JP2020086133A - Zoom imaging optical system - Google Patents

Abstract

To provide a zoom optical system which features a fixed total length while zooming and focusing, suppressed manufacturing error sensitivity, a small image height change rate while wobbling, good optical performance over an entire range while zooming and focusing, anti-shake functionality, and minimized weight of an anti-shake lens group and focusing lens group.SOLUTION: A zoom imaging optical system comprises a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, an aperture stop, a fourth lens group having positive refractive power, a fifth lens group having negative refractive power, a sixth lens group having positive refractive power, and a seventh lens group having negative refractive power, in order from an object side to an image side, and is configured such that the first, fifth, and seventh lens groups are stationary relative to the image plane while zooming and that the sixth lens group moves toward the object side along an optical axis when shifting focus from an object at infinity to a nearby object.SELECTED DRAWING: Figure 1

Description

The present invention relates to a variable power imaging optical system having an image stabilizing function used in an image pickup apparatus such as a digital camera or a video camera.

Patent Documents 1 and 2 disclose a variable-magnification image-forming optical system that has a vibration-proof function and has a fixed total length when changing magnification, such as a photographic camera or a video camera.

JP, 2014-35480, A JP-A-2015-152665

In general, many optical systems (telephoto lenses) having a long focal length are large and heavy, and miniaturization of the entire length is desired. This is because the weight and diameter of the focusing lens group become large, which hinders high focusing speed and small diameter.

Also, in a variable-magnification imaging optical system with a narrow angle of view at the telephoto end, blurring of the captured image is likely to occur due to the effects of vibration such as camera shake, so some lens groups (anti-vibration lens groups) in the optical system It is required to have an anti-vibration function that corrects the blur of a captured image by displacing it in the direction perpendicular to the optical axis. Further, when the variable magnification imaging optical system has an image stabilizing function, it is required that the image stabilizing lens group has a small diameter and a small weight in order to avoid an increase in the size of the actuator for driving the image stabilizing lens group. To be done.

In addition, in the telephoto system, changing the weight balance during zooming causes a problem during shooting, so it is desired that the length be fixed as much as possible. In the conventional fixed-length variable-magnification imaging optical system, it is conceivable to increase the refractive power of each lens group in order to downsize the optical system. In particular, the second lens group, which mainly controls zooming, increases or decreases the amount of zooming movement due to its refracting power, which affects the downsizing of the entire length. However, if the refracting power is increased for downsizing, the sensitivity to manufacturing error is deteriorated.Therefore, high processing accuracy and assembly adjustment are required to ensure the optical performance of the actual product with the refracting power increased. Therefore, there remains a problem that the manufacturing cost rises.

In recent years, moving image shooting using a digital still camera has become common. In moving image shooting, the focus lens group is constantly vibrated (wobbling) in the optical axis direction in order to maintain the in-focus state with respect to the subject, thereby constantly detecting a change in contrast and determining the moving direction of the focus lens group. Many methods have been adopted. When the focus lens group is driven by the wobbling, if the weight of the focus lens group is large, the actuator for driving the focus lens group becomes large and it becomes difficult to reduce the size and weight of the taking lens. Further, if the focus lens group having a large weight is forcibly driven by the wobbling without increasing the size of the actuator, driving sound noise generated from the actuator is recorded as a sound in moving image shooting, which is a problem. Therefore, it is required to reduce the weight of the focus lens group in the variable-magnification imaging optical system adapted for shooting moving images.

Further, in such a focus method, if the rate of change in image height at the time of wobbling is large, there is a problem that the viewer recognizes the variation in magnification of the subject on the screen and feels uncomfortable. Therefore, a focus method is desired in which the rate of change in image height during wobbling is small.

The optical system disclosed in Patent Document 1 is a variable-magnification optical system that is composed of positive, negative, positive, and positive refracting powers in order from the object side, and has a fixed length during zooming and focusing. The fourth lens group is divided into three groups, positive, negative, and positive, and the center negative lens group is displaced in the orthogonal direction to the optical axis to realize a vibration isolation function. However, since the focus method has an inner focus structure in which the inside of the first lens group having the largest aperture is moved, it is difficult to achieve a high focusing speed and a small diameter. Further, there is a problem that the image height change rate at the time of focusing at the wide-angle end is large. Further, since the second lens group that mainly controls zooming has a high refractive power, there is a problem that the residual aberration of the second lens group is large and the manufacturing error sensitivity is high.

The optical system disclosed in Patent Document 2 is a variable-magnification optical system that is composed of positive, negative, positive, and positive refracting powers in order from the object side and has a fixed length during zooming and focusing. Further, the fourth lens group is divided into a first partial group having a positive refractive power, a second partial group having a negative refractive power, and a third partial group having a positive or negative refractive power, and the second partial group has a focus. It is a group and moves in the image direction when focusing on an object at infinity to a near object. Further, on the most object side of the third sub-group, there is provided an image blur correction lens group of positive refractive power for correcting the image blur when the optical system vibrates by moving in the direction perpendicular to the optical axis. ing. Since the negative group, which is the second partial group in the fourth lens group, is used as the focus group, there is a problem that the distortion aberration at the telephoto side close to the front becomes worse in the positive direction. Further, since the second lens group, which mainly controls zooming, has a high refractive power, there is a problem that the residual aberration of the second lens group is large and the sensitivity to manufacturing error is high.

The present invention has been made in view of the above problems, is a fixed length type during zooming and focusing, suppresses manufacturing error sensitivity, has a small image height change rate during wobbling, and is capable of zooming and focusing. An object of the present invention is to provide a variable power imaging optical system that has good optical performance over the entire area, has an image stabilizing function, and suppresses the weight of the image stabilizing lens group and the focus lens group.

A first aspect of the invention for solving the above-mentioned problems is, in order from the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a positive refractive power. , An aperture stop, a fourth lens unit having a positive refracting power, a fifth lens unit having a negative refracting power, a sixth lens unit having a positive refracting power, and a seventh lens unit having a negative refracting power, The first, fifth, and seventh lens groups are fixed with respect to the image plane, and the sixth lens group moves toward the object side along the optical axis when focusing from an object at infinity to a near object. A variable-magnification imaging optical system is used.

In the second invention, the second lens group comprises, in order from the object side to the image side, a second lens group consisting of a negative single lens convex to the object side and a second lens group having a negative refractive power. The air distance between the 2a lens group and the 2b lens group is the largest among the air distances forming the second lens group, and the focal length of the 2a lens group and the focal length of the 2nd lens group satisfy the following conditions. The variable power imaging optical system according to the first invention is characterized by satisfying the formula.
(1) 0.35<G2at/G2t<0.80
(2) 1.40<G2af/G2f<5.40
However, G2t: combined thickness of the second lens group G2at: air distance between the 2a lens group and the 2b lens group G2f: focal length of the second lens group G2af: focal length of the 2a lens group

A third aspect of the invention is characterized in that the sixth lens group moves toward the object at the time of focusing from an object at infinity to a near object, and satisfies the following conditional expression: The variable power imaging optical system described in the second aspect of the invention is used.
However, (3) 0.19<f6/ft<0.65
(4) 1.20<MR^2*(1-M6^2)<6.00
(5) 0.19<M6<0.75
ft: focal length when the object distance is infinity at the telephoto end f6: focal length of the sixth lens group G6 M6: lateral magnification of the sixth lens group G6 when the object distance is infinity MR: the object distance at infinity Lateral magnification of seventh lens group G7

A fourth invention is the variable power imaging optical system according to any one of the first to third inventions, characterized in that the seventh lens group satisfies the following conditional expression.
(6)-0.85<f7/ft<-0.17
Where f7: focal length of the seventh lens group ft: object distance at the telephoto end, focal length at infinity

In a fifth aspect of the present invention, the seventh lens group comprises, in order from the object side to the image side, a 7a lens group having negative refracting power and a 7b lens group having positive refracting power. The variable magnification imaging optical system according to any one of the first to fourth inventions is characterized in that image stabilization is performed by displacing the group in a direction perpendicular to the optical axis.

A sixth invention is the variable power imaging optical system according to any one of the second to fifth inventions, characterized in that the second lens group satisfies the following conditional expression.
(7)-8.0<(G2a2+G2a1)/(G2a2-G2a1)<-1.5
Where G2a1: radius of curvature of the 2a lens group on the object side G2a2: radius of curvature of the 2a lens group on the image side

According to the present invention, the total length is fixed during zooming and focusing, the sensitivity to manufacturing error is suppressed, the rate of change in image height during wobbling is small, and good optical performance is provided throughout zooming and focusing. Thus, it becomes possible to provide a variable power imaging optical system having an image stabilizing function and suppressing the weight of the image stabilizing lens group and the focus lens group.

