of an image position at an angle of view of 0.5 ° at an intermediate zoom position of the zoom lens according to Numerical Example 1 of the present invention;

FIG. 10 is a lateral aberration diagram of the zoom lens according to Numerical Embodiment 1 of the present invention at the telephoto end after an image position displacement of 0.5 °.

FIG. 11 is a sectional view of a zoom lens according to a second numerical example of the present invention at the wide-angle end.

FIG. 12 is a longitudinal aberration diagram at a wide-angle end of a zoom lens according to Numerical Example 2 of the present invention.

FIG. 13 is a longitudinal aberration diagram at an intermediate zoom position of the zoom lens according to Numerical Example 2 of the present invention.

FIG. 14 is a longitudinal aberration diagram at a telephoto end of a zoom lens according to Numerical Example 2 of the present invention.

FIG. 15 is a lateral aberration diagram of the zoom lens according to Numerical Example 2 of the present invention before displacement of the image position at the wide-angle end.

FIG. 16 is a lateral aberration diagram of a zoom lens according to a second numerical example of the present invention at an intermediate zoom position before image position displacement.

FIG. 17 is a lateral aberration diagram of the zoom lens according to Numerical Example 2 of the present invention before displacement of the image position at the telephoto end.

FIG. 18 is a lateral aberration diagram of the zoom lens according to Numerical Example 2 of the present invention after a displacement of an image position at an angle of view of 0.5 ° at the wide-angle end.

FIG. 19 is a lateral aberration diagram of the zoom lens according to Numerical Example 2 of the present invention after an image position displacement of an intermediate zoom position at an angle of view of 0.5 °.

FIG. 20 is a lateral aberration diagram of the zoom lens according to Numerical Example 2 of the present invention after displacement of the image position at the telephoto end at an angle of view of 0.5 °.

FIG. 21 is a lens cross-sectional view at the wide-angle end of a zoom lens according to Numerical Example 3 of the present invention.

FIG. 22 is a longitudinal aberration diagram at the wide-angle end of a zoom lens according to Numerical Example 3 of the present invention.

FIG. 23 is a longitudinal aberration diagram at an intermediate zoom position of the zoom lens according to Numerical Example 3 of the present invention.

FIG. 24 is a longitudinal aberration diagram at the telephoto end of a zoom lens according to Numerical Example 3 of the present invention.

FIG. 25 is a lateral aberration diagram of the zoom lens according to Numerical Example 3 of the present invention before displacement of the image position at the wide-angle end.

FIG. 26 is a lateral aberration diagram before a displacement of an image position at an intermediate zoom position of the zoom lens according to Numerical Example 3 of the present invention;

FIG. 27 is a lateral aberration diagram of the zoom lens according to Numerical Example 3 of the present invention at the telephoto end before image position displacement.

FIG. 28 is a lateral aberration diagram of the zoom lens according to Numerical Example 3 of the present invention after displacement of the image position at the wide-angle end at an angle of view of 0.5 °.

FIG. 29 is a lateral aberration diagram after a displacement of an image position at an angle of view of 0.5 ° at an intermediate zoom position of the zoom lens according to Numerical Example 3 of the present invention;

30 is a lateral aberration diagram of the zoom lens according to Numerical Example 3 of the present invention at the telephoto end after a displacement of the image position at an angle of view of 0.5 °. FIG.

FIG. 31 is a sectional view of a main part of the optical apparatus of the present invention.

[Explanation of symbols]

 L1 First group LB11 B11 lens group LB12 B12 lens group LB13 B13 lens group L2 Second group L3 Third group SP Aperture IP Image plane d d-line g g-line ΔM Meridional image plane ΔS Sagittal image plane C sine condition

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H044 EF01 2H087 KA02 KA03 MA18 NA07 PA06 PA07 PA18 PA20 PB08 PB10 QA02 QA06 QA07 QA12 QA14 QA22 QA26 QA37 QA39 QA41 QA46 RA05 RA13 RA32 SA13 SA16 SA20 SB06 SB22 SA63 AA00 AB55 AB66 AC54

Claims (13)

[Claims] 1. A first lens unit having a positive refractive power, a second lens unit having a positive refractive power, and a third lens unit having a negative refractive power are arranged in order from the object side. The zooming is performed by moving each lens group so that the distance between the first lens group and the second lens group is large and the distance between the second lens group and the third lens group is small. A zoom lens characterized in that a part of the lens group having a negative refractive power is moved so as to have a component in a direction perpendicular to the optical axis, thereby displacing an image forming position. 2. The first lens group includes, in order from the object side, a B11 lens group having a positive refractive power, a B12 lens group having a negative refractive power, and a B13 lens group having a positive refractive power. 2. The zoom lens according to claim 1, wherein an image forming position is displaced by moving the group so as to have a component in a direction perpendicular to the optical axis. 3. When the radius of curvature of the lens surface closest to the image plane in the B12 lens group is RB12b, and the radius of curvature of the lens surface closest to the object in the B13 lens group is RB13a, -0.2 <(RB12b −RB13a) / (RB12b +
The zoom lens according to claim 2, wherein the following conditional expression is satisfied: RB13a) <0.15. 4. When the focal length of the entire system at the zoom position at the wide-angle end is Fw, the focal length of the first lens is F1, and the focal length of the B12 lens group is FB12, 1.5 <F1 / Fw. The zoom lens according to any one of claims 1 to 3, wherein the following conditional expression is satisfied: <50.5 <| F1 / FB12 | <3.5. 5. When the focal length of the entire system at the wide-angle end is Fw and the focal length of the i-th lens unit is Fi, 0.4 <F2 / Fw <1.20.3 <| F3 / Fw | < The zoom lens according to any one of claims 1 to 4, wherein the following conditional expression is satisfied. 6. The B11 lens unit according to claim 1, wherein said B11 lens group comprises a meniscus-shaped positive lens having a convex surface facing the object side, and a negative lens having both lens surfaces concave.
The zoom lens according to the item. 7. The zoom lens according to claim 1, wherein said B11 lens group comprises a cemented lens of a positive lens and a negative lens having both convex surfaces. 8. The lens system according to claim 1, wherein said B12 lens group comprises a cemented lens of a negative lens and a positive meniscus lens having a convex surface facing the object side.
The zoom lens according to the item. 9. The zoom lens according to claim 1, wherein said B13 lens group comprises a positive lens having both lens surfaces convex. 10. The second lens unit comprises a negative meniscus lens having a convex surface facing the image surface side, and both positive lens surfaces having a convex surface having a higher refractive power on the image surface side than the object side. The zoom lens according to any one of claims 1 to 9, wherein: 11. The apparatus according to claim 1, wherein said third lens group includes a negative lens having a concave surface facing the object side.
0. The zoom lens according to any one of 0. 12. The image forming apparatus according to claim 1, wherein the displacement of the image forming position is for correcting image blur.
The zoom lens according to any one of the above items. 13. An optical apparatus comprising the zoom lens according to claim 1. Description: