JP7270970B2 - Variable-magnification imaging optical system with anti-vibration function - Google Patents

Description

The half angle of view at the telephoto end is as narrow as 3.5° or less, the total length is suppressed, the focus lens group is lightweight, enabling high-speed AF control, excellent anti-vibration performance, and the amount of peripheral light when the rear teleconverter is attached. To provide a variable-magnification imaging optical system that ensures

A variable-magnification imaging optical system with a narrow angle of view at the telephoto end has a long focal length, so the overall length of the optical system tends to be long, and the weight of the product tends to be heavy. In order to reduce the weight of the product, it is important not only to shorten the total length of the optical system, but also to reduce the size and weight of the lens groups such as the focus lens group and the anti-vibration lens group, which are driven by the actuators, to prevent the actuators from increasing in size.

2. Description of the Related Art In recent years, moving image shooting using an interchangeable lens camera has become popular. Autofocusing during moving image shooting often employs so-called contrast AF, in which a focus lens group is finely driven to detect a contrast peak. Therefore, in order to realize high-speed contrast AF, it is required to make the focus lens group sufficiently light.

Also, with a super-telephoto lens, camera shake and other vibrations tend to cause large image blurring, so it is necessary to improve image stabilization performance. If is increased, the outer diameter of the lens barrel becomes larger. Therefore, it is important not only to reduce the diameter of the anti-vibration lens group, but also to position the anti-vibration lens group so as to increase the capability of correcting the blurring of the captured image even if the amount of displacement of the anti-vibration lens group is small.

Also, super-telephoto lenses are generally compatible with rear teleconverters. In general, the rear teleconverter has a front lens part that protrudes from the surface that contacts the flange surface of the master lens. In order to be able to mount a rear teleconverter, it is necessary to secure a sufficient back focus. However, the front lens diameter of the rear teleconverter cannot be increased in order to fit the protruding portion of the rear teleconverter in the rear portion of the barrel of the master lens. Therefore, if the exit pupil position of the master lens is far from the image plane, light rays at peripheral angles of view emitted from the master lens are likely to be vignetted at the periphery of the rear teleconverter, resulting in a large decrease in the amount of peripheral light when the rear teleconverter is attached. . Therefore, in order to support the rear teleconverter, it is necessary to prevent the distance between the exit pupil and the image plane from becoming too long.

For example, the following patent documents can be cited as examples of variable-magnification imaging optical systems having a vibration reduction function.

JP 2017-223778 A JP 2017-120382 A JP 2018-169563 A

The variable magnification imaging optical system described in Patent Document 1 has a large number of focus lens groups, and the weight reduction of the focus group is insufficient.

The variable-magnification imaging optical system described in Patent Document 2 achieves weight reduction by constructing the focus lens group with a single lens, but the back focus is short and it is difficult to mount a rear teleconverter. .

The variable-magnification imaging optical system described in Patent Document 3 achieves weight reduction of the focus lens group by constructing the focus lens group with two lenses or less. It is difficult to reduce the weight of the lens barrel because the amount of movement of the lens group is large. Also, although a sufficient back focus is ensured, the distance from the exit pupil to the image plane is long, and when the rear teleconverter is attached, the amount of peripheral light decreases significantly.

The present invention has been made in view of such circumstances, and is excellent in that the half angle of view at the telephoto end is as narrow as about 3.5° or less, the overall length is suppressed, the focus lens group is light, and high-speed AF control is possible. It is an object of the present invention to provide a variable-magnification imaging optical system which has an improved image stabilization performance and secures peripheral light quantity when a rear teleconverter is mounted.

In order to achieve the above object, a first invention embodying the present invention comprises, in order from the object side, a first lens group G1 having a positive refractive power, a front lens group GF having a negative refractive power as a whole, and a consists of one intermediate lens group GM1 with positive refractive power, two intermediate lens groups GM2 with positive refractive power, and a rear lens group GR with negative refractive power as a whole, and the front lens group GF is one or It consists of two lens groups and includes a vibration reduction lens group with negative refractive power that corrects image blurring by moving in the direction perpendicular to the optical axis, and the first intermediate lens group GM1 includes two lenses with positive refractive power. An aperture stop S is provided closest to the image side, the intermediate two lens group GM2 is one lens group with positive refractive power, and is composed of two or less lenses, and the rear lens group GR is It is composed of two lens groups with negative refractive power, and when zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, and the first lens group G1 and the front side lens group GF are separated. The distance between the front side lens group GF and the middle lens group GM1 decreases, the distance between the middle lens group GM1 and the middle lens group GM2 changes, and the distance between the middle lens group GM2 and the middle lens group GM2 changes. The distance between the rear lens group GR decreases, and when the front lens group GF consists of two lens groups, the distance between the two lens groups in the front lens group GF changes, and the middle lens group GR changes. The distance between the two lens groups in GM1 varies, the distance between the two lens groups in the rear lens group GR varies, and the middle two lens groups GM2 move along the optical axis when focusing from infinity to close. A variable-magnification imaging optical system with image stabilizing function, which moves toward the object side by force, and satisfies the following conditional expression.
(1) 1.2<LT1m2t/f1m2t<1.55
(2) -0.7<fRw/fw<-0.3
however,
LT1m2t: Length from the most object-side surface to the image-side focal point of the combined system from the first lens group G1 to the intermediate two lens group GM2 at the telephoto end and infinity focus state f1m2t: Telephoto end, infinity Focal length fRw of the composite system from the first lens group G1 to the intermediate two lens group GM2 in the focused state: focal length fw of the rear lens group GR at the wide-angle end: wide-angle end, in the infinity focused state Let it be the focal length of the entire system.

In a second aspect of the present invention, the rear lens group GR moves the lens group on the object side toward the object side during zooming from the wide-angle end to the telephoto end. 2. A variable-magnification imaging optical system with a vibration reduction function according to claim 1, wherein the image-side group is fixed with respect to the image plane and satisfies the following conditional expression.
(3) 0.2<EXPt/LTt<0.4
however,
EXPt: length from the exit pupil to the image plane at the telephoto end and infinity focus state LTt: length from the most object-side surface of the optical system to the image plane at the telephoto end and infinity focus state.

In a third invention embodying the present invention, the front lens group GF comprises, in order from the object side, a GFp lens component with a positive refractive power, a GFn lens component with a negative refractive power, and a vibration reduction lens group with a negative refractive power. wherein the GFp lens component and the GFn lens component are separated by an air gap, the GFp lens component and the GFn lens component do not include an air gap inside, and satisfy the following conditional expression: 3. A variable-magnification imaging optical system with a vibration reduction function according to claim 1.
(4) 0.7<|LTFpnt/fFpnt|<0.95
however,
LTFpnt: Length from the most object side surface to the image side focal point of the composite system of the GFp lens component and the GFn lens component at the telephoto end fFpnt: The focal length of the composite system of the GFp lens component and the GFn lens component at the telephoto end .

A fourth aspect of the present invention is characterized in that at least part of the front lens group GF is fixed with respect to the image plane during zooming from the wide-angle end to the telephoto end. 4. A variable-magnification imaging optical system having an anti-vibration function according to any one of 1 to 3.

The half angle of view at the telephoto end is as narrow as 3.5° or less, the total length is suppressed, the focus lens group is lightweight, enabling high-speed AF control, excellent anti-vibration performance, and the amount of peripheral light when the rear teleconverter is attached. It is possible to provide a variable-magnification imaging optical system that ensures the

It is a lens configuration diagram according to Example 1 of the imaging optical system of the present invention. 4 is a longitudinal aberration diagram of the imaging optical system of Example 1 at the wide-angle end and in focus at infinity; FIG. FIG. 10 is a longitudinal aberration diagram of the imaging optical system of Example 1 at an intermediate focal length and infinity focusing; 4 is a longitudinal aberration diagram of the imaging optical system of Example 1 at the telephoto end and in focus at infinity. FIG. 4 is a lateral aberration diagram of the imaging optical system of Example 1 at the wide-angle end and in focus at infinity. FIG. 4 is a lateral aberration diagram of the imaging optical system of Example 1 at an intermediate focal length and infinity focusing; FIG. 4 is a lateral aberration diagram of the imaging optical system of Example 1 at the telephoto end and in focus at infinity. FIG. FIG. 10 is a lateral aberration diagram of the imaging optical system of Example 1 at the wide-angle end and at the time of focusing at infinity with vibration reduction of 0.5°; FIG. 10 is a lateral aberration diagram of the image forming optical system of Example 1 when image stabilization is performed by 0.5° at an intermediate focal length and infinity focusing; FIG. 10 is a lateral aberration diagram of the imaging optical system of Example 1 when vibration is reduced by 0.5° at the telephoto end and at the time of focusing at infinity; It is a lens block diagram concerning Example 2 of the imaging optical system of this invention. FIG. 10 is a longitudinal aberration diagram of the imaging optical system of Example 2 at the wide-angle end and in focus at infinity; FIG. 10 is a longitudinal aberration diagram of the imaging optical system of Example 2 at an intermediate focal length and infinity focusing; FIG. 10 is a longitudinal aberration diagram of the imaging optical system of Example 2 at the telephoto end and in focus at infinity; FIG. 11 is a lateral aberration diagram of the imaging optical system of Example 2 at the wide-angle end and in focus at infinity; FIG. 10 is a lateral aberration diagram of the imaging optical system of Example 2 at an intermediate focal length and infinity focusing; FIG. 10 is a lateral aberration diagram of the imaging optical system of Example 2 at the telephoto end and in focus at infinity; FIG. 10 is a lateral aberration diagram of the image forming optical system of Example 2 at the wide-angle end and at the time of focusing at infinity when vibration is reduced by 0.5°; FIG. 10 is a lateral aberration diagram of the image forming optical system of Example 2 when image stabilization is performed by 0.5° at an intermediate focal length and focusing at infinity; FIG. 10 is a lateral aberration diagram of the imaging optical system of Example 2 at the telephoto end and at the time of focusing at infinity when vibration is reduced by 0.5°; It is a lens block diagram concerning Example 3 of the imaging optical system of this invention. FIG. 10 is a longitudinal aberration diagram of the imaging optical system of Example 3 at the wide-angle end and in focus at infinity; FIG. 10 is a longitudinal aberration diagram of the imaging optical system of Example 3 at an intermediate focal length and infinity focusing; FIG. 11 is a longitudinal aberration diagram of the imaging optical system of Example 3 at the telephoto end and in focus at infinity. FIG. 11 is a lateral aberration diagram of the imaging optical system of Example 3 at the wide-angle end and in focus at infinity; FIG. 10 is a lateral aberration diagram of the imaging optical system of Example 3 at an intermediate focal length and infinity focusing; FIG. 11 is a lateral aberration diagram of the imaging optical system of Example 3 at the telephoto end and in focus at infinity; FIG. 11 is a lateral aberration diagram of the image forming optical system of Example 3 at the wide-angle end and at the time of focusing at infinity when vibration is reduced by 0.5°; FIG. 10 is a lateral aberration diagram of the image forming optical system of Example 3 when image stabilization is performed by 0.5° at an intermediate focal length and focusing at infinity; FIG. 10 is a lateral aberration diagram of the imaging optical system of Example 3 at the telephoto end and at the time of focusing at infinity when vibration is reduced by 0.5°; It is a lens block diagram concerning Example 4 of the imaging optical system of this invention. FIG. 12 is a longitudinal aberration diagram of the imaging optical system of Example 4 at the wide-angle end and in focus at infinity; FIG. 12 is a longitudinal aberration diagram of the imaging optical system of Example 4 at an intermediate focal length and infinity focusing; FIG. 11 is a longitudinal aberration diagram of the imaging optical system of Example 4 at the telephoto end and in focus at infinity. FIG. 11 is a lateral aberration diagram of the imaging optical system of Example 4 at the wide-angle end and in focus at infinity; FIG. 11 is a lateral aberration diagram of the imaging optical system of Example 4 at an intermediate focal length and infinity focusing; FIG. 11 is a lateral aberration diagram of the imaging optical system of Example 4 at the telephoto end and in focus at infinity; FIG. 10 is a lateral aberration diagram of the imaging optical system of Example 4 at the wide-angle end and at the time of focusing at infinity when vibration is reduced by 0.5°; FIG. 11 is a lateral aberration diagram of the image forming optical system of Example 4 when the image is focused at an intermediate focal length and infinity, and vibration is reduced by 0.5°; FIG. 11 is a lateral aberration diagram of the imaging optical system of Example 4 at the telephoto end and at the time of focusing at infinity with vibration reduction of 0.5°; It is a lens block diagram concerning Example 5 of the imaging optical system of this invention. FIG. 12 is a longitudinal aberration diagram of the imaging optical system of Example 5 at the wide-angle end and in focus at infinity; FIG. 12 is a longitudinal aberration diagram of the imaging optical system of Example 5 at an intermediate focal length and infinity focusing; FIG. 12 is a longitudinal aberration diagram of the imaging optical system of Example 5 at the telephoto end and in focus at infinity. FIG. 11 is a lateral aberration diagram of the imaging optical system of Example 5 at the wide-angle end and in focus at infinity; FIG. 12 is a lateral aberration diagram of the imaging optical system of Example 5 at an intermediate focal length and infinity focusing; FIG. 12 is a lateral aberration diagram of the imaging optical system of Example 5 at the telephoto end and in focus at infinity; FIG. 11 is a lateral aberration diagram of the image forming optical system of Example 5 at the wide-angle end and at the time of focusing at infinity when vibration is reduced by 0.5°; FIG. 12 is a lateral aberration diagram of the image forming optical system of Example 5 when image stabilization is performed by 0.5° at an intermediate focal length and focusing at infinity; FIG. 12 is a lateral aberration diagram of the image forming optical system of Example 5 when vibration is reduced by 0.5° at the telephoto end and at the time of focusing at infinity; It is a lens block diagram concerning Example 6 of the imaging optical system of this invention. FIG. 12 is a longitudinal aberration diagram of the imaging optical system of Example 6 at the wide-angle end and in focus at infinity. FIG. 11 is a longitudinal aberration diagram of the imaging optical system of Example 6 at an intermediate focal length and infinity focusing; FIG. 12 is a longitudinal aberration diagram of the imaging optical system of Example 6 at the telephoto end and in focus at infinity. FIG. 12 is a lateral aberration diagram of the imaging optical system of Example 6 at the wide-angle end and in focus at infinity; FIG. 12 is a lateral aberration diagram of the imaging optical system of Example 6 at an intermediate focal length and infinity focusing; FIG. 11 is a lateral aberration diagram of the imaging optical system of Example 6 at the telephoto end and in focus at infinity; FIG. 11 is a lateral aberration diagram of the image forming optical system of Example 6 at the wide-angle end and at the time of focusing at infinity with vibration reduction of 0.5°; FIG. 11 is a lateral aberration diagram of the image forming optical system of Example 6 when image stabilization is performed by 0.5° at an intermediate focal length and focusing at infinity; FIG. 11 is a lateral aberration diagram of the imaging optical system of Example 6 when the telephoto end and infinity focus are corrected by 0.5°; It is a lens configuration diagram according to Example 7 of the imaging optical system of the present invention. FIG. 12 is a longitudinal aberration diagram of the imaging optical system of Example 7 at the wide-angle end and in focus at infinity; FIG. 12 is a longitudinal aberration diagram of the imaging optical system of Example 7 at an intermediate focal length and infinity focusing; FIG. 11 is a longitudinal aberration diagram of the imaging optical system of Example 7 at the telephoto end and in focus at infinity. FIG. 20 is a lateral aberration diagram of the imaging optical system of Example 7 at the wide-angle end and in focus at infinity; FIG. 12 is a lateral aberration diagram of the imaging optical system of Example 7 at an intermediate focal length and infinity focusing; FIG. 20 is a lateral aberration diagram of the imaging optical system of Example 7 at the telephoto end and in focus at infinity; FIG. 20 is a lateral aberration diagram of the image forming optical system of Example 7 at the wide-angle end and at the time of focusing at infinity when vibration is reduced by 0.5°; FIG. 12 is a lateral aberration diagram of the image forming optical system of Example 7 when image stabilization is performed by 0.5° at an intermediate focal length and focusing at infinity; FIG. 20 is a lateral aberration diagram of the image forming optical system of Example 7 when vibration is reduced by 0.5° at the telephoto end and at the time of focusing at infinity;

As can be seen from the lens configuration diagrams shown in FIGS. 1, 11, 21, 31, 41, 51, and 61, the image forming optical system of the present invention has, in order from the object side, first lenses with positive refractive power. 1 lens group G1, a front lens group GF having negative refractive power as a whole, an intermediate 1 lens group GM1 having positive refractive power as a whole, and an intermediate 2 lens group GM2 having positive refractive power as a whole, and having negative refractive power as a whole. It consists of the rear lens group of power.

The front lens group GF is composed of one or two lens groups, and includes a negative refractive power anti-vibration lens group that corrects image blurring by moving in a direction perpendicular to the optical axis. is composed of one or two lens groups with positive refractive power, and is provided with an aperture stop S closest to the image side, the intermediate two lens group GM2 is composed of two or less lenses, and the rear lens group GR is It consists of one or two lens groups with negative refractive power.

During zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, the distance between the first lens group G1 and the front lens group GF increases, and the distance between the front lens group GF and the intermediate lens group increases. The distance between the first lens group GM1 decreases, the distance between the first intermediate lens group GM1 and the second intermediate lens group GM2 changes, and the distance between the second intermediate lens group GM2 and the rear lens group GR decreases. During focusing from infinity to a short distance, the second intermediate lens group GM2 moves along the optical axis toward the object side.

During zooming from the wide-angle end to the telephoto end, the main zooming effect is obtained by increasing the distance between the positive first lens group G1 and the negative front lens group GF. In order to reduce the amount of movement of the first lens group G1 that accompanies zooming, it is preferable to use a reverse telephoto type refracting power arrangement at the wide-angle end and a telephoto type refracting power arrangement at the telephoto end.

Therefore, at the wide-angle end, the first lens group G1 with positive refractive power and the front lens group GF with negative refractive power are arranged close to each other so that their combined refractive power becomes negative. It is preferable to dispose a rear lens group having a positive refractive power as a whole at a position away from the synthesizing system of the group GF toward the image side. In the present invention, the rear lens group comprises, in order from the object side, an intermediate lens group GM1 with positive refractive power, an intermediate lens group GM2 with positive refractive power, and a rear lens group GR with negative refractive power.

At the wide-angle end, the middle two lens groups GM2 with positive refractive power and the rear lens group GR with negative refractive power are spaced apart from each other, so that the rear lens group has a telephoto-type refractive power arrangement at the wide-angle end. can shorten the total length of the optical system.

On the other hand, at the telephoto end, the middle two lens groups GM2 with positive refractive power and the rear lens group GR with negative refractive power are brought closer together, and furthermore the entire rear lens group is brought closer to the front lens group GF. The total length of the optical system at the telephoto end can be shortened by forming a telephoto-type refractive power arrangement between the first lens group G1 and the first lens group G1 by making the refractive power of the composite system after GF negative. The configuration described above is advantageous for reducing the amount of movement of the first lens group G1 while shortening the total length of the optical system at the wide-angle end.

Since the absolute value of the refractive power of the front lens group of negative refractive power, which is sandwiched between the first lens group G1 of positive refractive power and the intermediate lens group GM1 of positive refractive power, is large, displacement in the direction orthogonal to the optical axis It is easy to increase the displacement of the image in the direction perpendicular to the optical axis. In a telephoto variable-power imaging optical system in which the amount of image displacement due to camera shake tends to increase, there is a configuration in which all or part of the negative refractive power front lens group GF is displaced in the direction perpendicular to the optical axis to perform image stabilization. preferable.

In the present invention, it is preferable to move the second intermediate lens group GM2 along the optical axis toward the object side when focusing from infinity to a short distance. Since the diameter of the intermediate 2 lens group GM2 arranged on the image side of the intermediate 1 lens group GM1 is suppressed by converging the light flux in the intermediate 1 lens group GM1 having a positive refractive power, it is possible to use this as a focus lens group. It is advantageous for weight reduction.

In order to further reduce the weight of the focus lens group and realize high-speed AF control, it is preferable to configure the middle two lens group GM2 with two or less lenses. Recently, large format cameras with large sensors and excellent image quality have become popular. When the optical system is adapted to the large format, the principal ray at the peripheral angle of view passes through a high position in the optical system, so if the outer diameter of the lens is made smaller to reduce the weight, the reduction in the amount of peripheral light will increase. Therefore, in order to reduce the weight of the focus lens group while supporting the large format, it is required to configure the focus lens group with as few lenses as possible. Also, by reducing the number of focus lens groups, it is possible to secure a wide space for the focus lens group to move from infinity to short distances. If the amount of movement of the focus lens group can be increased, the refractive power of the focus lens group can be weakened, and the curvature of the lenses constituting the focus lens group can be relaxed to suppress the occurrence of aberration. This makes it possible to suppress deterioration in performance when the focus lens group is decentered due to manufacturing errors.

It is desirable that the intermediate two lens group GM2, which is a focus lens group, have a positive refractive power. It is assumed that the intermediate two lens group GM2 has negative refractive power. If the refracting power of the intermediate 2 lens group GM2 is weak, the amount of movement during focusing from infinity to a short distance becomes large, which is disadvantageous in shortening the total length of the optical system. However, if the negative refractive power of the composite system of the intermediate two lens group GM2 and the rear lens group GR becomes too strong, it becomes difficult to secure the back focus, so it is necessary to weaken the negative refractive power of the rear lens group GR. be. This weakens the effect of the rear lens group GR on zooming assistance when zooming from the wide-angle end to the telephoto end, and it is necessary to increase the amount of movement of the other groups during zooming to ensure high imaging performance over the entire zoom range. There is

However, if the amount of movement of the first lens group G1 is increased, the total length at the telephoto end becomes longer. Since it is necessary to secure a long distance from the GM1, the total length at the wide-angle end becomes long, and both lead to an increase in the weight of the lens barrel, which is not preferable. In addition, since the second intermediate lens group GM2 moves along the optical axis toward the image plane when focusing from infinity to a short distance, especially at the telephoto end where the amount of movement is large, the second intermediate lens group GM2 is shifted when focusing at infinity. and the rear lens group GR arranged on the image side thereof.

As a result, the distance between the second intermediate lens group GM2, which has a strong negative refractive power, and the image plane becomes long, and since the rear lens group GR has only a weak refractive power, the distance between the exit pupil and the image plane becomes long at the telephoto end. , when the rear teleconverter is attached, the peripheral luminous flux tends to be vignetting, making it difficult to secure the peripheral luminous intensity. If the middle two lens group GM2 has a positive refractive power, the negative refractive power of the rear lens group GR can be strengthened. It is advantageous to ensure

In order to realize a high-performance variable magnification imaging optical system with the above configuration, it is desirable to satisfy the following conditional expressions (1) and (2).
(1) 1.20<LT1m2t/f1m2t<1.55
(2) -0.7<fRw/fw<-0.3
however,
LT1m2t: Length from the most object-side surface to the image-side focal point of the combined system from the first lens group G1 to the intermediate two lens group GM2 at the telephoto end and infinity focus state f1m2t: Telephoto end, infinity Focal length fRw of the composite system from the first lens group G1 to the intermediate two lens group GM2 in the focused state: focal length fw of the rear lens group GR at the wide-angle end: wide-angle end, in the infinity focused state Let it be the focal length of the entire system.

Conditional expression (1) provides a telephoto ratio of the composite system from the first lens group G1 to the intermediate two lens group GM2 at the telephoto end and infinity focused state, while suppressing the total length of the optical system, and from infinity to short distances. It defines a preferable range for achieving high imaging performance over the entire focus range.

If the upper limit of conditional expression (1) is exceeded and the telephoto ratio of the composite system from the first lens group G1 to the middle two lens group GM2 at the telephoto end is increased, it is disadvantageous for shortening the total length of the optical system at the telephoto end. Further, when the focal length of the composite system from the first lens group G1 to the middle two lens group GM2 becomes short, the magnification of the rear lens group GR becomes large, and the middle two lens group GM2 moves along the optical axis during focusing. Aberration fluctuations when the lens is moved are magnified by the rear lens group GR, which is not preferable. In particular, reducing the number of focus lens groups to achieve high-speed AF increases aberration fluctuations when the focus lens group is moved along the optical axis. To realize this, it is necessary to reduce the magnification of the rear lens group GR.

On the other hand, when the lower limit of conditional expression 1 is exceeded and the telephoto ratio of the combined system from the first lens group G1 to the intermediate two lens group GM2 becomes small, the sensitivity to manufacturing errors increases, making it difficult to improve product performance. .

Further, it is preferable to set the lower limit to 1.25 and the upper limit to 1.52 for conditional expression (1), since the above effect can be more reliably achieved.

Conditional expression (2) defines a preferable range for suppressing the total length of the optical system while ensuring the back focus, with respect to the focal length ratio between the rear lens group GR and the entire system at the wide-angle end.

If the upper limit of conditional expression (2) is exceeded and the negative refractive power of the rear lens group becomes strong, the back focus at the wide-angle end becomes short, making it difficult to add an additional optical system such as a rear teleconverter to the image side of the optical system. Become.

On the other hand, when the lower limit of conditional expression (2) is exceeded and the negative refractive power of the rear lens group GR weakens, the object-side principal point of the rear lens group GR moves toward the image side, and the intermediate two lens groups at the wide-angle end The distance between GM2 and the rear lens group GR is narrowed. At the wide-angle end, the intermediate two lens groups GM2 with positive refractive power and the rear lens group GR with negative refractive power are arranged with a space therebetween to form a telescopic refractive power arrangement, and the total length of the combined system of these. can be shortened. If the distance between the middle two lens group GM2 and the rear lens group GR becomes narrower, the telephoto type refractive power arrangement weakens, making it difficult to shorten the total length.

In addition, in the variable-power imaging optical system of the present invention, the refractive power arrangement of the entire system is of a reverse telephoto type at the wide-angle end and of a telephoto type at the telephoto end. Effective for suppression. At the telephoto end, the refractive power of the composite system from the front lens group to the image plane side should be negative, and a telescopic refractive power arrangement should be provided between the first lens group G1 and the first lens group G1 having positive refractive power. When zooming from the wide-angle end to the telephoto end, the two intermediate lens groups GM2 and the rear lens group GR are brought closer to each other, so that the combined system of these becomes negative refractive power at the telephoto end, and the entire system is a strong telephoto type at the telephoto end. It is possible to facilitate the configuration of the refracting power arrangement of the lens and assist the zooming. If the distance between the two intermediate lens groups GM2 and the rear lens group GR is narrowed at the wide-angle end, it becomes difficult to change the distance there during zooming, and the effect of assisting zooming is weakened. As a result, the amount of movement of the first lens group G1 during zooming increases, degrading operability during zooming, and increasing the total length of the optical system at the telephoto end, increasing the weight of the lens barrel.

Further, it is preferable to set the lower limit to −0.65 and the upper limit to −0.35 for conditional expression (2) described above, because the above effects can be more reliably achieved.

Further, in the imaging optical system of the present invention, the rear lens group GR is composed of two groups of negative refractive power, and when zooming from the wide-angle end to the telephoto end, the lens group on the object side of the rear lens group GR moves toward the object side, and the lens group on the image side is preferably fixed with respect to the image plane.

By moving the negative refractive power lens group on the object side toward the object side during zooming from the wide-angle end to the telephoto end, the zooming action can be assisted and the amount of movement of the first lens group G1 can be reduced.

By fixing the negative refractive power lens group on the image side with respect to the image plane when zooming from the wide-angle end to the telephoto end, it is possible to suppress the distance from the exit pupil to the image plane from increasing over the entire zoom range. When an additional optical system is added to the image side of the magnifying optical system, it is possible to prevent the decrease in peripheral light quantity from becoming large.

The imaging optical system of the present invention preferably satisfies the following conditional expression (3).
(3) 0.20<EXPt/LTt<0.40
however,
EXPt: length from the exit pupil to the image plane at the telephoto end and infinity focus state LTt: length from the most object-side surface of the optical system to the image plane at the telephoto end and infinity focus state.

Conditional expression (3) defines a favorable condition for securing the amount of peripheral light while supporting the rear teleconverter with respect to the ratio of the length from the exit pupil to the image plane and the total length of the optical system at the telephoto end and in the infinity focused state. It is.

When the upper limit of conditional expression (3) is exceeded and the distance from the exit pupil to the image plane becomes long, when the rear teleconverter is attached, the amount of peripheral light decreases due to ray vignetting at peripheral angles of view.

On the other hand, when the lower limit of conditional expression (3) is exceeded and the distance from the exit pupil to the image plane becomes short, the principal ray passage position becomes high on the surface closest to the object side of the variable magnification optical system, making it difficult for the lower ray to pass through. As a result, vignetting becomes worse.

Further, setting the lower limit to 0.23 and the upper limit to 0.38 for the conditional expression (3) described above is preferable because the above effect can be more reliably achieved.

Further, in the imaging optical system of the present invention, the front lens group GF comprises, in order from the object side, a GFp lens component with positive refractive power, a GFn lens component with negative refractive power, and a vibration reduction lens group with negative refractive power. Preferably, the GFp lens component and the GFn lens component are separated by an air gap, and the GFp lens component and the GFn lens component do not contain an internal air gap.

A GFp lens component with positive refracting power and a GFn lens component with negative refracting power are placed in order from the object side with an air gap to form a telephoto refractive power arrangement, and a vibration reduction lens group is placed on the image side. By doing so, the light beam diameter of the anti-vibration lens group is suppressed, and the weight can be reduced.

The imaging optical system of the present invention preferably satisfies the following conditional expression (4).
(4) 0.70<|LTFpnt/fFpnt|<0.95
however,
LTFpnt: Length from the most object-side surface to the image-side focal point of the composite system of the GFp lens component and the GFn lens component at the telephoto end fFpnt: Length of the composite system of the GFp lens component and the GFn lens component at the telephoto end Let it be the focal length.

Conditional expression (4) defines a desirable condition for suppressing the ray diameter of the anti-vibration lens group with respect to the telephoto ratio of the composite system of the GFp lens component with positive refractive power and the GFn lens component with negative refractive power at the telephoto end. It is something to do.

When the upper limit of conditional expression (4) is exceeded and the telephoto ratio of the combined system of the GFp lens component and the GFn lens component increases, the light beam diameter cannot be suppressed, and the vibration reduction lens group becomes heavy. The larger the outer diameter, the heavier the weight of the product.

On the other hand, when the lower limit of conditional expression (4) is exceeded and the telephoto ratio of the combined system of the GFp lens component and the GFn lens component becomes small, the aberration fluctuation due to the manufacturing error of the GFp lens component and the GFn lens component becomes large during decentering. It becomes difficult to improve product performance.

Further, by limiting the lower limit to 0.74 and the upper limit to 0.92 for conditional expression (4) described above, the above effect can be more reliably achieved, which is preferable.

Further, in the imaging optical system of the present invention, it is desirable that at least part of the front lens group GF be fixed with respect to the image plane during zooming from the wide-angle end to the telephoto end. This simplifies the cam structure and reduces the weight of the lens barrel.

Further, in the imaging optical system of the present invention, the first intermediate lens group GM1 having a positive refractive power is divided into two with an air gap through which light rays pass substantially afocally. is preferably changed appropriately. As a result, the astigmatism of the entire optical system during zooming can be appropriately controlled without substantially affecting spherical aberration.

Further, when the intermediate two lens group GM2, which is the focus lens group, is composed of one convex lens, a diffractive optical element may be provided on either surface thereof. As a result, fluctuations in axial chromatic aberration during focusing can be suppressed, and a variable-magnification imaging optical system in which axial chromatic aberration is well corrected over the entire focusing range from infinity to short distances can be realized.

Next, a description will be given of the lens construction of an embodiment of the imaging optical system of the present invention.
In the following description, lens configurations are described in order from the object side to the image side.

In [surface data], the surface number is the number of the lens surface or aperture stop S counted from the object side, r is the radius of curvature of each surface, d is the distance between the surfaces, and nd is the d-line (wavelength λ = 587.56 nm). , and νd indicates the Abbe number for the d-line. BF represents back focus.

In (aperture stop) with a surface number, the radius of curvature ∞ (infinity) with respect to a plane or aperture stop S is written.

[Various data] shows values such as the focal length.

[Variable interval data] shows the variable interval and BF (back focus) values in each photographing distance state.

[Lens group data] indicates the number of the surface closest to the object side constituting each lens group and the combined focal length of the entire group.

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

In the aberration diagrams corresponding to each example, d, g, and C represent the d-line, g-line, and C-line, respectively, and .DELTA.S and .DELTA.M represent the sagittal image plane and the meridional image plane, respectively.

Furthermore, in the lens configuration diagrams shown in FIGS. 1, 11, 21, 31, 41, 51, and 61, S is the aperture stop, I is the image plane, and the dashed-dotted line passing through the center is the optical axis.

FIG. 1 is a lens configuration diagram of an imaging optical system according to Example 1 of the present invention.
A first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with negative refractive power, a fourth lens group G4 with positive refractive power, and a third lens group G4 with positive refractive power. It consists of five lens groups G5, a positive refractive power sixth lens group G6, a negative refractive power seventh lens group G7, and a negative refractive power eighth lens group G8.

When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, the second lens group G2 is fixed with respect to the image plane, and the third lens group G3 moves toward the image plane side. The fourth lens group G4 moves toward the object side, the fifth lens group G5 moves toward the object side, the sixth lens group G6 moves toward the object side, the seventh lens group G7 moves toward the object side, and the eighth lens group G7 moves toward the object side. The lens group G8 is fixed with respect to the image plane. An aperture diaphragm S is provided on the image side of the fifth lens group G5, and moves integrally with the fifth lens group G5 during zooming. When focusing from an infinite distance object to a short distance object, the sixth lens group G6 moves along the optical axis toward the object side.

In this embodiment, the front lens group GF is composed of a second lens group G2 and a third lens group G3. The first intermediate lens group GM1 is composed of a fourth lens group G4 and a fifth lens group G5, the second intermediate lens group GM2 is composed of a sixth lens group G6, and the rear lens group GR is composed of a seventh lens group G7 and an eighth lens group. It is composed of a lens group G8.

The first lens group G1 is composed of a cemented lens composed of a negative meniscus lens L1 having a convex surface facing the object side and a biconvex lens L2, and a biconvex lens L3.

The second lens group G2 is composed of a positive meniscus lens L4 having a convex surface facing the object side, and a cemented lens composed of a biconvex lens L5 and a biconcave lens L6.

The third lens group G3 is composed of a negative meniscus lens L7 having a convex surface facing the object side, and a cemented lens composed of a biconcave lens L8 and a biconvex lens L9. Image stabilization is performed by displacing the third lens group G3 in the direction perpendicular to the optical axis.

The fourth lens group G4 is composed of a biconvex lens L10, a cemented lens composed of a biconvex lens L11 and a negative meniscus lens L12 having a concave surface facing the object side.

The fifth lens group G5 includes a cemented lens composed of a positive meniscus lens L13 having a convex surface facing the object side, a negative meniscus lens L14 having a convex surface facing the object side, and a positive meniscus lens L15 having a convex surface facing the object side. It is composed of a negative meniscus lens L16 with a convex surface on the side and a biconvex lens L17.

The sixth lens group G6 is composed of a biconvex lens L18.

The seventh lens group G7 is composed of a negative meniscus lens L19 having a convex surface facing the object side, and a cemented lens composed of a biconcave lens L20 and a biconvex lens L21.

The eighth lens group G8 is composed of a negative meniscus lens L22 having a concave surface facing the object side.

Next, the specification values of the variable-magnification imaging optical system having the image stabilization function according to the first embodiment are shown below.
Numerical example 1
Unit: mm
[Surface data]
Face number rd nd vd
1 269.0618 2.0000 1.80420 46.50
2 100.3485 7.3530 1.49700 81.61
3 -1000.0000 0.1500
4 103.6699 6.9042 1.43700 95.10
5-1000.0000 (d5)
6 67.2136 3.6188 1.72047 34.71
7 283.3122 8.9336
8 117.0912 2.2287 1.56732 42.84
9 -537.1145 0.9000 1.91082 35.25
10 55.8686 (d10)
11 999.7824 0.9000 1.77250 49.62
12 58.5400 2.8984
13 -47.3445 0.9000 1.72916 54.67
14 70.3633 3.5000 1.84666 23.78
15 -536.3692 (d15)
16 251.0393 2.5660 1.69680 55.46
17 -94.2157 0.1500
18 70.2602 4.7971 1.58144 40.89
19 -47.7850 0.9000 2.05090 26.94
20 -286.8401 (d20)
21 30.1802 3.3204 1.69895 30.05
22 76.6145 0.5808
23 45.2280 0.9000 1.90043 37.37
24 21.3401 3.6409 1.59410 60.47
25 44.8198 1.4528
26 65.3065 0.9000 2.00100 29.13
27 34.0953 2.1662
28 1000.0000 2.5378 1.59282 68.63
29 -61.7873 2.3750
30 (Aperture) ∞ (d30)
31 46.0464 2.7485 1.59349 67.00
32 -1000.0000 (d32)
33 142.6963 0.9000 2.00100 29.13
34 36.9292 3.2506
35 -50.0947 0.9000 1.55032 75.50
36 44.1698 5.1303 1.78880 28.43
37 -57.9789 (d37)
38 -40.1895 1.0000 2.05090 26.94
39 -59.1319 (BF)
Image plane ∞

[Various data]
Zoom ratio 3.76
Wide Angle Medium Telephoto Focal Length 103.00 200.08 387.40
F number 5.15 5.90 6.50
Full angle of view 2ω 23.31 11.93 6.15
Image height Y 21.63 21.63 21.63
Total lens length 212.15 255.54 289.15

[Variable interval data]
wide-angle medium-telephoto
d5 3.3680 46.7644 80.3695
d10 5.5000 10.4000 10.4400
d15 27.0319 15.3115 3.5000
d20 18.4761 8.1967 2.1579
d30 9.4339 17.9858 35.4047
d32 18.4981 14.9456 3.5000
d37 16.1889 28.2895 40.1247
BF 33.1482 33.1482 33.1482

[Lens group data]
Group Starting surface Focal length
G1 1 197.57
G2 6 -433.83
G3 11 -40.20
G4 16 79.54
G5 21 193.71
G6 31 74.24
G7 33 -98.68
G8 38 -122.70

FIG. 11 is a lens configuration diagram of an imaging optical system according to Example 2 of the present invention.
A first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with negative refractive power, a fourth lens group G4 with positive refractive power, and a third lens group G4 with positive refractive power. It consists of five lens groups G5, a positive refractive power sixth lens group G6, a negative refractive power seventh lens group G7, and a negative refractive power eighth lens group G8.