It is a lens block diagram which concerns on Example 1 of the variable power imaging optical system of this invention. 6 is a longitudinal aberration diagram of the variable magnification imaging optical system of Example 1 when the wide-angle end is focused at infinity. FIG. 7 is a longitudinal aberration diagram of the variable power imaging optical system of Example 1 when the intermediate focal length is focused at infinity. FIG. 7 is a longitudinal aberration diagram of the variable magnification imaging optical system of Example 1 when the telephoto end is focused at infinity. FIG. 7 is a longitudinal aberration diagram of the variable power imaging optical system of Example 1 when focused at 1 m at the wide-angle end. FIG. 9 is a longitudinal aberration diagram of the variable magnification imaging optical system of Example 1 when the intermediate focal length is 1 m in focus. FIG. 9 is a longitudinal aberration diagram of the variable power imaging optical system of Example 1 when focused at 1 m at the telephoto end. FIG. FIG. 6 is a lateral aberration diagram at the time of wide angle end focusing on infinity of the variable power imaging optical system of Example 1; 9 is a lateral aberration diagram at the time of focusing on an intermediate focal length of the variable power imaging optical system of Example 1 at infinity. FIG. FIG. 9 is a lateral aberration diagram at the telephoto end of the variable magnification imaging optical system of Example 1 when focused on infinity. FIG. 9 is a lateral aberration diagram at the time of focusing at infinity at the wide-angle end of the variable power imaging optical system of Example 1 at the time of 0.4° vibration isolation. 9 is a lateral aberration diagram at 0.4° vibration isolation at the time of focusing on an intermediate focal length of the variable magnification imaging optical system of Example 1 at infinity. FIG. FIG. 9 is a lateral aberration diagram at the time of focusing at infinity at the telephoto end of the variable power imaging optical system of Example 1 at the time of 0.4° vibration isolation. It is a lens block diagram which concerns on Example 2 of the variable power imaging optical system of this invention. 16 is a longitudinal aberration diagram of the variable power imaging optical system of Example 2 at the wide-angle end when focused on infinity. FIG. 16 is a longitudinal aberration diagram of the variable magnification imaging optical system of Example 2 when the intermediate focal length is focused at infinity. FIG. FIG. 9 is a longitudinal aberration diagram at the telephoto end of the variable power imaging optical system of Example 2 when focused on infinity. 16 is a longitudinal aberration diagram of the variable power imaging optical system of Example 2 when focused at 1 m at the wide-angle end. FIG. FIG. 10 is a longitudinal aberration diagram of the variable power imaging optical system of Example 2 when focused at 1 m of the intermediate focal length. 16 is a longitudinal aberration diagram of the variable power imaging optical system of Example 2 when focused at 1 m at the telephoto end. FIG. FIG. 9 is a lateral aberration diagram at the time of wide-angle end focusing on infinity of the variable power imaging optical system of Example 2; FIG. 9 is a lateral aberration diagram at the time of focusing on an intermediate focal length of the variable power imaging optical system of Example 2 at infinity. FIG. 9 is a lateral aberration diagram at the telephoto end of the variable power imaging optical system of Example 2 when focused on infinity. 10 is a lateral aberration diagram at the time of focusing at infinity at the wide-angle end of the variable power imaging optical system of Example 2 at the time of 0.4° vibration isolation. FIG. FIG. 9 is a lateral aberration diagram at the time of focusing at infinity at the intermediate focal length of the variable power imaging optical system of Example 2 at the time of 0.4° vibration isolation. FIG. 9 is a lateral aberration diagram at the time of focusing at infinity at the telephoto end of the variable power imaging optical system of Example 2 at the time of 0.4° vibration isolation. It is a lens block diagram which concerns on Example 3 of the variable power imaging optical system of this invention. 16 is a longitudinal aberration diagram of the variable power imaging optical system of Example 3 when focused at infinity at the wide-angle end. FIG. 16 is a longitudinal aberration diagram of the variable magnification imaging optical system of Example 3 when the intermediate focal length is focused at infinity. FIG. FIG. 16 is a longitudinal aberration diagram at the telephoto end of the variable power imaging optical system of Example 3 when focused on infinity. 16 is a longitudinal aberration diagram of the variable power imaging optical system of Example 3 when focused at 1 m at the wide angle end. FIG. FIG. 16 is a longitudinal aberration diagram of the variable power imaging optical system of Example 3 when focused on the intermediate focal length of 1 m. 16 is a longitudinal aberration diagram of the variable power imaging optical system of Example 3 when focused at 1 m at the telephoto end. FIG. FIG. 16 is a lateral aberration diagram at the wide-angle end when focused on infinity, in the variable power imaging optical system of Example 3; FIG. 13 is a lateral aberration diagram at the time of focusing on an intermediate focal length of the variable power imaging optical system of Example 3 at infinity. FIG. 16 is a lateral aberration diagram at the telephoto end of the variable power imaging optical system of Example 3 when focused on infinity. FIG. 9 is a lateral aberration diagram at the time of focusing at infinity at the wide-angle end of the variable power imaging optical system of Example 3 at the time of 0.4° vibration isolation. FIG. 10 is a lateral aberration diagram at 0.4° vibration reduction at infinity focusing of the intermediate focal length of the variable power imaging optical system of Example 3. FIG. 9 is a lateral aberration diagram at the time of focusing at infinity at the telephoto end of the variable power imaging optical system of Example 3 at the time of 0.4° vibration isolation. It is a lens block diagram which concerns on Example 4 of the variable power imaging optical system of this invention. 16 is a longitudinal aberration diagram of the variable power imaging optical system of Example 4 when focused at infinity at the wide-angle end. FIG. 16 is a longitudinal aberration diagram of the variable magnification imaging optical system of Example 4 when the intermediate focal length is focused at infinity. FIG. 16 is a longitudinal aberration diagram of the variable power imaging optical system of Example 4 when focused at infinity at the telephoto end. FIG. 16 is a longitudinal aberration diagram of the variable power imaging optical system of Example 4 when focused at 1 m at the wide-angle end. FIG. FIG. 16 is a longitudinal aberration diagram of the variable power imaging optical system of Example 4 when focused on the intermediate focal length of 1 m. 16 is a longitudinal aberration diagram of the variable power imaging optical system of Example 4 when focused at 1 m at the telephoto end. FIG. FIG. 16 is a lateral aberration diagram at the time of wide-angle end focusing on infinity of the variable power imaging optical system of Example 4; FIG. 16 is a lateral aberration diagram at the time when the intermediate focal length of the variable power imaging optical system of Example 4 is focused at infinity. 16 is a lateral aberration diagram at the telephoto end of the variable-magnification imaging optical system of Example 4 upon focusing on infinity. FIG. FIG. 16 is a lateral aberration diagram at the time of focusing at infinity at the wide-angle end of the variable power imaging optical system of Example 4 at the time of 0.4° vibration isolation. FIG. 10 is a lateral aberration diagram at the time of 0.4° image stabilization when the intermediate focal length of the variable power imaging optical system of Example 4 is focused at infinity. FIG. 16 is a lateral aberration diagram at the time of focusing at infinity at the telephoto end of the variable power imaging optical system of Example 4 at the time of 0.4° vibration isolation. It is a lens block diagram which concerns on Example 5 of the variable power imaging optical system of this invention. 16 is a longitudinal aberration diagram of the variable magnification imaging optical system of Example 5 when the wide-angle end is focused at infinity. FIG. 16 is a longitudinal aberration diagram of the variable power imaging optical system of Example 5 when the intermediate focal length is focused at infinity. FIG. 16 is a longitudinal aberration diagram of the variable power imaging optical system of Example 5 when focused on infinity at the telephoto end. FIG. 16 is a longitudinal aberration diagram of the variable power imaging optical system of Example 5 when focused at 1 m at the wide-angle end. FIG. FIG. 16 is a longitudinal aberration diagram of the variable power imaging optical system of Example 5 when focused on the intermediate focal length of 1 m. 16 is a longitudinal aberration diagram of the variable power imaging optical system of Example 5 when focused at 1 m at the telephoto end. FIG. FIG. 16 is a lateral aberration diagram at the time of wide-angle end focusing on infinity of the variable magnification imaging optical system of Example 5; 19 is a lateral aberration diagram at infinity focusing of the intermediate focal length of the variable power imaging optical system of Example 5. FIG. FIG. 16 is a lateral aberration diagram at the telephoto end of the variable power imaging optical system of Example 5 when focused on infinity. 19 is a lateral aberration diagram at the time of focusing at infinity at the wide-angle end of the variable power imaging optical system of Example 5 at the time of 0.4° vibration isolation. FIG. FIG. 16 is a lateral aberration diagram at the time of focusing at infinity at the intermediate focal length of the variable power imaging optical system of Example 5 at the time of 0.4° vibration isolation. FIG. 16 is a lateral aberration diagram at the time of focusing at infinity at the telephoto end of the variable power imaging optical system of Example 5 at the time of 0.4° vibration isolation. It is a lens block diagram which concerns on Example 6 of the variable power imaging optical system of this invention. 16 is a longitudinal aberration diagram of the variable power imaging optical system of Example 6 when focused at infinity at the wide-angle end. FIG. 16 is a longitudinal aberration diagram of the variable power imaging optical system of Example 6 when focused on an intermediate focal length at infinity. FIG. 16 is a longitudinal aberration diagram of the variable power imaging optical system of Example 6 when focused on infinity at the telephoto end. FIG. 19 is a longitudinal aberration diagram of the variable power imaging optical system of Example 6 when focused at 1 m at the wide angle end. FIG. 16 is a longitudinal aberration diagram of the variable power imaging optical system of Example 6 when focused on the intermediate focal length of 1 m. 19 is a longitudinal aberration diagram of the variable power imaging optical system of Example 6 when focused at 1 m at the telephoto end. FIG. FIG. 16 is a lateral aberration diagram at the time of wide angle end focusing on infinity of the variable power imaging optical system of Example 6; 16 is a lateral aberration diagram at infinity focusing of the intermediate focal length of the variable power imaging optical system of Example 6. FIG. FIG. 16 is a lateral aberration diagram at the telephoto end of the variable-magnification imaging optical system of Example 6 upon focusing on infinity. 16 is a lateral aberration diagram at the time of focusing at infinity at the wide-angle end of the variable power imaging optical system of Example 6 at the time of 0.4° image stabilization. FIG. 19 is a lateral aberration diagram at the time of focusing at infinity at the intermediate focal length of the variable power imaging optical system of Example 6 at the time of 0.4° vibration isolation. 16 is a lateral aberration diagram at the time of focusing at infinity at the telephoto end of the variable power imaging optical system of Example 6 at the time of 0.4° vibration isolation. FIG. It is a lens block diagram which concerns on Example 7 of the variable power imaging optical system of this invention. 16 is a longitudinal aberration diagram of the variable power imaging optical system of Example 7 when focused at infinity at the wide-angle end. FIG. 16 is a longitudinal aberration diagram of the variable power imaging optical system of Example 7 when focused on an intermediate focal length at infinity. FIG. 16 is a longitudinal aberration diagram of the variable power imaging optical system of Example 7 when focused on infinity at the telephoto end. FIG. 19 is a longitudinal aberration diagram of the variable power imaging optical system of Example 7 when focused at 1 m at the wide-angle end. FIG. FIG. 19 is a longitudinal aberration diagram of the variable power imaging optical system of Example 7 when focused on the intermediate focal length of 1 m. 16 is a longitudinal aberration diagram of the variable power imaging optical system of Example 7 when focused at 1 m at the telephoto end. FIG. FIG. 19 is a lateral aberration diagram at the wide-angle end when focused on infinity, in the variable power imaging optical system of Example 7; FIG. 16 is a lateral aberration diagram at the time of focusing on an intermediate focal length of the variable power imaging optical system of Example 7 at infinity. FIG. 19 is a lateral aberration diagram at the telephoto end of the variable-magnification imaging optical system of Example 7 at the time of focusing at infinity. FIG. 19 is a lateral aberration diagram at the time of focusing at infinity at the wide-angle end of the variable power imaging optical system of Example 7 at the time of 0.4° vibration isolation. 19 is a lateral aberration diagram at the time of focusing at infinity at the intermediate focal length of the variable power imaging optical system of Example 7 at the time of 0.4° vibration isolation. FIG. FIG. 16 is a lateral aberration diagram at the time of focusing by infinity at the telephoto end of the variable power imaging optical system of Example 7 at the time of 0.4° vibration isolation.

The variable power imaging optical system according to the present invention, as shown in the lens configuration diagrams of the respective examples of FIGS. 1, 14, 27, 40, 53, 66, and 79, changes from the object side to the image side. In order of positive refractive power first lens group, negative refractive power second lens group, positive refractive power third lens group, aperture stop, positive refractive power fourth lens group, negative refractive power Of the fifth lens group, the sixth lens group of positive refractive power, and the seventh lens group of negative refractive power, the first, fifth, and seventh lens groups are fixed with respect to the image plane during zooming, When focusing from an object at infinity to a near object, the sixth lens group moves to the object side along the optical axis.

The first lens group having a positive refracting power and the second lens group having a negative refracting power increase the distance between the wide-angle end and the telephoto end, thereby increasing the distance between them. It has a scaling effect.

The third lens group having a positive refracting power emits the light flux diverged by the second lens group having a negative refracting power substantially in parallel and makes it enter the subsequent aperture stop. This makes it possible to reduce the exposure error with respect to the shift error of the aperture stop mechanism in the optical axis direction.

The fourth lens group having a positive refracting power receives an afocal light beam which is substantially parallel light by the third lens group having a positive refracting power arranged on the object side. By adjusting this distance, it becomes possible to adjust the astigmatism without deteriorating the spherical aberration.

The fifth lens group having a negative refractive power is an expansion system for the converging system from the first lens group to the fourth lens group, so that the system up to the fifth lens group has a telephoto system configuration. By doing so, the total length can be reduced.

The sixth lens group having a positive refractive power functions as a focus lens group. It also plays a role of compensating for the image plane during zooming from the wide-angle end to the telephoto end. Further, by making the convergent light incident on the sixth lens group, it is possible to suppress the variation of spherical aberration during focusing. When focusing from an object at infinity to a near object, the sixth lens group moves to the object side along the optical axis. When the diaphragm is regarded as the object point of the sixth lens group, the object point approaches the sixth lens group when focusing at a close distance. As a result, the incident angle of the chief ray incident on the sixth lens group becomes large. The third-order distortion aberration coefficient increases with the cube of the paraxial incident angle of the principal ray, so that the negative distortion aberration of the sixth lens group itself increases, which causes the entire telephoto end system at the infinite object distance. The positive distortion aberration tends to be corrected when focusing is performed at a close distance. Further, by making the convergent light incident on the subsequent lens group, it becomes possible to reduce the diameter of the image stabilizing group at the head of the subsequent lens group.

The seventh lens group having a negative refracting power makes it possible to make the entire system into a telephoto type and shorten the total length by making the magnification load of the magnifying system. Further, in order from the object side to the image side, it is composed of the 7a lens group having a negative refractive power and the 7b lens group having a positive refractive power, and the 7a lens group is displaced in a direction perpendicular to the optical axis. By doing so, it is performing anti-vibration.

The variable power imaging optical system according to the present invention is characterized by satisfying the following conditional expression. That is, the second lens group is composed of, in order from the object side to the image side, the 2a lens group consisting of a negative single lens convex to the object side and the 2b lens group having a negative refractive power, and The air distance between the 2a lens group and the second b lens group is the largest of the air distances forming the second lens group, and the focal length of the second a lens group and the focal length of the second lens group are as follows. It is characterized in that the conditional expression is satisfied.
(1) 0.35<G2at/G2t<0.80
(2) 1.40<G2af/G2f<5.40
However, G2t: combined thickness of the second lens group G2at: air gap between the second a lens group and the second b lens group G2f: focal length of the second lens group G2af: focal length of the second lens group

Conditional expression (1) defines a preferable range for the ratio of the combined thickness of the second lens group that mainly controls zooming and the air gap sandwiched between the second-a lens group and the second-b lens group. .. Since the second lens group has a relatively large refracting power in the entire optical system and a large movement at the time of zooming, defining the structure of the second lens group is not limited to that of the second lens group. This is important for reducing the burden of aberration and suppressing the sensitivity to manufacturing errors.

The reason for this is as follows. The paraxial refracting power of an optical system composed of two lens groups is such that the refracting power of the first lens group is φ1, the refracting power of the second lens group is φ2, and the distance between the first lens group and the second lens group is t. , If the refractive power of the entire system is φ,
φ=φ1+φ2-t・φ1・φ2 Reference formula (1)
Therefore, when φ1 and φ2<0, φ increases when t is increased. That is, if φ is constant, the refracting powers φ1 and φ2 of each lens group can be reduced, and the amount of aberration generation and the manufacturing error sensitivity can be reduced.

Further, by forming the second-a lens group as a negative single lens convex toward the object side, it becomes possible to reduce the incident angle to the second-a lens group, and reduce the amount of aberration generation and the sensitivity to manufacturing error. Is possible.

When the upper limit of conditional expression (1) is exceeded and the air gap between the 2a lens group and the 2b lens group becomes relatively large, the manufacturing error sensitivity of the second lens group becomes small, It is possible to reduce the residual aberration of the second lens group, and it is possible to achieve an optical system that is easy to manufacture. However, the combined thickness of the second lens group becomes large, which is disadvantageous for compactness. ..

On the other hand, when the air gap between the second-a lens group and the second-b lens group becomes relatively small beyond the lower limit of conditional expression (1), the combined thickness of the second lens group becomes small. , The moving space of the second lens unit for zooming can be reduced, and the overall length of the optical system can be easily made compact. However, since the refracting power of each of the second lens unit and the second lens unit is increased, the second lens unit is strengthened. Problems such as an increase in residual aberration of the lens group and an increase in manufacturing error sensitivity cannot be solved.

It is to be noted that, with regard to the conditional expression (1), it is desirable to limit the upper limit value to 0.71 and the lower limit value to 0.38, so that the above-described effect can be further ensured.

Further, the conditional expression (2), together with the conditional expression (1), defines a preferable range for the ratio of the refractive power of the second-a lens group and the refractive power of the second-lens group. It affects the residual aberration of the second lens group and the sensitivity to manufacturing error. The light ray that is incident on the second lens group is a convergent light ray because the first lens group has a positive refractive power, but the second lens group has a negative refractive power, and thus the second lens group has a negative refractive power. The angle of incidence on the group tends to be tight. The present invention weakens the refracting power of the second lens group, and in particular, weakens the refracting power of the 2a lens group, thereby relaxing the incident angle to the 2a lens group and reducing the amount of aberration generation and manufacturing error sensitivity. I was able to reduce it.

When the upper limit of conditional expression (2) is exceeded and the refracting power of the second lens group becomes relatively weak, in order to keep the refracting power of the second lens group at a predetermined value, Manufacturing error sensitivity is reduced, residual aberration of the second lens group can be reduced, and an optical system that is easy to manufacture can be achieved. However, the second a lens group and the second b lens group have The distance between the sandwiched air becomes large, and the combined thickness of the second lens group becomes large, which is disadvantageous for downsizing.

On the other hand, if the lower limit of conditional expression (2) is exceeded and the refracting power of the 2a lens group becomes relatively strong, the residual aberration of the 2nd lens group becomes large, and the problem of increased manufacturing error sensitivity is solved. Can not. Alternatively, when the refracting power of the second lens group becomes weak, the amount of movement of the second lens group due to zooming increases, and the total length increases.

It is to be noted that, with regard to the conditional expression (2), it is desirable to set the upper limit value to 3.63 and the lower limit value to 1.69, so that the above-described effect can be further ensured.

Further, it is desirable that the sixth lens group moves toward the object at the time of focusing from an object at infinity to an object at a short distance, and satisfies the following conditional expression.
(3) 0.19<f6/ft<0.65
(4) 1.20<MR^2*(1-M6^2)<6.00
(5) 0.19<M6<0.75
ft: focal length when the object distance is infinity at the telephoto end f6: focal length of the sixth lens group G6 M6: lateral magnification of the sixth lens group G6 when the object distance is infinity MR: the object distance at infinity Lateral magnification of seventh lens group G7

Conditional expression (3) defines the focal length of the sixth lens group, which is the focus lens group, and is a condition for realizing high-speed focusing operation and downsizing of the optical system.

If the focal length f6 of the sixth lens group G6 becomes longer than the upper limit of the conditional expression (3), the amount of extension for focusing becomes long, and the ability to approach the closest point becomes weak. In addition, a space for securing the amount of payout is required, which leads to an increase in the total length and is not preferable.

If the focal length f6 of the sixth lens group G6 becomes shorter than the lower limit of conditional expression (3), the amount of extension for focusing becomes too short, and the focus lens group is stopped at an accurate focus position. Becomes difficult, and it becomes difficult to suppress the fluctuation of spherical aberration during focusing.

In conditional expression (3), the upper limit value is further set to 0.44, and the lower limit value is further set to 0.30, whereby the above-described effect can be further ensured.

Conditional expression (4) drives and controls the sixth lens group G6, which is a focus lens group, within the focusing range during AF, and therefore the sixth lens group G6 and the magnification burden on and after the sixth lens group G6 are applied. This is a regulation condition and regulates the sensitivity of the image plane when the sixth lens group G6 moves during focusing. By properly defining this sensitivity, it becomes possible to drive and control the focus lens group within the focusing range during AF.

When the upper limit of conditional expression (4) is exceeded and the sensitivity of the image forming surface increases, the amount of movement of the focus lens group decreases, so even a slight movement of the focus lens group causes the image forming surface to move greatly, resulting in AF focusing. It becomes difficult to drive and control the sixth lens group G6 which is the focus lens group within the range.

If the lower limit of conditional expression (4) is exceeded and the sensitivity of the imaging surface decreases, the amount of movement of the focus lens group increases, and the space between the fifth lens group G5 and the sixth lens group G6 for focusing is increased. It must be ensured, and it becomes difficult to make the lens optical system compact. Further, since the fluctuation of the chief ray height of the focusing lens group due to the wobbling becomes large, the effect of suppressing the fluctuation of the image height becomes weak and it becomes difficult to suppress the fluctuation of the image height at the time of the wobbling.

In conditional expression (4), the upper limit value is further set to 3.62, and the lower limit value is further set to 1.68, whereby the above-described effect can be further ensured.

Conditional expression (5) is a condition for defining the lateral magnification of G6 of the sixth lens group that is the focus lens group at infinity, suppressing aberration fluctuations during focusing, and defining the amount of extension of the focus group. is there.

If the lateral magnification of the sixth lens group G6 at infinity approaches 1 beyond the upper limit of conditional expression (5), the amount of extension for focusing becomes large, and a space for securing the amount of extension is required. This is not preferable because it leads to an increase in the total length.