When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, the second lens group G2 is fixed with respect to the image plane, and the third lens group G3 moves toward the image plane side. The fourth lens group G4 moves toward the object side, the fifth lens group G5 moves toward the object side, the sixth lens group G6 moves toward the object side from the wide-angle end to the intermediate focal length, and moves toward the object side from the intermediate focal length to the telephoto end. The seventh lens group G7 moves to the object side, and the eighth lens group G8 is fixed with respect to the image plane. An aperture diaphragm S is provided on the image side of the fifth lens group G5, and moves integrally with the fifth lens group G5 during zooming. When focusing from an infinite distance object to a short distance object, the sixth lens group G6 moves along the optical axis toward the object side.

In this embodiment, the front lens group GF consists of the second lens group G2 and the third lens group G3, the first intermediate lens group GM1 consists of the fourth lens group G4 and the fifth lens group G5, and the second intermediate lens group. GM2 is composed of a sixth lens group G6, and the rear lens group GR is composed of a seventh lens group G7 and an eighth lens group G8.

The first lens group G1 is composed of a cemented lens composed of a negative meniscus lens L1 having a convex surface facing the object side and a biconvex lens L2, and a biconvex lens L3.

The second lens group G2 is composed of a positive meniscus lens L4 having a convex surface facing the object side and a negative meniscus lens L5 having a convex surface facing the object side.

The third lens group G3 is composed of a negative meniscus lens L6 having a convex surface facing the object side, and a cemented lens composed of a biconcave lens L7 and a positive meniscus lens L8 having a convex surface facing the object side. Image stabilization is performed by displacing the third lens group G3 in the direction perpendicular to the optical axis.

The fourth lens group G4 is composed of a biconvex lens L9 and a cemented lens composed of a biconvex lens L10 and a negative meniscus lens L11 having a concave surface facing the object side.

The fifth lens group G5 includes a cemented lens composed of a positive meniscus lens L12 having a convex surface facing the object side, a negative meniscus lens L13 having a convex surface facing the object side, and a positive meniscus lens L14 having a convex surface facing the object side. It is composed of a negative meniscus lens L15 with a convex surface on the side and a biconvex lens L16.

The sixth lens group G6 is composed of a cemented lens composed of a biconvex lens L17 and a negative meniscus lens L18 having a concave surface facing the object side.
The seventh lens group G7 is composed of a negative meniscus lens L19 having a convex surface facing the object side, and a cemented lens composed of a biconcave lens L20 and a biconvex lens L21.
The eighth lens group G8 is composed of a negative meniscus lens L22 having a concave surface facing the object side.

Next, the specification values of the variable-magnification imaging optical system provided with the image stabilization function according to Example 2 are shown below.
Numerical example 2
Unit: mm
[Surface data]
Face number rd nd vd
1 266.3440 2.0000 1.80420 46.50
2 99.5861 7.1349 1.49700 81.61
3 -999.9882 0.1500
4 102.3826 6.7102 1.43700 95.10
5-1000.0000 (d5)
6 67.3716 3.8879 1.72047 34.71
7 430.0704 8.9942
8 899.4378 0.9000 1.95375 32.32
9 66.4820 (d9)
10 999.9178 0.9000 1.77250 49.62
11 60.5980 2.7073
12 -53.2762 0.9000 1.72916 54.67
13 61.0918 2.4330 1.84666 23.78
14 1416.9365 (d14)
15 231.4977 2.2997 1.72916 54.67
16 -118.4467 0.1500
17 66.4245 4.8620 1.58144 40.89
18 -48.2582 0.9000 2.05090 26.94
19-211.1957 (d19)
20 31.4430 3.2216 1.69895 30.05
21 89.5680 0.4685
22 52.4231 0.9000 1.90043 37.37
23 23.0153 3.2170 1.59410 60.47
24 47.6296 1.3762
25 65.7306 0.9000 2.00100 29.13
26 34.8049 2.0480
27 513.1218 2.5178 1.59282 68.63
28 -66.6149 2.4410
29 (Aperture) ∞ (d29)
30 48.2821 3.3699 1.59349 67.00
31 -104.6775 0.9000 1.63930 44.87
32 -2113.4127 (d32)
33 166.2366 0.9000 2.00100 29.13
34 38.3213 3.7290
35 -67.2313 0.9000 1.55032 75.50
36 38.9823 5.4250 1.78880 28.43
37 -67.4252 (d37)
38 -40.3031 1.0000 2.05090 26.94
39 -58.8448 (BF)
Image plane ∞

[Various data]
Zoom ratio 3.82
Wide Angle Medium Telephoto Focal Length 101.50 199.84 387.45
F number 5.14 5.93 6.49
Full angle of view 2ω 23.67 11.96 6.15
Image height Y 21.63 21.63 21.63
Total lens length 210.27 255.13 288.50

[Variable interval data]
wide-angle medium-telephoto
d5 4.1084 48.9611 82.3388
d9 5.6631 10.5631 10.6631
d14 27.2499 15.5479 3.5000
d19 18.6314 7.4574 2.1314
d29 9.9143 19.0214 38.1124
d32 19.9581 15.6942 3.0000
d37 13.3810 26.5136 37.3902
BF 33.1238 33.1238 33.1238

[Lens group data]
Group Starting surface Focal length
G1 1 195.26
G2 6 -362.76
G3 10 -40.44
G4 15 74.06
G5 20 215.46
G6 30 82.25
G7 33 -115.99
G8 38 -125.17

FIG. 21 is a lens configuration diagram of an imaging optical system according to Example 3 of the present invention.
A first lens group G1 with positive refractive power, a second lens group G2 with positive refractive power, a third lens group G3 with negative refractive power, a fourth lens group G4 with positive refractive power, and a third lens group G4 with positive refractive power. It consists of five lens groups G5, a positive refractive power sixth lens group G6, a negative refractive power seventh lens group G7, and a negative refractive power eighth lens group G8.

When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, the second lens group G2 is fixed with respect to the image plane, and the third lens group G3 moves from the wide-angle end to the intermediate focal length. The fourth lens group G4 moves toward the object side, the fifth lens group G5 moves toward the object side, and the sixth lens group G6 moves toward the object side. The seventh lens group G7 moves toward the object side, and the eighth lens group G8 is fixed with respect to the image plane. An aperture diaphragm S is provided on the image side of the fifth lens group G5, and moves integrally with the fifth lens group G5 during zooming. When focusing from an infinite distance object to a short distance object, the sixth lens group G6 moves along the optical axis toward the object side.

In this embodiment, the front lens group GF consists of the second lens group G2 and the third lens group G3, the first intermediate lens group GM1 consists of the fourth lens group G4 and the fifth lens group G5, and the second intermediate lens group. GM2 is composed of a sixth lens group G6, and the rear lens group GR is composed of a seventh lens group G7 and an eighth lens group G8.

The first lens group G1 is composed of a cemented lens composed of a negative meniscus lens L1 having a convex surface facing the object side and a biconvex lens L2, and a biconvex lens L3.

The second lens group G2 is composed of a positive meniscus lens L4 having a convex surface facing the object side.

The third lens group G3 is composed of a cemented lens consisting of a biconvex lens L5 and a biconcave lens L6, a cemented lens consisting of a biconcave lens L7, a biconcave lens L8 and a positive meniscus lens L9 having a convex surface facing the object side. In the third lens group, the three lenses L7 to L9 are integrally displaced in the direction perpendicular to the optical axis to perform image stabilization.

The fourth lens group G4 is composed of a biconvex lens L10, a cemented lens composed of a biconvex lens L11 and a negative meniscus lens L12 having a concave surface facing the object side.

The fifth lens group G5 includes a cemented lens composed of a positive meniscus lens L13 having a convex surface facing the object side, a negative meniscus lens L14 having a convex surface facing the object side, and a positive meniscus lens L15 having a convex surface facing the object side. It is composed of a negative meniscus lens L16 with a convex surface facing the side and a positive meniscus lens L17 with a concave surface facing the object side.

The sixth lens group G6 is composed of a positive meniscus lens L18 having a convex surface facing the object side.

The seventh lens group G7 is composed of a biconcave lens L19 and a cemented lens composed of a biconcave lens L20 and a biconvex lens L21.

The eighth lens group G8 is composed of a negative meniscus lens L22 having a concave surface facing the object side.

Next, the specification values of the variable-magnification imaging optical system having the image stabilization function according to the third embodiment are shown below.
Numerical example 3
Unit: mm
[Surface data]
Face number rd nd vd
1 257.2220 2.0000 1.81600 46.62
2 102.1991 7.3359 1.49700 81.61
3 -741.3587 0.1500
4 96.6943 6.6306 1.43700 95.10
5-4465.0993 (d5)
6 99.1585 4.3070 1.72047 34.71
7 4117.9680 (d7)
8 678.0135 2.7629 1.56732 42.84
9 -95.3329 0.9000 1.91082 35.25
10 91.3043 5.0503
11 -702.3996 0.9000 1.77250 49.62
12 69.3864 2.4422
13 -56.5935 0.9000 1.72916 54.67
14 61.3158 2.6016 1.84666 23.78
15 2496.5955 (d15)
16 347.6988 2.3321 1.67790 55.34
17 -98.9801 0.1500
18 71.8417 4.9128 1.58144 40.89
19 -43.9009 0.9000 2.05090 26.94
20 -143.5185 (d20)
21 29.4997 3.2092 1.69895 30.05
22 67.9297 1.1127
23 37.5847 0.9000 1.90043 37.37
24 20.1571 3.2543 1.58913 61.14
25 35.5003 1.6873
26 57.7678 0.9000 2.00100 29.13
27 32.1468 4.3702
28 -239.0346 2.4761 1.61800 63.33
29 -47.0076 2.0844
30 (Aperture) ∞ (d30)
31 38.3238 2.6603 1.55032 75.50
32 248.1691 (d32)
33 -1737.7533 0.9000 2.00100 29.13
34 48.6813 9.1743
35 -43.0253 0.9000 1.55032 75.50
36 106.0121 4.9918 1.78880 28.43
37 -39.8664 (d37)
38 -41.7715 1.0000 2.05090 26.94
39 -59.5306 (BF)
Image plane ∞

[Various data]
Zoom ratio 3.87
Wide Angle Medium Telephoto Focal Length 100.10 199.36 387.30
F number 5.15 5.97 6.50
Full angle of view 2ω 24.10 12.04 6.20
Image height Y 21.63 21.63 21.63
Total lens length 210.15 254.88 290.15

[Variable interval data]
wide-angle medium-telephoto
d5 2.0000 46.7360 82.0003
d7 9.5677 10.5598 9.5161
d15 26.1784 14.9702 3.5000
d20 18.0719 7.8314 2.0005
d30 6.4795 15.7261 31.1427
d32 21.9075 15.9659 3.0000
d37 7.2992 24.4508 40.3445
BF 34.7482 34.7482 34.7482

[Lens group data]
Group Starting surface Focal length
G1 1 187.74
G26 140.96
G3 8 -25.88
G4 16 73.33
G5 21 189.12
G6 31 81.99
G7 33 -128.58
G8 38 -137.20

FIG. 31 is a lens configuration diagram of an imaging optical system according to Example 4 of the present invention.
A first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with positive refractive power, a fourth lens group G4 with positive refractive power, and a third lens group G4 with positive refractive power. It consists of five lens groups G5, a sixth lens group G6 with negative refractive power, and a seventh lens group G7 with negative refractive power.

When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, the second lens group G2 is fixed with respect to the image plane, the third lens group G3 moves toward the object side, and the third lens group G3 moves toward the object side. The fourth lens group G4 moves to the object side, the fifth lens group G5 moves to the object side from the wide-angle end to the intermediate focal length, and moves to the image plane side from the intermediate focal length to the telephoto end, and the sixth lens group G6 moves to the object side. It moves to the object side, and the seventh lens group G7 is fixed with respect to the image plane. An aperture diaphragm S is provided on the image side of the fourth lens group G4, and moves integrally with the fourth lens group G4 during zooming. When focusing from an infinite distance object to a short distance object, the fifth lens group G5 moves along the optical axis toward the object side.

In this embodiment, the front lens group GF consists of the second lens group G2, the first intermediate lens group GM1 consists of the third lens group G3 and the fourth lens group G4, and the second intermediate lens group GM2 consists of the fifth lens group. G5, and the rear lens group GR is composed of a sixth lens group G6 and a seventh lens group G7.

The first lens group G1 is composed of a cemented lens composed of a negative meniscus lens L1 having a convex surface facing the object side and a biconvex lens L2, and a biconvex lens L3.

The second lens group G2 includes a positive meniscus lens L4 having a convex surface facing the object side, a cemented lens composed of a biconvex lens L5 and a biconcave lens L6, a negative meniscus lens L7 having a convex surface facing the object side, and a biconcave lens L8. It is composed of a cemented lens composed of a biconvex lens L9. In the second lens group, the three lenses L7 to L9 are integrally displaced in the direction perpendicular to the optical axis to perform image stabilization.

The third lens group G3 is composed of a biconvex lens L10 and a cemented lens composed of a biconvex lens L11 and a negative meniscus lens L12 having a concave surface facing the object side.

The fourth lens group G4 includes a cemented lens composed of a positive meniscus lens L13 having a convex surface facing the object side, a negative meniscus lens L14 having a convex surface facing the object side, and a positive meniscus lens L15 having a convex surface facing the object side. It is composed of a negative meniscus lens L16 with a convex surface facing the side and a positive meniscus lens L17 with a concave surface facing the object side.

The fifth lens group G5 is composed of a positive meniscus lens L18 having a convex surface facing the object side.

The sixth lens group G6 is composed of a biconcave lens L19 and a cemented lens composed of a biconcave lens L20 and a biconvex lens L21.

The seventh lens group G7 is composed of a negative meniscus lens L22 having a concave surface facing the object side.

Next, the specification values of the variable-magnification imaging optical system having a vibration reduction function according to Example 4 are shown below.
Numerical example 4
Unit: mm
[Surface data]
Face number rd nd vd
1 297.5437 2.0000 1.80420 46.50
2 106.2425 7.2662 1.49700 81.61
3 -564.7647 0.1500
4 99.0415 7.4346 1.43700 95.10
5-3173.2833 (d5)
6 83.2177 3.1401 1.72047 34.71
7 572.4728 7.9089
8 200.8571 2.2364 1.56732 42.84
9 -181.1771 0.9000 1.91082 35.25
10 79.3047 6.0243
11 1144.2839 0.9000 1.77250 49.62
12 56.2468 3.0354
13 -48.0194 0.9000 1.72916 54.67
14 67.9918 3.4043 1.84666 23.78
15 -444.6079 (d15)
16 433.8369 2.5491 1.69680 55.46
17 -82.9224 0.1500
18 73.0108 4.9692 1.58144 40.89
19 -46.7398 0.9000 2.05090 26.94
20 -276.3498 (d20)
21 30.4272 3.3770 1.69895 30.05
22 79.0345 0.1632
23 40.8026 0.9000 1.90043 37.37
24 20.3844 3.6931 1.59410 60.47
25 39.8972 1.6135
26 61.3112 0.9000 2.00100 29.13
27 33.8750 2.5099
28 -288.7244 2.5628 1.61997 63.88
29 -50.1308 2.0806
30 (Aperture) ∞ (d30)
31 39.0560 2.8987 1.55032 75.50
32 406.2481 (d32)
33 -427.0730 0.9000 2.00100 29.13
34 45.5801 3.0224
35 -45.1709 0.9000 1.55032 75.50
36 62.7138 6.0000 1.78880 28.43
37 -37.4867 (d37)
38 -38.1895 1.0000 2.05090 26.94
39 -61.9328 (BF)
Image plane ∞

[Various data]
Zoom ratio 3.76
Wide Angle Medium Telephoto Focal Length 103.00 199.42 387.30
F number 5.15 5.86 6.49
Full angle of view 2ω 23.26 11.97 6.15
Image height Y 21.63 21.63 21.63
Total lens length 215.15 262.27 293.15

[Variable interval data]
wide-angle medium-telephoto
d5 5.3730 52.4910 83.3732
d15 26.8424 17.2873 3.5000
d20 19.7478 8.8354 5.5985
d30 6.4259 21.7592 39.8843
d32 20.0237 13.1613 3.0000
d37 15.9410 27.9373 36.9980
BF 34.4048 34.4048 34.4048

[Lens group data]
Group Starting surface Focal length
G1 1 191.05
G2 6 -39.80
G3 16 83.04
G4 21 165.33
G5 31 78.30
G6 33 -127.62
G7 38 -96.88

FIG. 41 is a lens configuration diagram of an imaging optical system according to Example 5 of the present invention.
A first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with negative refractive power, a fourth lens group G4 with positive refractive power, and a third lens group G4 with positive refractive power. It consists of five lens groups G5, a positive refractive power sixth lens group G6, a negative refractive power seventh lens group G7, and a negative refractive power eighth lens group G8.

When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, the second lens group G2 is fixed with respect to the image plane, and the third lens group G3 moves toward the image plane side. The fourth lens group G4 moves toward the object side, the fifth lens group G5 moves toward the object side, the sixth lens group G6 moves toward the object side from the wide-angle end to the intermediate focal length, and moves toward the object side from the intermediate focal length to the telephoto end. The seventh lens group G7 moves to the object side, and the eighth lens group G8 is fixed with respect to the image plane. An aperture diaphragm S is provided on the image side of the fifth lens group G5, and moves integrally with the fifth lens group G5 during zooming. When focusing from an infinite distance object to a short distance object, the sixth lens group G6 moves along the optical axis toward the object side.

In this embodiment, the front lens group GF consists of the second lens group G2 and the third lens group G3, the first intermediate lens group GM1 consists of the fourth lens group G4 and the fifth lens group G5, and the second intermediate lens group. GM2 is composed of a sixth lens group G6, and the rear lens group GR is composed of a seventh lens group G7 and an eighth lens group G8.

The first lens group G1 is composed of a cemented lens composed of a negative meniscus lens L1 having a convex surface facing the object side and a biconvex lens L2, and a biconvex lens L3.

The second lens group G2 is composed of a positive meniscus lens L4 having a convex surface facing the object side, and a cemented lens composed of a biconvex lens L5 and a biconcave lens L6.

The third lens group G3 is composed of a negative meniscus lens L7 having a convex surface facing the object side, and a cemented lens composed of a biconcave lens L8 and a biconvex lens L9. Image stabilization is performed by displacing the third lens group G3 in the direction perpendicular to the optical axis.

The fourth lens group G4 is composed of a biconvex lens L10, a cemented lens composed of a biconvex lens L11 and a negative meniscus lens L12 having a concave surface facing the object side.

The fifth lens group G5 includes a cemented lens composed of a positive meniscus lens L13 having a convex surface facing the object side, a negative meniscus lens L14 having a convex surface facing the object side, and a positive meniscus lens L15 having a convex surface facing the object side. It is composed of a negative meniscus lens L16 with a convex surface on the side and a biconvex lens L17.