On the other hand, when the lateral magnification of the sixth lens group G6 at infinity is decreased below the lower limit of conditional expression (5), the light beam incident on the focus group approaches afocal, and further exceeds zero and becomes negative. Since the focus group becomes a real image system, the movement of the object point of the sixth lens group G6, which is the focus group when the whole system focuses at a close distance, becomes large, so that the aberration fluctuation when changing from infinity to a close distance It becomes difficult to suppress.

In conditional expression (5), the upper limit value is further set to 0.50, and the lower limit value is further set to 0.28, whereby the above-described effect can be further ensured.

Further, it is desirable that the seventh lens group satisfy the following conditional expression.
(6)-0.85<f7/ft<-0.17
Where f7: focal length of the seventh lens group ft: object distance at the telephoto end, focal length at infinity

Conditional expression (6) is a condition for defining the focal length of the seventh lens group, which is a fixed group, and making the magnification system burden the magnifying system, thereby making the entire system a telephoto type and shortening the overall length.

When the negative refractive power of the seventh lens group becomes strong beyond the upper limit of conditional expression (6), the conjugate length of the fixed group becomes short, so that the total length becomes small, but spherical aberration and field curvature are reduced. Are excessively generated, and positive distortion is increased, which makes it difficult to correct them.

On the other hand, when the lower limit of conditional expression (6) is exceeded and the negative refractive power of the seventh lens group becomes weak, the conjugate length of the fixed group becomes long, which undesirably increases the overall length. In addition, it becomes impossible to maintain the distance from the sixth lens group, which is the focus group.

In conditional expression (6), the upper limit value is further set to −0.27, and the lower limit value is further set to −0.61, so that the above-described effect can be further ensured.

Further, it is desirable that the second-a lens group satisfies the following conditional expression.
(7)-8.0<(G2a2+G2a1)/(G2a2-G2a1)<-1.5
Where G2a1: radius of curvature of the 2a lens group on the object side G2a2: radius of curvature of the 2a lens group on the image side

Conditional expression (7) defines the lens shape of the 2a lens group, that is, the so-called shape factor. The light beam incident on the second lens group is a convergent light beam because the first lens group has a positive refractive power, but the second a lens group has a negative refractive power, and thus the second a lens element has a negative refractive power. When the radius of curvature on the object side of the group is negative, the incident angle becomes tight. In order to reduce the incident angle, it is essential that the radius of curvature of the second-a lens unit on the object side is positive.

If the shape factor of the second-a lens group approaches -1 beyond the upper limit of the conditional expression (7), the lens shape approaches a plano-concave lens, and the incident angle to the second-a lens group becomes tight, which is not preferable. ..

On the other hand, if the shape factor of the second-a lens group becomes large in the negative direction beyond the lower limit of the conditional expression (7), the negative refraction of the second-a lens group is combined with the conditional expression (2). Since the force becomes weak, the air gap between the 2a-th lens group and the 2b-th lens group becomes too wide, and the total length becomes large, which is not preferable.

In conditional expression (7), by setting the upper limit value to −2.5 and the lower limit value to −6.0, the above-described effect can be further ensured.

Next, a lens configuration of each embodiment of the variable power imaging optical system according to the present invention will be described. In the following description, the lens configurations will be described in order from the object side to the image side. Ln is a symbol indicating the lens corresponding to the lens number n when the lenses are sequentially counted from the object side, and in the case of a cemented lens, the symbol is indicated for each of the lenses constituting the lens.

Next, numerical examples of each embodiment of the variable power imaging optical system according to the present invention and the values corresponding to the conditional expressions will be described.

In [Surface data], the surface number is the number of the lens surface or aperture stop counted from the object side, r is the radius of curvature of the lens surface, d is the distance between the lens surfaces, and nd is for the d line (wavelength 587.56 nm). The refractive index, νd, represents the Abbe number for the d-line (wavelength 587.56 nm).

The * (asterisk) attached to the surface number indicates that the lens surface shape is an aspherical surface. BF represents back focus.

The (stop) added to the surface number indicates that the aperture stop is located at that position. ∞ (infinity) is entered in the radius of curvature for a plane or an aperture stop.

In [Aspherical surface data], the value of each coefficient giving the aspherical surface shape of the lens surface marked with * in [Surface data] is shown. The shape of the aspherical surface is represented by the following formula. In the following equation, y is the displacement from the optical axis in the direction perpendicular to the optical axis, z is the displacement (sag amount) from the intersection of the aspherical surface and the optical axis in the optical axis direction, and the radius of curvature of the reference spherical surface is r, The conic coefficient is represented by K. The fourth, sixth, eighth, and tenth-order aspherical surface coefficients are represented by A4, A6, A8, and A10, respectively.

[Various data] shows values such as the zoom ratio and the focal length in each focal length state.

[Variable distance data] shows the variable distance and the value of BF in each focal length state.

In [lens group data], the surface number of the lens surface closest to the object forming each lens group and the focal length of the entire lens group are shown.

In each aberration diagram corresponding to each example, d, g, and C represent d line, g line, and C line, and ΔS and ΔM represent sagittal image plane and meridional image plane, respectively.

In all the values of the following specifications, the focal length f, the radius of curvature r, the lens surface distance d, and other units of length are millimeters (mm) unless otherwise specified. The system is not limited to this because the same optical performance can be obtained in the proportional enlargement and the proportional reduction.

1 is a lens configuration diagram of an image forming optical system according to a first embodiment of the present invention.

From the object side to the image side, in order from the first lens group having a positive refractive power, the second lens group having a negative refractive power, the third lens group having a positive refractive power, the aperture stop, and the fourth lens group having a positive refractive power. , A fifth lens unit having a negative refracting power, a sixth lens unit having a positive refracting power, and a seventh lens unit having a negative refracting power, and the first, fifth, and seventh lens units are arranged on the image plane during zooming. The sixth lens group is fixed to the object side and moves toward the object side along the optical axis during focusing from an object at infinity to a near object.

The first lens group G1 includes a cemented lens including a negative meniscus lens L1 having a convex surface directed toward the object side and a biconvex lens L2, and a positive meniscus lens L3 having a convex surface directed toward the object side.

The second lens group G2 is composed of, in order from the object side, a second lens group G2a having a negative refractive power and a second lens group G2b having a negative refractive power, and the second lens group G2a has a convex surface directed toward the object side. It is composed of a negative meniscus lens L4. The 2b-th lens group G2b includes a cemented lens including a biconcave lens L5, a positive meniscus lens L6 having a convex surface directed toward the object side, and a negative meniscus lens L7 having a concave surface directed toward the object side.

The third lens group G3 is composed of a biconvex lens L8.

The aperture stop is provided on the image side of the third lens group G3, and moves integrally with the third lens group G3 as the magnification changes.

The fourth lens group G4 includes a cemented lens including a negative meniscus lens L9 having a convex surface directed toward the object side and a positive meniscus lens L10 having a convex surface directed toward the object side.

The fifth lens group G5 includes a positive meniscus lens L11 having a convex surface directed toward the object side and a biconcave lens L12.

The sixth lens group G6 is composed of a cemented lens including a biconvex lens L13 and a negative meniscus lens L14 having a concave surface facing the object side.

The seventh lens group G7 is composed of, in order from the object side, a 7a lens group G7a having a negative refractive power and a 7b lens group G7b having a positive refractive power, and the 7a lens group G7a has a concave surface facing the object side. The cemented lens includes a positive meniscus lens L15 and a biconcave lens L16, and a biconcave lens L17. The 7bth lens group G7b includes a biconvex lens L18, a biconvex lens L19, and a negative meniscus lens L20 having a concave surface facing the object side. , A biconcave lens L21, a negative meniscus lens L22 having a concave surface facing the object side, and a positive meniscus lens L23 having a convex surface facing the object side and having an aspherical object side. Further, the 7a lens group G7a is displaced in the direction perpendicular to the optical axis to perform image stabilization.

Next, the various values of the variable power imaging optical system according to the first embodiment are shown below.
Numerical Example 1
Unit: mm
[Surface data]
Surface number rd nd vd
Object ∞ ∞
1 111.0608 1.7040 1.75520 27.53
2 73.1017 10.5748 1.49700 81.61
3 -346.4136 0.1504
4 59.2892 6.4151 1.43700 95.10
5 156.4073 (d5)
6 56.4127 0.9021 1.63854 55.45
7 28.7428 17.9554
8 -76.8907 0.9021 1.48749 70.44
9 35.0716 2.6445 1.84666 23.78
10 96.5282 2.1621
11 -59.3333 0.9021 1.77250 49.62
12 -725.1815 (d12)
13 225.0285 2.3555 1.80450 39.64
14 -110.1587 1.0024
15 (Aperture) ∞ (d15)
16 43.0010 0.9021 2.00100 29.13
17 26.5925 5.1120 1.59282 68.62
18 1002.3541 (d18)
19 41.1166 3.3579 1.91082 35.25
20 454.5676 0.3608
21 -546.2830 0.9021 1.80000 29.84
22 36.1148 (d22)
23 48.7645 5.4628 1.48749 70.44
24 -37.5281 0.8019 1.69895 30.05
25 -65.7444 (d25)
26 -386.7082 2.8066 1.84666 23.78
27 -38.5004 0.8019 1.59349 67.00
28 29.6196 2.9670
29 -131.2683 0.8019 1.80100 34.97
30 77.4218 1.4434
31 35.2327 7.0666 1.49700 81.61
32 -35.2327 0.1504
33 193.1536 7.5678 1.69895 30.05
34 -19.9970 0.9021 1.84666 23.78
35 -41.9786 0.1504
36 -68.5811 0.9021 1.72916 54.67
37 229.3887 6.0342
38 -24.2169 0.9021 1.83481 42.72
39 -258.5573 0.1504
40* 33.5789 4.9617 1.58913 61.25
41 213.5014 32.6725
42 ∞ 2.1000 1.51680 64.17
43 ∞ (BF)
Image plane ∞

[Aspherical data]
40 sides
K 0.00000
A4 -9.86860E-06
A6 1.44132E-08
A8 -3.96359E-11
A10 5.48186E-14

[Various data]
Zoom ratio 2.67
Wide-angle mid-telephoto focal length 72.50 118.21 193.90
F number 4.14 4.14 4.14
Full angle of view 2ω 33.45 20.49 12.47
Image height Y 21.63 21.63 21.63
Total lens length 201.53 201.53 201.53

[Variable interval data]
Wide-angle mid-telephoto
d0 ∞ ∞ ∞
d5 0.6745 19.9570 34.5080
d12 32.6306 17.6314 1.2229
d15 3.8290 1.5062 1.5035
d18 3.9693 2.0095 3.8691
d22 19.1237 16.4996 19.1064
d25 3.1687 5.7922 3.1859
BF 1.1808 1.1807 1.1807

Wide-angle mid-telephoto
d0 798.4724 798.4723 798.4724
d5 0.6745 19.9570 34.5080
d12 32.6306 17.6314 1.2229
d16 3.8290 1.5062 1.5035
d18 3.9693 2.0095 3.8691
d22 16.9538 11.1532 4.8329
d25 5.3386 11.1386 17.4594
BF 1.1808 1.1806 1.1808

[Lens group data]
Focal length of group start surface
G1 1 107.91
G2 6 -31.81
G3 13 92.22
G4 16 132.97
G5 19 -478.75
G6 23 67.63
G7 26 -61.86
G2a 6 -92.95
G2b 8 -59.30
G7a 26 -30.32
G7b 31 48.90

FIG. 14 is a lens configuration diagram of an image forming optical system according to a second embodiment of the present invention.

From the object side to the image side, in order from the first lens group having a positive refractive power, the second lens group having a negative refractive power, the third lens group having a positive refractive power, the aperture stop, and the fourth lens group having a positive refractive power. , A fifth lens unit having a negative refracting power, a sixth lens unit having a positive refracting power, and a seventh lens unit having a negative refracting power, and the first, fifth, and seventh lens units are arranged on the image plane during zooming. The sixth lens group is fixed to the object side and moves toward the object side along the optical axis during focusing from an object at infinity to a near object.

The first lens group G1 includes a cemented lens including a negative meniscus lens L1 having a convex surface directed toward the object side and a biconvex lens L2, and a positive meniscus lens L3 having a convex surface directed toward the object side.

The second lens group G2 is composed of, in order from the object side, a second lens group G2a having a negative refractive power and a second lens group G2b having a negative refractive power, and the second lens group G2a has a convex surface directed toward the object side. It is composed of a negative meniscus lens L4. The 2b-th lens group G2b includes a cemented lens including a biconcave lens L5, a positive meniscus lens L6 having a convex surface directed toward the object side, and a negative meniscus lens L7 having a concave surface directed toward the object side.

The third lens group G3 is composed of a biconvex lens L8.

The aperture stop is provided on the image side of the third lens group G3, and moves integrally with the third lens group G3 as the magnification changes.

The fourth lens group G4 includes a cemented lens including a negative meniscus lens L9 having a convex surface directed toward the object side and a positive meniscus lens L10 having a convex surface directed toward the object side.

The fifth lens group G5 includes a positive meniscus lens L11 having a convex surface directed toward the object side and a biconcave lens L12.

The sixth lens group G6 is composed of a cemented lens including a biconvex lens L13 and a negative meniscus lens L14 having a concave surface facing the object side.

The seventh lens group G7 is composed of, in order from the object side, a 7a lens group G7a having a negative refractive power and a 7b lens group G7b having a positive refractive power, and the 7a lens group G7a has a concave surface facing the object side. The cemented lens includes a positive meniscus lens L15 and a biconcave lens L16, and a biconcave lens L17. The 7bth lens group G7b includes a biconvex lens L18, a biconvex lens L19, and a negative meniscus lens L20 having a concave surface facing the object side. , A biconcave lens L21, a negative meniscus lens L22 having a concave surface facing the object side, and a positive meniscus lens L23 having a convex surface facing the object side and having an aspherical object side. Further, the 7a lens group G7a is displaced in the direction perpendicular to the optical axis to perform image stabilization.

Next, the following are the specifications of the variable power imaging optical system according to the second embodiment.
Numerical Example 2
Unit: mm
[Surface data]
Surface number rd nd vd
Object ∞ ∞
1 101.7607 1.7026 1.75520 27.53
2 65.7345 10.5661 1.49700 81.61
3 -250.7871 0.1502
4 51.5785 6.4098 1.43700 95.10
5 114.3649 (d5)
6 56.0323 0.9014 1.80610 33.27
7 23.8739 6.2391
8 -78.7396 0.9014 1.48749 70.44
9 27.4411 4.0562 1.84666 23.78
10 134.2158 3.3050
11 -36.3075 0.9014 1.77250 49.62
12 -79.8378 (d12)
13 224.8436 2.3536 1.80450 39.64
14 -110.0682 1.0015
15 (Aperture) ∞ (d15)
16 42.9656 0.9014 2.00100 29.13
17 26.5706 5.1078 1.59282 68.62
18 1001.5303 (d18)
19 41.0828 3.3551 1.91082 35.25
20 454.1940 0.3606
21 -545.8340 0.9014 1.80000 29.84
22 36.0851 (d22)
23 48.7244 5.4583 1.48749 70.44
24 -37.4973 0.8012 1.69895 30.05
25 -65.6904 (d25)
26 -386.3904 2.8043 1.84666 23.78
27 -38.4688 0.8012 1.59349 67.00
28 29.5952 2.9645
29 -131.1604 0.8012 1.80100 34.97
30 77.3582 1.4422
31 35.2038 7.0608 1.49700 81.61
32 -35.2038 0.1502
33 192.9949 7.5616 1.69895 30.05
34 -19.9805 0.9014 1.84666 23.78
35 -41.9441 0.1502
36 -68.5247 0.9014 1.72916 54.67
37 229.2002 6.0292
38 -24.1970 0.9014 1.83481 42.72
39 -258.3447 0.1502
40* 33.5513 4.9576 1.58913 61.25
41 213.3260 32.6457
42 ∞ 2.1000 1.51680 64.17
43 ∞ (BF)
Image plane ∞

[Aspherical data]
40 sides
K 0.00000
A4 -9.92595E-06
A6 1.41198E-08
A8 -4.23238E-11
A10 6.42943E-14

[Various data]
Zoom ratio 2.68
Wide-angle mid-telephoto focal length 72.50 118.67 193.98
F number 4.15 4.15 4.14
Full angle of view 2ω 33.92 20.60 12.56
Image height Y 21.63 21.63 21.63
Total lens length 196.11 196.11 196.11

[Variable interval data]
Wide-angle mid-telephoto
d0 ∞ ∞ ∞
d5 0.7612 19.5355 33.5940
d12 31.6310 17.1362 1.2219
d15 3.8258 1.5050 1.5023
d18 3.9661 2.0079 3.8659
d22 19.1079 16.4679 19.1869
d25 3.1661 5.8055 3.0871
BF 5.9575 5.9575 5.9584

Wide-angle mid-telephoto
d0 803.8872 803.8871 803.8862
d5 0.7612 19.5355 33.5940
d12 31.6310 17.1362 1.2219
d16 3.8258 1.5050 1.5023
d18 3.9661 2.0079 3.8659
d22 17.1202 11.4796 5.8620
d25 5.1539 10.7938 16.4120
BF 5.9574 5.9577 5.9585

[Lens group data]
Focal length of group start surface
G1 1 98.32
G2 6 -30.87
G3 13 92.14
G4 16 132.86
G5 19 -478.36
G6 23 67.57
G7 26 -61.81
G2a 6 -52.26
G2b 8 -94.08
G7a 26 -30.29
G7b 31 48.86

FIG. 27 is a lens configuration diagram of the image forming optical system according to the third embodiment of the present invention.

From the object side to the image side, in order from the first lens group having a positive refractive power, the second lens group having a negative refractive power, the third lens group having a positive refractive power, the aperture stop, and the fourth lens group having a positive refractive power. , A fifth lens unit having a negative refracting power, a sixth lens unit having a positive refracting power, and a seventh lens unit having a negative refracting power, and the first, fifth, and seventh lens units are arranged on the image plane during zooming. The sixth lens group is fixed to the object side and moves toward the object side along the optical axis during focusing from an object at infinity to a near object.

The first lens group G1 includes a cemented lens including a negative meniscus lens L1 having a convex surface directed toward the object side and a biconvex lens L2, and a positive meniscus lens L3 having a convex surface directed toward the object side.

The second lens group G2 is composed of, in order from the object side, a second lens group G2a having a negative refractive power and a second lens group G2b having a negative refractive power, and the second lens group G2a has a convex surface directed toward the object side. It is composed of a negative meniscus lens L4. The second-b lens group G2b is composed of a biconcave lens L5, a cemented lens including a positive meniscus lens L6 having a convex surface directed toward the object side, and a biconcave lens L7.

The third lens group G3 is composed of a biconvex lens L8.

The aperture stop is provided on the image side of the third lens group G3, and moves integrally with the third lens group G3 as the magnification changes.

The fourth lens group G4 includes a cemented lens including a negative meniscus lens L9 having a convex surface directed toward the object side and a positive meniscus lens L10 having a convex surface directed toward the object side.

The fifth lens group G5 includes a positive meniscus lens L11 having a convex surface directed toward the object side and a biconcave lens L12.

The sixth lens group G6 is composed of a cemented lens including a biconvex lens L13 and a negative meniscus lens L14 having a concave surface facing the object side.

The seventh lens group G7 is composed of, in order from the object side, a 7a lens group G7a having a negative refractive power and a 7b lens group G7b having a positive refractive power, and the 7a lens group G7a has a concave surface facing the object side. The cemented lens includes a positive meniscus lens L15 and a biconcave lens L16, and a biconcave lens L17. The 7bth lens group G7b includes a biconvex lens L18, a biconvex lens L19, and a negative meniscus lens L20 having a concave surface facing the object side. , A biconcave lens L21, a negative meniscus lens L22 having a concave surface facing the object side, and a positive meniscus lens L23 having a convex surface facing the object side and having an aspherical object side. Further, the 7a lens group G7a is displaced in the direction perpendicular to the optical axis to perform image stabilization.