The sixth lens group G6 is composed of a biconvex lens L18.

The seventh lens group G7 is composed of a negative meniscus lens L19 having a convex surface facing the object side, and a cemented lens composed of a biconcave lens L20 and a biconvex lens L21.

The eighth lens group G8 is composed of a negative meniscus lens L22 having a concave surface facing the object side.

Next, the specification values of the variable-magnification imaging optical system having a vibration reduction function according to Example 5 are shown below.
Numerical example 5
Unit: mm
[Surface data]
Face number rd nd vd
1 259.8769 2.0000 1.80420 46.50
2 101.6883 8.5000 1.49700 81.61
3 -999.9998 0.1500
4 105.1493 8.0000 1.43700 95.10
5-1000.0000 (d5)
6 73.7159 4.5000 1.72047 34.71
7 241.0898 9.7379
8 116.1545 2.3751 1.56732 42.84
9 -560.5922 0.9000 1.91082 35.25
10 58.0640 (d10)
11 1000.0000 0.9000 1.77250 49.62
12 59.9450 2.8793
13 -47.3114 0.9000 1.72916 54.67
14 79.6697 2.8644 1.84666 23.78
15 -310.7201 (d15)
16 267.1568 2.5091 1.69680 55.46
17 -91.7527 0.1500
18 69.6950 4.7658 1.58144 40.89
19 -48.5659 0.9000 2.05090 26.94
20 -283.1789 (d20)
21 29.6954 3.3104 1.69895 30.05
22 79.8061 0.4507
23 48.1095 0.9000 1.90043 37.37
24 21.2929 3.4004 1.59410 60.47
25 43.3138 1.4622
26 63.4110 0.9000 2.00100 29.13
27 33.9518 2.1073
28 995.9835 2.5121 1.61997 63.88
29 -62.1193 2.3967
30 (Aperture) ∞ (d30)
31 41.3817 2.9658 1.55032 75.50
32-984.8407 (d32)
33 306.7629 0.9000 2.00100 29.13
34 37.1644 3.2166
35 -47.7101 0.9000 1.55032 75.50
36 44.9366 5.9970 1.78880 28.43
37 -44.8010 (d37)
38 -38.4224 1.0000 2.05090 26.94
39 -63.1658 (BF)
Image plane ∞

[Various data]
Zoom ratio 3.76
Wide Angle Medium Telephoto Focal Length 103.00 199.32 387.38
F number 5.14 5.92 6.50
Full angle of view 2ω 23.20 11.93 6.12
Image height Y 21.63 21.63 21.63
Total lens length 212.55 255.08 288.60

[Variable interval data]
wide-angle medium-telephoto
d5 2.1451 44.6743 78.1987
d10 5.0001 9.9001 9.9116
d15 27.3973 15.1417 3.5000
d20 20.9211 9.9352 3.8994
d30 6.8285 17.2918 36.6088
d32 19.1116 15.2714 3.0001
d37 13.8424 25.5605 36.1811
BF 32.8498 32.8498 32.8499

[Lens group data]
Group Starting surface Focal length
G1 1 194.47
G2 6 -318.41
G3 11 -42.49
G4 16 77.74
G5 21 203.38
G6 31 72.24
G7 33 -109.39
G8 38-95.31

FIG. 51 is a lens configuration diagram of an imaging optical system according to Example 6 of the present invention.
A first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with negative refractive power, a fourth lens group G4 with positive refractive power, and a third lens group G4 with positive refractive power. It consists of five lens groups G5, a positive refractive power sixth lens group G6, a negative refractive power seventh lens group G7, and a negative refractive power eighth lens group G8.

When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, the second lens group G2 is fixed with respect to the image plane, and the third lens group G3 moves toward the image plane side. The fourth lens group G4 moves toward the object side, the fifth lens group G5 moves toward the object side, the sixth lens group G6 moves toward the object side from the wide-angle end to the intermediate focal length, and moves toward the object side from the intermediate focal length to the telephoto end. The seventh lens group G7 moves to the object side, and the eighth lens group G8 is fixed with respect to the image plane. An aperture diaphragm S is provided on the image side of the fifth lens group G5, and moves integrally with the fifth lens group G5 during zooming. When focusing from an infinite distance object to a short distance object, the sixth lens group G6 moves along the optical axis toward the object side.

In this embodiment, the front lens group GF consists of the second lens group G2 and the third lens group G3, the first intermediate lens group GM1 consists of the fourth lens group G4 and the fifth lens group G5, and the second intermediate lens group. GM2 is composed of a sixth lens group G6, and the rear lens group GR is composed of a seventh lens group G7 and an eighth lens group G8.

The first lens group G1 is composed of a cemented lens composed of a negative meniscus lens L1 having a convex surface facing the object side and a biconvex lens L2, and a biconvex lens L3.

The second lens group G2 is composed of a positive meniscus lens L4 having a convex surface facing the object side, and a cemented lens composed of a biconvex lens L5 and a biconcave lens L6.

The third lens group G3 is composed of a negative meniscus lens L7 having a convex surface facing the object side, and a cemented lens composed of a biconcave lens L8 and a positive meniscus lens L9 having a convex surface facing the object side. Image stabilization is performed by displacing the third lens group G3 in the direction perpendicular to the optical axis.

The fourth lens group G4 is composed of a biconvex lens L10, a cemented lens composed of a biconvex lens L11 and a negative meniscus lens L12 having a concave surface facing the object side.

The fifth lens group G5 includes a cemented lens composed of a positive meniscus lens L13 having a convex surface facing the object side, a negative meniscus lens L14 having a convex surface facing the object side, and a positive meniscus lens L15 having a convex surface facing the object side. It is composed of a negative meniscus lens L16 with a convex surface on the side and a biconvex lens L17.

The sixth lens group G6 is composed of a biconvex lens L18.

The seventh lens group G7 is composed of a negative meniscus lens L19 having a convex surface facing the object side, and a cemented lens composed of a biconcave lens L20 and a biconvex lens L21.

The eighth lens group G8 is composed of a negative meniscus lens L22 having a concave surface facing the object side.

Next, the specification values of the variable-magnification imaging optical system having a vibration reduction function according to Example 6 are shown below.
Numerical Example 6
Unit: mm
[Surface data]
Face number rd nd vd
1 260.8067 2.0000 1.81600 46.62
2 103.6022 7.0427 1.49700 81.61
3 -1034.0909 0.1500
4 103.2948 7.3695 1.43700 95.10
5-1526.2710 (d5)
6 81.6911 4.1781 1.72047 34.71
7 770.4240 7.2424
8 119.4017 2.6688 1.56732 42.84
9 -174.0954 0.9000 1.90525 35.04
10 62.3771 (d10)
11 4348.5697 0.9000 1.72916 54.67
12 65.0312 2.6208
13 -49.1044 0.9000 1.72916 54.67
14 63.3276 2.5427 1.84666 23.78
15 1618.2166 (d15)
16 243.1103 2.4743 1.65160 58.55
17 -93.8608 0.1500
18 73.2594 4.7115 1.58144 40.89
19 -45.8279 0.9000 2.05090 26.94
20 -195.5247 (d20)
21 31.0411 3.7226 1.71736 29.50
22 127.9717 1.2333
23 107.3155 0.9000 1.90043 37.37
24 27.1309 2.9515 1.58913 61.14
25 61.6032 1.2264
26 71.3491 0.9000 2.00100 29.13
27 35.2559 1.8465
28 173.8071 2.9307 1.59282 68.63
29 -62.0397 2.3472
30 (Aperture) ∞ (d30)
31 49.0564 2.8500 1.55032 75.50
32 -738.1435 (d32)
33 93.0420 0.9000 2.00100 29.13
34 35.6303 5.0748
35 -67.8525 0.9000 1.55032 75.50
36 37.1131 6.0000 1.78880 28.43
37 -83.1843 (d37)
38 -37.5856 1.0000 2.05090 26.94
39 -63.2608 (BF)
Image plane ∞

[Various data]
Zoom ratio 3.76
Wide Angle Medium Telephoto Focal Length 102.89 199.98 387.20
F number 5.12 5.91 6.49
Full angle of view 2ω 23.28 11.91 6.14
Image height Y 21.63 21.63 21.63
Total lens length 212.15 255.61 289.06

[Variable interval data]
wide-angle medium-telephoto
d5 7.0023 50.4683 83.9176
d10 5.5000 10.3500 10.4400
d15 26.3122 15.2446 3.5000
d20 19.1753 7.6664 2.2972
d30 9.5481 19.3386 37.6901
d32 22.4070 17.0000 4.0000
d37 9.5530 22.8959 34.5681
BF 31.1164 31.1164 31.1164

[Lens group data]
Group Starting surface Focal length
G1 1 198.74
G26-406.32
G3 11 -40.08
G4 16 77.64
G5 21 176.58
G6 31 83.69
G7 33 -126.31
G8 38 -89.92

FIG. 61 is a lens configuration diagram of an imaging optical system according to Example 7 of the present invention.
A first lens group G1 with positive refractive power, a second lens group G2 with negative refractive power, a third lens group G3 with negative refractive power, a fourth lens group G4 with positive refractive power, and a third lens group G4 with positive refractive power. It consists of five lens groups G5, a positive refractive power sixth lens group G6, a negative refractive power seventh lens group G7, and a negative refractive power eighth lens group G8.

When zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, the second lens group G2 is fixed with respect to the image plane, and the third lens group G3 moves toward the image plane side. The fourth lens group G4 moves toward the object side, the fifth lens group G5 moves toward the object side, the sixth lens group G6 moves toward the object side, the seventh lens group G7 moves toward the object side, and the eighth lens group G7 moves toward the object side. The lens group G8 is fixed with respect to the image plane. An aperture diaphragm S is provided on the image side of the fifth lens group G5, and moves integrally with the fifth lens group G5 during zooming. When focusing from an infinite distance object to a short distance object, the sixth lens group G6 moves along the optical axis toward the object side.