Next, the following are the specifications of the variable power imaging optical system according to the third embodiment.
Numerical Example 3
Unit: mm
[Surface data]
Surface number rd nd vd
Object ∞ ∞
1 110.9696 1.7026 1.75520 27.53
2 73.0416 10.5661 1.49700 81.61
3 -346.1290 0.1502
4 65.1865 6.4098 1.43700 95.10
5 154.7626 (d5)
6 37.8414 0.9014 1.80611 40.73
7 27.0937 16.3681
8 -161.6665 0.9014 1.48749 70.44
9 27.3888 4.3929 1.84666 23.78
10 57.7810 2.7590
11 -58.1927 0.9014 1.77250 49.62
12 898.8382 (d12)
13 224.8436 2.3536 1.80450 39.64
14 -110.0682 1.0015
15 (Aperture ∞ (d15)
16 42.9657 0.9014 2.00100 29.13
17 26.5706 5.1078 1.59282 68.62
18 1001.5306 (d18)
19 41.0828 3.3551 1.91082 35.25
20 454.1941 0.3606
21 -545.8342 0.9014 1.80000 29.84
22 36.0851 (d22)
23 48.7245 5.4583 1.48749 70.44
24 -37.4973 0.8012 1.69895 30.05
25 -65.6904 (d25)
26 -386.3905 2.8043 1.84666 23.78
27 -38.4688 0.8012 1.59349 67.00
28 29.5952 2.9645
29 -131.1604 0.8012 1.80100 34.97
30 77.3582 1.4422
31 35.2038 7.0608 1.49700 81.61
32 -35.2038 0.1502
33 192.9950 7.5616 1.69895 30.05
34 -19.9805 0.9014 1.84666 23.78
35 -41.9441 0.1502
36 -68.5247 0.9014 1.72916 54.67
37 229.2003 6.0292
38 -24.1970 0.9014 1.83481 42.72
39 -258.3448 0.1502
40* 33.5513 4.9576 1.58913 61.25
41 213.3260 29.7391
42 ∞ 2.1000 1.51680 64.17
43 ∞ (BF)
Image plane ∞

[Aspherical data]
40 sides
K 0.00000
A4 -1.02110E-05
A6 1.75156E-08
A8 -4.79764E-11
A10 6.21487E-14

[Various data]
Zoom ratio 2.68
Wide-angle mid-telephoto focal length 72.50 118.13 193.95
F number 4.00 3.99 4.00
Full angle of view 2ω 33.22 20.36 12.38
Image height Y 21.63 21.63 21.63
Total lens length 200.60 200.60 200.60

[Variable interval data]
Wide-angle mid-telephoto
d0 ∞ ∞ ∞
d5 0.7612 21.1417 36.7324
d12 34.7694 18.6685 1.2219
d15 3.8258 1.5050 1.5023
d18 3.9661 2.0079 3.8659
d22 19.1080 16.4046 19.1739
d25 3.1661 5.8689 3.1002
BF 0.2946 0.2947 0.2953

Wide-angle mid-telephoto
d0 799.3985 799.3985 799.3979
d5 0.7612 21.1417 36.7324
d12 34.7694 18.6685 1.2219
d16 3.8258 1.5050 1.5023
d18 3.9661 2.0079 3.8659
d22 16.7686 10.6751 3.7874
d25 5.5055 11.5983 18.4867
BF 0.2946 0.2947 0.2951

[Lens group data]
Focal length of group start surface
G1 1 116.42
G2 6 -33.87
G3 13 92.14
G4 16 132.86
G5 19 -478.36
G6 23 67.57
G7 26 -61.81
G2a 6 -122.94
G2b 8 -54.96
G7a 26 -30.29
G7b 31 48.86

FIG. 40 is a lens configuration diagram of the image forming optical system according to the fourth embodiment of the present invention.

From the object side to the image side, in order from the first lens group having a positive refractive power, the second lens group having a negative refractive power, the third lens group having a positive refractive power, the aperture stop, and the fourth lens group having a positive refractive power. , A fifth lens unit having a negative refracting power, a sixth lens unit having a positive refracting power, and a seventh lens unit having a negative refracting power. The sixth lens group is fixed to the object side and moves toward the object side along the optical axis during focusing from an object at infinity to a near object.

The first lens group G1 includes a cemented lens including a negative meniscus lens L1 having a convex surface directed toward the object side and a biconvex lens L2, and a positive meniscus lens L3 having a convex surface directed toward the object side.

The second lens group G2 is composed of, in order from the object side, a second lens group G2a having a negative refractive power and a second lens group G2b having a negative refractive power, and the second lens group G2a has a convex surface directed toward the object side. It is composed of a negative meniscus lens L4. The 2b-th lens group G2b includes a cemented lens including a biconcave lens L5, a positive meniscus lens L6 having a convex surface directed toward the object side, and a negative meniscus lens L7 having a concave surface directed toward the object side.

The third lens group G3 is composed of a biconvex lens L8.

The aperture stop is provided on the image side of the third lens group G3, and moves integrally with the third lens group G3 as the magnification changes.

The fourth lens group G4 includes a cemented lens including a negative meniscus lens L9 having a convex surface directed toward the object side and a positive meniscus lens L10 having a convex surface directed toward the object side.

The fifth lens group G5 includes a positive meniscus lens L11 having a convex surface directed toward the object side and a biconcave lens L12.

The sixth lens group G6 is composed of a cemented lens including a biconvex lens L13 and a negative meniscus lens L14 having a concave surface facing the object side.

The seventh lens group G7 is composed of, in order from the object side, a 7a lens group G7a having a negative refractive power and a 7b lens group G7b having a positive refractive power, and the 7a lens group G7a has a concave surface facing the object side. The cemented lens includes a positive meniscus lens L15 and a biconcave lens L16, and a biconcave lens L17. The 7bth lens group G7b includes a biconvex lens L18, a biconvex lens L19, and a negative meniscus lens L20 having a concave surface facing the object side. , A biconcave lens L21, a biconcave lens L22, and a positive meniscus lens L23 having an aspherical surface on the object side with the convex surface facing the object side. Further, the 7a lens group G7a is displaced in the direction perpendicular to the optical axis to perform image stabilization.

Next, the values of specifications of the variable power imaging optical system according to Example 4 are shown below.
Numerical Example 4
Unit: mm
[Surface data]
Surface number rd nd vd
Object ∞ ∞
1 111.1168 1.7049 1.75520 27.53
2 73.1385 10.5802 1.49700 81.61
3 -346.5881 0.1504
4 59.3191 6.4183 1.43700 95.10
5 156.4861 (d5)
6 40.2447 0.9026 1.80610 33.27
7 25.0514 11.3323
8 -148.4231 0.9026 1.48749 70.44
9 26.6560 4.0616 1.84666 23.78
10 71.3534 3.3094
11 -49.6215 0.9026 1.77250 49.62
12 -680.9412 (d12)
13 225.1418 2.3567 1.80450 39.64
14 -110.2142 1.0029
15 (Aperture) ∞ (d15)
16 43.0227 0.9026 2.00100 29.13
17 26.6058 5.1146 1.59282 68.62
18 1002.8590 (d18)
19 41.1373 3.3596 1.91082 35.25
20 454.7965 0.3610
21 -546.5581 0.9026 1.80000 29.84
22 36.1330 (d22)
23 44.9983 5.4656 1.48749 70.44
24 -27.0486 0.8023 1.69895 30.05
25 -48.7755 (d25)
26 -81.6613 2.6227 1.84666 23.78
27 -26.7123 0.8023 1.59349 67.00
28 36.8809 2.9685
29 -94.8464 0.8023 1.80100 34.97
30 75.8443 1.4441
31 34.3543 14.9390 1.49700 81.61
32 -38.2701 0.1504
33 59.0195 6.5978 1.69895 30.05
34 -23.3936 0.9026 1.84666 23.78
35 -64.2996 0.3287
36 -51.9365 0.9026 1.72916 54.67
37 221.8872 11.6776
38 -25.8522 0.9026 1.83481 42.72
39 381.8915 0.1504
40* 38.5889 9.7065 1.58913 61.25
41 -138.5520 25.3345
42 ∞ 2.1000 1.51680 64.17
43 ∞ (BF)
Image plane ∞

[Aspherical data]
40 sides
K 0.00000
A4 -5.76833E-06
A6 8.01478E-09
A8 -1.60060E-11
A10 1.44689E-14

[Various data]
Zoom ratio 2.68
Wide-angle mid-telephoto focal length 72.26 118.11 193.36
F number 4.16 4.15 4.15
Full angle of view 2ω 34.17 20.85 12.72
Image height Y 21.63 21.63 21.63
Total lens length 201.36 201.36 201.36

[Variable interval data]
Wide-angle mid-telephoto
d0 ∞ ∞ ∞
d5 0.7622 20.4768 35.3909
d12 33.4253 17.9953 1.2235
d15 3.8309 1.5070 1.5043
d18 3.9713 2.0105 3.8710
d22 14.2027 12.1292 14.2027
d25 2.1568 4.2304 2.1569
BF 0.1500 0.1501 0.1501

Wide-angle mid-telephoto
d0 798.6356 798.6356 798.6356
d5 0.7622 20.4768 35.3909
d12 33.4253 17.9953 1.2235
d15 3.8309 1.5070 1.5043
d18 3.9713 2.0105 3.8710
d22 12.5339 7.9515 3.0187
d25 3.8256 8.4081 13.3408
BF 0.1502 0.1500 0.1501

[Lens group data]
Focal length of group start surface
G1 1 107.96
G2 6 -32.57
G3 13 92.26
G4 16 133.04
G5 19 -478.99
G6 23 58.60
G7 26 -51.41
G2a 6 -84.56
G2b 8 -64.10
G7a 26 -26.69
G7b 31 43.95

FIG. 53 is a lens configuration diagram of an image forming optical system according to a fifth embodiment of the present invention.

From the object side to the image side, in order from the first lens group having a positive refractive power, the second lens group having a negative refractive power, the third lens group having a positive refractive power, the aperture stop, and the fourth lens group having a positive refractive power. , A fifth lens unit having a negative refracting power, a sixth lens unit having a positive refracting power, and a seventh lens unit having a negative refracting power, and the first, fifth, and seventh lens units are arranged on the image plane during zooming. The sixth lens group is fixed to the object side and moves toward the object side along the optical axis during focusing from an object at infinity to a near object.

The first lens group G1 includes a cemented lens including a negative meniscus lens L1 having a convex surface directed toward the object side and a biconvex lens L2, and a positive meniscus lens L3 having a convex surface directed toward the object side.

The second lens group G2 is composed of, in order from the object side, a second lens group G2a having a negative refractive power and a second lens group G2b having a negative refractive power, and the second lens group G2a has a convex surface directed toward the object side. It is composed of a negative meniscus lens L4. The 2b-th lens group G2b includes a cemented lens including a biconcave lens L5, a positive meniscus lens L6 having a convex surface directed toward the object side, and a negative meniscus lens L7 having a concave surface directed toward the object side.

The third lens group G3 is composed of a biconvex lens L8.

The aperture stop is provided on the image side of the third lens group G3, and moves integrally with the third lens group G3 as the magnification changes.

The fourth lens group G4 is composed of a cemented lens including a negative meniscus lens L9 having a convex surface directed toward the object side and a biconvex lens L10.

The fifth lens group G5 includes a positive meniscus lens L11 having a convex surface directed toward the object side and a negative meniscus lens L12 having a convex surface directed toward the object side.

The sixth lens group G6 is composed of a cemented lens including a biconvex lens L13 and a negative meniscus lens L14 having a concave surface facing the object side.

The seventh lens group G7 is composed of, in order from the object side, a 7a lens group G7a having a negative refractive power and a 7b lens group G7b having a positive refractive power, and the 7a lens group G7a has a concave surface facing the object side. The cemented lens includes a positive meniscus lens L15 and a biconcave lens L16, and a biconcave lens L17. The 7bth lens group G7b includes a biconvex lens L18, a biconvex lens L19, and a negative meniscus lens L20 having a concave surface facing the object side. A negative meniscus lens L21 having a concave surface facing the object side, a negative meniscus lens L22 having a concave surface facing the object side, and a positive meniscus lens L23 having a convex surface facing the object side. Further, the seventh-a lens group G7a is displaced in the direction perpendicular to the optical axis to perform image stabilization.

Subsequently, the various specifications of the variable power imaging optical system according to Example 5 are shown below.
Numerical Example 5
Unit: mm
[Surface data]
Surface number rd nd vd
Object ∞ ∞
1 111.4996 1.7107 1.75520 27.53
2 73.3905 10.6166 1.49700 81.61
3 -347.7821 0.1509
4 59.5235 6.4404 1.43700 95.10
5 157.0252 (d5)
6 40.3834 0.9057 1.80610 33.27
7 25.1377 11.3713
8 -148.9345 0.9057 1.48749 70.44
9 26.7478 4.0756 1.84666 23.78
10 71.5992 3.3208
11 -49.7924 0.9057 1.77250 49.62
12 -683.2872 (d12)
13 225.9175 2.3648 1.80450 39.64
14 -110.5939 1.0063
15 (Aperture) ∞ (d15)
16 43.4304 0.9057 2.00100 29.13
17 27.6721 5.1322 1.59282 68.62
18 -541.7930 (d18)
19 52.9918 3.3712 1.91082 35.25
20 166.1745 1.7092
21 1284.5288 0.9057 1.80000 29.84
22 43.0279 (d22)
23 62.0542 5.4844 1.48749 70.44
24 -46.9488 0.8051 1.69895 30.05
25 -83.0493 (d25)
26 -331.0637 2.8177 1.84666 23.78
27 -41.9781 0.8051 1.59349 67.00
28 40.0619 2.9787
29 -126.0625 0.8051 1.80100 34.97
30 82.1949 1.4491
31 35.8414 9.7980 1.49700 81.61
32 -33.0783 0.1509
33 321.2237 10.0342 1.69895 30.05
34 -21.9990 0.9057 1.84666 23.78
35 -49.4138 0.5072
36 -39.2668 0.9057 1.72916 54.67
37 -360.0812 5.8938
38 -22.9759 0.9057 1.83481 42.72
39 -48.5945 0.1509
40 44.7047 4.9813 1.58913 61.25
41 249.8810 21.5993
42 ∞ 2.1074 1.51680 64.17
43 ∞ (BF)
Image plane ∞

[Various data]
Zoom ratio 2.68
Wide-angle mid-telephoto focal length 72.50 130.40 194.00
F number 4.14 4.13 4.13
Full angle of view 2ω 34.10 18.95 12.70
Image height Y 21.63 21.63 21.63
Total lens length 208.71 208.71 208.71

[Variable interval data]
Wide-angle mid-telephoto
d0 ∞ ∞ ∞
d5 0.7648 23.7231 35.5159
d12 33.5435 14.8846 1.2277
d15 3.8441 1.5122 1.5095
d18 3.9850 2.0175 3.8844
d22 25.7351 20.7134 25.7157
d25 3.3789 8.3997 3.3983
BF 8.5724 8.5733 8.5724

Wide-angle mid-telephoto
d0 791.2925 791.2924 791.2924
d5 0.7648 23.7231 35.5159
d12 33.5435 14.8846 1.2277
d16 3.8441 1.5122 1.5095
d18 3.9850 2.0175 3.8844
d22 22.1246 10.1066 1.7655
d25 6.9894 19.0066 27.3486
BF 8.5724 8.5733 8.5724

[Lens group data]
Focal length of group start surface
G1 1 108.33
G2 6 -32.68
G3 13 92.58
G4 16 105.21
G5 19 -197.22
G6 23 85.91
G7 26 -118.33
G2a 6 -84.85
G2b 8 -64.32
G7a 26 -35.58
G7b 31 47.92

66 is a lens configuration diagram of an image forming optical system according to a sixth embodiment of the present invention.

From the object side to the image side, in order from the first lens group having a positive refractive power, the second lens group having a negative refractive power, the third lens group having a positive refractive power, the aperture stop, and the fourth lens group having a positive refractive power. , A fifth lens unit having a negative refracting power, a sixth lens unit having a positive refracting power, and a seventh lens unit having a negative refracting power, and the first, fifth, and seventh lens units are arranged on the image plane during zooming. The sixth lens group is fixed to the object side and moves toward the object side along the optical axis during focusing from an object at infinity to a near object.

The first lens group G1 includes a cemented lens including a negative meniscus lens L1 having a convex surface directed toward the object side and a biconvex lens L2, and a positive meniscus lens L3 having a convex surface directed toward the object side.

The second lens group G2 is composed of, in order from the object side, a second lens group G2a having a negative refractive power and a second lens group G2b having a negative refractive power, and the second lens group G2a has a convex surface directed toward the object side. It is composed of a negative meniscus lens L4. The 2b-th lens group G2b includes a cemented lens including a biconcave lens L5, a positive meniscus lens L6 having a convex surface directed toward the object side, and a negative meniscus lens L7 having a concave surface directed toward the object side.

The third lens group G3 is composed of a biconvex lens L8.

The aperture stop is provided on the image side of the third lens group G3, and moves integrally with the third lens group G3 as the magnification changes.

The fourth lens group G4 is composed of a cemented lens including a negative meniscus lens L9 having a convex surface directed toward the object side and a biconvex lens L10.

The fifth lens group G5 includes a positive meniscus lens L11 having a convex surface directed toward the object side and a biconcave lens L12.

The sixth lens group G6 is composed of a cemented lens including a biconvex lens L13 and a negative meniscus lens L14 having a concave surface facing the object side.

The seventh lens group G7 is composed of, in order from the object side, a 7a lens group G7a having a negative refractive power and a 7b lens group G7b having a positive refractive power, and the 7a lens group G7a has a concave surface facing the object side. The cemented lens includes a positive meniscus lens L15 and a biconcave lens L16, and a biconcave lens L17. The 7bth lens group G7b includes a biconvex lens L18, a biconvex lens L19, and a negative meniscus lens L20 having a concave surface facing the object side. , A biconcave lens L21, a negative meniscus lens L22 having a concave surface facing the object side, and a positive meniscus lens L23 having a convex surface facing the object side and having an aspherical object side. Further, the 7a lens group G7a is displaced in the direction perpendicular to the optical axis to perform image stabilization.

Next, the following are the specifications of the variable power imaging optical system according to Example 6.
Numerical Example 6
Unit: mm
[Surface data]
Surface number rd nd vd
Object ∞ ∞
1 110.8869 1.7013 1.75520 27.53
2 72.9872 10.5583 1.49700 81.61
3 -345.8710 0.1501
4 59.1964 6.4050 1.43700 95.10
5 156.1623 (d5)
6 40.1615 0.9007 1.80610 33.27
7 24.9996 11.3089
8 -148.1160 0.9007 1.48749 70.44
9 26.6008 4.0532 1.84666 23.78
10 71.2058 3.3026
11 -49.5188 0.9007 1.77250 49.62
12 -679.5324 (d12)
13 224.6760 2.3518 1.80450 39.64
14 -109.9862 1.0008
15 (Aperture) ∞ (d15)
16 39.7929 0.9007 2.00100 29.13
17 25.4554 5.1040 1.59282 68.62
18 -200.5164 (d18)
19 66.9425 1.9938 1.91082 35.25
20 321.3737 0.6288 1.00000 0.00
21 -180.7817 0.9007 1.80000 29.84
22 69.2506 (d22)
23 70.2323 5.4543 1.48749 70.44
24 -37.6316 0.8006 1.69895 30.05
25 -64.6406 (d25)
26 -386.1025 2.8022 1.84666 23.78
27 -38.4401 0.8006 1.59349 67.00
28 29.5732 2.9623
29 -131.0627 0.8006 1.80100 34.97
30 77.3006 1.4411
31 35.1776 7.0555 1.49700 81.61
32 -35.1776 0.1501
33 192.8511 7.5559 1.69895 30.05
34 -19.9656 0.9007 1.84666 23.78
35 -41.9 128 0.1501
36 -68.4736 0.9007 1.72916 54.67
37 229.0294 6.0247
38 -24.1789 0.9007 1.83481 42.72
39 -258.1522 0.1501
40* 33.5263 4.9539 1.58913 61.25
41 213.1670 30.3551
42 ∞ 2.1074 1.51680 64.17
43 ∞ (BF)
Image plane ∞

[Aspherical data]
40 sides
K 0.00000
A4 -1.12050E-05
A6 2.28367E-08
A8 -6.93799E-11
A10 9.63136E-14

[Various data]
Zoom ratio 2.68
Wide-angle mid-telephoto focal length 72.50 117.60 193.95
F number 4.15 4.11 4.14
Full angle of view 2ω 33.12 20.41 12.34
Image height Y 21.63 21.63 21.63
Total lens length 193.72 193.72 193.72

[Variable interval data]
Wide-angle mid-telephoto
d0 ∞ ∞ ∞
d5 0.7606 20.4344 35.3177
d12 33.3561 17.9581 1.2210
d15 3.8230 1.5039 1.5012
d18 3.9631 2.0064 3.8630
d22 19.1453 15.0714 19.1011
d25 3.0024 7.0744 3.0468
BF 0.3481 0.3504 0.3485

Wide-angle mid-telephoto
d0 806.2799 806.2795 806.2793
d5 0.7606 20.4344 35.3177
d12 33.3561 17.9581 1.2210
d16 3.8230 1.5039 1.5012
d18 3.9631 2.0064 3.8630
d22 16.5109 8.8545 2.3153
d25 5.6367 13.2914 19.8325
BF 0.3482 0.3504 0.3486

[Lens group data]
Focal length of group start surface
G1 1 107.74
G2 6 -32.50
G3 13 92.07
G4 16 82.39
G5 19 -208.66
G6 23 83.37
G7 26 -61.77
G2a 6 -84.39
G2b 8 -63.96
G7a 26 -30.27
G7b 31 48.82

FIG. 79 is a lens configuration diagram of an image forming optical system according to Example 7 of the present invention.