In this embodiment, the front lens group GF consists of the second lens group G2 and the third lens group G3, the first intermediate lens group GM1 consists of the fourth lens group G4 and the fifth lens group G5, and the second intermediate lens group. GM2 is composed of a sixth lens group G6, and the rear lens group GR is composed of a seventh lens group G7 and an eighth lens group G8.

The first lens group G1 is composed of a cemented lens composed of a negative meniscus lens L1 having a convex surface facing the object side and a biconvex lens L2, and a biconvex lens L3.

The second lens group G2 is composed of a positive meniscus lens L4 having a convex surface facing the object side and a negative meniscus lens L5 having a convex surface facing the object side.

The third lens group G3 is composed of a negative meniscus lens L6 having a convex surface facing the object side, and a cemented lens composed of a biconcave lens L7 and a positive meniscus lens L8 having a convex surface facing the object side. Image stabilization is performed by displacing the third lens group G3 in the direction perpendicular to the optical axis.

The fourth lens group G4 is composed of a biconvex lens L9 and a cemented lens composed of a biconvex lens L10 and a negative meniscus lens L11 having a concave surface facing the object side.

The fifth lens group G5 includes a cemented lens composed of a positive meniscus lens L12 having a convex surface facing the object side, a negative meniscus lens L13 having a convex surface facing the object side, and a positive meniscus lens L14 having a convex surface facing the object side. It is composed of a negative meniscus lens L15 with a convex surface on the side and a biconvex lens L16.

The sixth lens group G6 is composed of a cemented lens composed of a biconvex lens L17 and a negative meniscus lens L18 having a concave surface facing the object side.

The seventh lens group G7 is composed of a negative meniscus lens L19 having a convex surface facing the object side, and a cemented lens composed of a biconcave lens L20 and a biconvex lens L21.

The eighth lens group G8 is composed of a negative meniscus lens L22 having a concave surface facing the object side.

Next, the specification values of the variable-magnification imaging optical system having a vibration reduction function according to Example 7 are shown below.
Numerical example 7
Unit: mm
[Surface data]
Face number rd nd vd
1 269.9623 2.0000 1.80420 46.50
2 98.6558 7.2641 1.49700 81.61
3 -1000.0000 0.1500
4 102.0743 6.8059 1.43700 95.10
5-1000.0000 (d5)
6 69.4121 3.8877 1.72047 34.71
7 429.0748 8.9520
8 659.2138 0.9000 1.95375 32.32
9 69.1195 (d9)
10 1000.0000 0.9000 1.77250 49.62
11 58.5334 2.7742
12 -51.9627 0.9000 1.72916 54.67
13 60.8148 2.4752 1.84666 23.78
14 2926.5512 (d14)
15 320.7635 2.3625 1.72916 54.67
16 -100.1529 0.1500
17 69.5963 4.8422 1.58144 40.89
18 -47.2299 0.9000 2.05090 26.94
19 -216.2545 (d19)
20 32.3811 3.1152 1.69895 30.05
21 88.1160 0.5529
22 55.6435 0.9000 1.90043 37.37
23 24.9408 3.1002 1.59410 60.47
24 53.1162 1.2673
25 67.1912 0.9000 2.00100 29.13
26 35.4891 2.2584
27 981.4323 2.5974 1.59410 60.47
28 -61.4217 2.3335
29 (Aperture) ∞ (d29)
30 45.7903 3.6022 1.59282 68.63
31 -79.3039 0.9000 1.66672 48.32
32 -676.7993 (d32)
33 244.9433 0.9000 2.00100 29.13
34 39.8626 4.7327
35 -61.0700 0.9000 1.55032 75.50
36 42.1273 5.3895 1.78880 28.43
37 -63.6196 (d37)
38 -40.1794 1.0000 2.05090 26.94
39 -58.6795 (BF)
Image plane ∞

[Various data]
Zoom ratio 3.78
Wide Angle Medium Telephoto Focal Length 102.53 199.83 387.40
F number 5.14 5.93 6.48
Full angle of view 2ω 23.47 11.98 6.17
Image height Y 21.63 21.63 21.63
Total lens length 212.15 256.25 290.65

[Variable interval data]
wide-angle medium-telephoto
d5 4.6712 48.7706 83.1714
d9 6.1761 10.9125 11.1761
d14 25.0048 14.1473 3.5000
d19 22.4695 10.6441 2.4791
d29 6.9639 14.9927 31.9593
d32 19.7439 15.4983 3.0000
d37 14.3375 28.5005 42.5808
BF 33.0682 33.0682 33.0682

[Lens group data]
Group Starting surface Focal length
G1 1 197.37
G2 6 -436.30
G3 10 -39.65
G4 15 76.63
G5 20 187.10
G6 30 76.97
G7 33 -101.96
G8 38 -124.73

Values corresponding to conditional expressions corresponding to the above examples are shown below.
[Value corresponding to conditional expression]
Conditional expression/Example 1 2 3 4
(1) 1.2＜LT1m2t/f1m2t＜1.55 1.46 1.38 1.42 1.48
(2) -0.70＜fRw/fw＜-0.30 -0.47 -0.53 -0.57 -0.45
(3) 0.20＜EXPt/LTt＜0.40 0.30 0.31 0.33 0.30
(4) 0.70<|LTFpnt/fFpnt|<0.95 0.84 0.85 0.82 0.88

Conditional expression/Example 5 6 7
(1) 1.20<LT1m2t/f1m2t<1.55 1.49 1.41 1.48
(2) -0.70＜fRw/fw＜-0.30 -0.42 -0.45 -0.48
(3) 0.20＜EXPt/LTt＜0.40 0.29 0.27 0.30
(4) 0.70<|LTFpnt/fFpnt|<0.95 0.83 0.86 0.86

G1 1st lens group G2 2nd lens group G3 3rd lens group G4 4th lens group G5 5th lens group G6 6th lens group G7 7th lens group G8 8th lens group GF Front side lens group GM1 Middle 1 lens group GM2 Intermediate 2 lens group GR Rear lens group S Aperture diaphragm I Image sensor

Claims (4)

In order from the object side, a first lens group G1 having positive refractive power, a front lens group GF having negative refractive power as a whole, an intermediate lens group GM1 having positive refractive power as a whole, and an intermediate lens group having positive refractive power. Consists of two lens groups GM2 and a rear lens group GR having a negative refractive power as a whole,
The front lens group GF is composed of one or two lens groups, and includes a vibration reduction lens group with a negative refractive power that corrects image blur by moving in a direction perpendicular to the optical axis,
The first intermediate lens group GM1 is composed of two lens groups with positive refractive power, and has an aperture stop S closest to the image side,
The intermediate two lens group GM2 is one lens group with positive refractive power, and is composed of two or less lenses,
The rear lens group GR is composed of two lens groups with negative refractive power,
During zooming from the wide-angle end to the telephoto end, the first lens group G1 moves toward the object side, the distance between the first lens group G1 and the front lens group GF increases, and the distance between the front lens group GF and the intermediate lens group increases. The distance between the first lens group GM1 decreases, the distance between the first intermediate lens group GM1 and the second intermediate lens group GM2 changes, the distance between the second intermediate lens group GM2 and the rear lens group GR decreases, and further, When the front lens group GF is composed of two lens groups, the distance between the two lens groups in the front lens group GF changes, and the distance between the two lens groups in the middle lens group GM1 changes, the distance between the two lens groups in the rear lens group GR varies,
When focusing from infinity to a short distance, the second intermediate lens group GM2 moves along the optical axis toward the object side,
A variable-magnification imaging optical system having a vibration reduction function, characterized by satisfying the following conditional expression.
(1) 1.20<LT1m2t/f1m2t<1.55
(2) -0.7<fRw/fw<-0.3
however,
LT1m2t: Length from the most object-side surface to the image-side focal point of the combined system from the first lens group G1 to the intermediate two lens group GM2 at the telephoto end and infinity focus state f1m2t: Telephoto end, infinity Focal length fRw of the composite system from the first lens group G1 to the intermediate two lens group GM2 in the focused state: focal length fw of the rear lens group GR at the wide-angle end: wide-angle end, in the infinity focused state Let it be the focal length of the entire system. In the rear lens group GR, when zooming from the wide-angle end to the telephoto end, the lens group on the object side of the rear lens group GR moves toward the object side, and the group on the image side is fixed with respect to the image plane. 2. A variable-magnification imaging optical system with a vibration reduction function according to claim 1, wherein the following conditional expressions are satisfied: .
(3) 0.20<EXPt/LTt<0.40
however,
EXPt: length from the exit pupil to the image plane at the telephoto end and infinity focus state LTt: length from the most object-side surface of the optical system to the image plane at the telephoto end and infinity focus state. The front lens group GF comprises, in order from the object side, a GFp lens component with a positive refractive power, a GFn lens component with a negative refractive power, and a vibration reduction lens group with a negative refractive power, the GFp lens component and the GFn lens component. are separated by an air gap, and the GFp lens component and the GFn lens component do not include an air gap inside and satisfy the following conditional expression: Variable magnification imaging optical system with anti-vibration function.
(4) 0.70<|LTFpnt/fFpnt|<0.95
however,
LTFpnt: Length from the most object-side surface to the image-side focal point of the composite system of the GFp lens component and the GFn lens component at the telephoto end fFpnt: Length of the composite system of the GFp lens component and the GFn lens component at the telephoto end Let it be the focal length. 4. The anti-vibration function according to any one of claims 1 to 3, wherein at least part of said front lens group GF is fixed with respect to an image plane during zooming from the wide-angle end to the telephoto end. variable magnification imaging optical system.

Images