From the object side to the image side, in order from the first lens group having a positive refractive power, the second lens group having a negative refractive power, the third lens group having a positive refractive power, the aperture stop, and the fourth lens group having a positive refractive power. , A fifth lens unit having a negative refracting power, a sixth lens unit having a positive refracting power, and a seventh lens unit having a negative refracting power. The sixth lens group is fixed to the object side and moves toward the object side along the optical axis during focusing from an object at infinity to a near object.

The first lens group G1 includes a cemented lens including a negative meniscus lens L1 having a convex surface directed toward the object side and a biconvex lens L2, and a positive meniscus lens L3 having a convex surface directed toward the object side.

The second lens group G2 is composed of, in order from the object side, a second lens group G2a having a negative refractive power and a second lens group G2b having a negative refractive power, and the second lens group G2a has a convex surface directed toward the object side. It is composed of a negative meniscus lens L4. The 2b-th lens group G2b is composed of a biconcave lens L5, a positive meniscus lens L6 cemented lens with a convex surface facing the object side, and a negative meniscus lens L7 with a concave surface facing the object side.

The third lens group G3 is composed of a biconvex lens L8.

The aperture stop is provided on the image side of the third lens group G3 and moves integrally with the third lens group G3 as the magnification changes.

The fourth lens group G4 is composed of a cemented lens including a negative meniscus lens L9 having a convex surface directed toward the object side and a biconvex lens L10.

The fifth lens group G5 is composed of a biconvex lens L11 and a biconcave lens L12 on the object side.

The sixth lens group G6 is composed of a cemented lens including a biconvex lens L13 and a negative meniscus lens L14 having a concave surface facing the object side.

The seventh lens group G7 is composed of, in order from the object side, a 7a lens group G7a having a negative refractive power and a 7b lens group G7b having a positive refractive power, and the 7a lens group G7a has a concave surface facing the object side. The cemented lens includes a positive meniscus lens L15 and a biconcave lens L16, and a biconcave lens L17. The 7bth lens group G7b includes a biconvex lens L18, a biconvex lens L19, and a negative meniscus lens L20 having a concave surface facing the object side. , A biconcave lens L21, a negative meniscus lens L22 having a concave surface facing the object side, and a positive meniscus lens L23 having a convex surface facing the object side and having an aspherical object side. Further, the 7a lens group G7a is displaced in the direction perpendicular to the optical axis to perform image stabilization.

Next, the following are the specifications of the variable power imaging optical system according to Example 7.
Numerical Example 7
Unit: mm
[Surface data]
Surface number rd nd vd
Object ∞ ∞
1 111.1569 1.7055 1.75520 27.53
2 73.1649 10.5840 1.49700 81.61
3 -346.7131 0.1505
4 59.3405 6.4206 1.43700 95.10
5 156.5426 (d5)
6 40.2592 0.9029 1.80610 33.27
7 25.0605 11.3364
8 -148.4767 0.9029 1.48749 70.44
9 26.6656 4.0630 1.84666 23.78
10 71.3792 3.3106
11 -49.6394 0.9029 1.77250 49.62
12 -681.1868 (d12)
13 225.2230 2.3576 1.80450 39.64
14 -110.2540 1.0032
15 (Aperture) ∞ (d15)
16 60.6077 0.9029 2.00100 29.13
17 35.3647 5.1164 1.59282 68.62
18 -318.3229 (d18)
19 45.6946 3.6851 1.91082 35.25
20 -365.9192 0.3612
21 -123.2499 0.9029 1.80000 29.84
22 39.9208 20.4777
23 48.9552 5.4676 1.48749 70.44
24 -32.4081 0.8026 1.69895 30.05
25 -54.8727 (d25)
26 -387.0425 2.8090 1.84666 23.78
27 -38.5337 0.8026 1.59349 67.00
28 29.6452 2.9695
29 -131.3818 0.8026 1.80100 34.97
30 77.4888 1.4446
31 35.2632 7.0727 1.49700 81.61
32 -35.2632 0.1505
33 193.3206 7.5743 1.69895 30.05
34 -20.0143 0.9029 1.84666 23.78
35 -42.0 149 0.1505
36 -68.6404 0.9029 1.72916 54.67
37 229.5871 6.0394
38 -24.2378 0.9029 1.83481 42.72
39 -258.7808 0.1505
40* 33.6079 4.9659 1.58913 61.25
41 213.6860 32.5958
42 ∞ 2.1074 1.51680 64.17
43 ∞ (BF)
Image plane ∞

[Aspherical data]
40 sides
K 0.00000
A4 -9.46295E-06
A6 9.11007E-09
A8 -1.51677E-11
A10 1.39524E-14

[Various data]
Zoom ratio 2.68
Wide-angle mid-telephoto focal length 72.50 118.62 194.03
F number 4.14 4.14 4.13
Full angle of view 2ω 33.49 20.42 12.46
Image height Y 21.63 21.63 21.63
Total lens length 202.61 202.61 202.61

[Variable interval data]
Wide-angle mid-telephoto
d0 ∞ ∞ ∞
d5 0.7624 20.4842 35.4037
d12 33.4373 18.0018 1.2239
d15 3.8323 1.5075 1.5048
d18 3.9728 2.0113 3.8724
d22 20.4777 17.9854 20.4813
d25 5.3192 7.8115 5.3156
BF 1.5882 1.5887 1.5889

Wide-angle mid-telephoto
d0 797.3947 797.3943 797.3940
d5 0.7624 20.4842 35.4037
d12 33.4373 18.0018 1.2239
d16 3.8323 1.5075 1.5048
d18 3.9728 2.0113 3.8724
d22 18.4198 12.8003 6.5463
d25 7.3710 12.9835 19.2506
BF 1.6076 1.6308 1.5888


[Lens group data]
Focal length of group start surface
G1 1 108.00
G2 6 -32.58
G3 13 92.30
G4 16 145.38
G5 19 -356.10
G6 23 62.81
G7 26 -61.92
G2a 6 -84.59
G2b 8 -64.12
G7a 26 -30.35
G7b 31 48.94

The values corresponding to the conditional expressions corresponding to the respective examples are shown below.

Conditional expression/Example ex1 ex2 ex3
(1) 0.35<G2at/G2t<0.80 0.71 0.38 0.62
(2) 1.40<G2af/G2f<5.40 2.92 1.69 3.63
(3) 0.19<f6/ft<0.85 0.35 0.35 0.35
(4) 1.20<MR^2×(1-M6^2)<6.0 2.78 3.07 2.55
(5) 0.19 <M6 <0.75 0.36 0.34 0.38
(6) -0.85<F7/ft<-0.17 -0.32 -0.32 -0.32
(7) See below -3.08 -2.48 -6.04

Conditional expression/Example ex4 ex5
(1) 0.35<G2at/G2t<0.80 0.53 0.53
(2) 1.40<G2af/G2f<5.40 2.60 2.60
(3) 0.19<f6/ft<0.85 0.30 0.44
(4) 1.20<MR^2×(1-M6^2)<6.0 3.62 1.68
(5) 0.19<M6 <0.75 0.32 0.41
(6) -0.85<F7/ft<-0.17 -0.27 -0.61
(7) See below -4.30 -4.30

Conditional expression/Example ex6 ex7
(1) 0.35<G2at/G2t<0.80 0.53 0.53
(2) 1.40<G2af/G2f<5.40 2.60 2.60
(3) 0.19<f6/ft<0.85 0.43 0.32
(4) 1.20<MR^2×(1-M6^2)<6.0 2.26 2.96
(5) 0.19 <M6 <0.75 0.50 0.28
(6) -0.85<F7/ft<-0.17 -0.32 -0.32
(7) See below -4.30 -4.30

* Conditional expression (7) -8.0<(G2a2+G2a1)/(G2a2-G2a1)<-1.5

G1 1st lens group G2 2nd lens group G2a 2a lens group G2b 2b lens group G3 3rd lens group G4 4th lens group G5 5th lens group G6 6th lens group G7 7th lens group G7a 7a lens group G7b 7b Lens group S Aperture stop F Filter I Image plane

Claims (6)

In order from the object side to the image side, the first lens group having a positive refractive power, the second lens group having a negative refractive power, the third lens group having a positive refractive power, the aperture stop, and the positive refractive power A fourth lens group, a fifth lens group having a negative refractive power, a sixth lens group having a positive refractive power, and a seventh lens group having a negative refractive power,
At the time of zooming, the first, fifth and seventh lens units are fixed with respect to the image plane,
A variable power imaging optical system, wherein the sixth lens group moves toward the object side along the optical axis when focusing from an object at infinity to a near object. The second lens group includes, in order from the object side to the image side, a second lens group consisting of a negative single lens convex to the object side and a second lens group having a negative refractive power.
The air gap between the 2a-th lens group and the 2b-th lens group is the largest among the air gaps forming the second lens group,
2. The variable power imaging optical system according to claim 1, wherein the focal length of the second-a lens unit and the focal length of the second-lens unit satisfy the following conditional expression.
(1) 0.35<G2at/G2t<0.80
(2) 1.40<G2af/G2f<5.40
However, G2t: combined thickness of the second lens group G2at: air gap between the second a lens group and the second b lens group G2f: focal length of the second lens group G2af: focal length of the second lens group The variable power according to claim 1 or 2, wherein the sixth lens group moves toward the object at the time of focusing from an object at infinity to a near object and satisfies the following conditional expression. Imaging optics.
However, (3) 0.19<f6/ft<0.65
(4) 1.20<MR^2*(1-M6^2)<6.00
(5) 0.19<M6<0.75
ft: focal length when the object distance is infinity at the telephoto end f6: focal length of the sixth lens group G6 M6: lateral magnification of the sixth lens group G6 when the object distance is infinity MR: the object distance at infinity Lateral magnification of seventh lens group G7 4. The variable power imaging optical system according to claim 1, wherein the seventh lens group satisfies the following conditional expression.
(6)-0.85<f7/ft<-0.17
Where f7: focal length of the seventh lens group ft: object distance at the telephoto end, focal length at infinity The seventh lens group includes, in order from the object side to the image side, a 7a lens group having a negative refractive power and a 7b lens group having a positive refractive power, and the 7a lens group is perpendicular to the optical axis. The variable power imaging optical system according to any one of claims 1 to 4, wherein the image stabilization is performed by displacing in a direction. 6. The variable power imaging optical system according to claim 2, wherein the second-a lens group satisfies the following conditional expression.
(7)-8.0<(G2a2+G2a1)/(G2a2-G2a1)<-1.5
Where G2a1: radius of curvature of the 2a lens group on the object side G2a2: radius of curvature of the 2a lens group on the image side

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