WO2012081603A1 - Optical system, image pickup device, and method for manufacturing optical system - Google Patents

Abstract

Disclosed is an optical system, which is characterized in that the optical system has a first lens element and a second lens element, which can be shifted such that each lens element includes a component in the direction perpendicular to an optical axis, the second lens element is configured of the first lens element and other lens element, and that image plane correction is performed by shifting the first lens element or the second lens element such that the component in the direction perpendicular to the optical axis is included. Consequently, the optical system having suitable vibration-proofing functions, an image pickup device provided with the optical system, and a method for manufacturing the optical system are provided.

Description

OPTICAL SYSTEM, IMAGING DEVICE, AND OPTICAL SYSTEM MANUFACTURING METHOD

The present invention relates to an optical system having an anti-vibration function, an imaging apparatus including the optical system, and a method for manufacturing the optical system.

Conventionally, an optical system having an image stabilization function and used for an imaging apparatus such as a camera has been proposed (for example, see Patent Document 1).

JP 2001-249276 A

However, the conventional optical system having the image stabilization function has a problem that when the image plane correction amount is increased, the lens shift amount is increased and control becomes difficult.

The present invention has been made in view of such a problem, and an object thereof is to provide an optical system having a suitable anti-vibration function, an imaging device including the optical system, and a method for manufacturing the optical system.

In order to achieve the above object, a first aspect of the present invention includes a first lens element and a second lens element that can be shifted so as to include a component in a direction perpendicular to the optical axis. The lens element includes the first lens element and another lens element, and the first lens element or the second lens element is shifted so as to include a component in a direction perpendicular to the optical axis. Provided is an optical system characterized by performing correction.

Also, the second aspect of the present invention provides an imaging apparatus comprising the optical system according to the first aspect of the present invention.

The third aspect of the present invention includes a first lens element and a second lens element that can be shifted to include a component in a direction perpendicular to the optical axis, respectively, from the wide-angle end state to the telephoto end state. Upon zooming, either the first lens element or the second lens element includes a component in a direction perpendicular to the optical axis in accordance with a change in focal length from the wide-angle end state to the telephoto end state. The optical system is characterized in that image plane correction is performed by shifting in such a manner as to satisfy the following condition.
| FB '| <| fA' |
fw ≦ fh ≦ (| fB ′ | / | fA ′ |) × ft × 1.50
(| FB ′ | / | fA ′ |) × ft × 0.50 ≦ fk ≦ ft
However,
fA ′: focal length of the first lens element fB ′: focal length of the second lens element fw: focal length of the entire optical system in the wide-angle end state ft: focal length of the entire optical system in the telephoto end state fh: Focal length of the entire optical system when image plane correction is performed by the first lens element fk: Focal length of the entire optical system when image plane correction is performed by the second lens element

The fourth aspect of the present invention includes a first lens element, a second lens element, and a third lens element that can be shifted so as to include a component in a direction perpendicular to the optical axis, respectively, from the wide-angle end state. When zooming to the telephoto end state, any one of the first lens element, the second lens element, or the third lens element is changed according to a change in focal length from the wide-angle end state to the telephoto end state. Provided is an optical system characterized in that image plane correction is performed by shifting so as to include a component in a direction perpendicular to the optical axis.

According to a fifth aspect of the present invention, there is provided an image pickup apparatus comprising the optical system according to the third aspect of the present invention.
According to a sixth aspect of the present invention, there is provided an imaging apparatus comprising the optical system according to the fourth aspect of the present invention.

A seventh aspect of the present invention is a method of manufacturing an optical system having a first lens element and a second lens element, wherein the second lens element is composed of the first lens element and another lens element. The first lens element and the second lens element are arranged so as to be shiftable so as to include components in the direction perpendicular to the optical axis, respectively, and the image plane correction is performed by the first lens element or the second lens element. An optical system manufacturing method is provided in which any one of the above is shifted so as to include a component in a direction perpendicular to the optical axis.

A seventh aspect of the present invention is a method of manufacturing an optical system having a first lens element and a second lens element, wherein the second lens element is composed of the first lens element and another lens element. The first lens element and the second lens element are arranged so as to be shiftable so as to include components in the direction perpendicular to the optical axis, respectively, and the image plane correction is performed by the first lens element or the second lens element. An optical system manufacturing method is provided in which any one of the above is shifted so as to include a component in a direction perpendicular to the optical axis.

According to an eighth aspect of the present invention, there is provided a method of manufacturing an optical system having a first lens element and a second lens element, wherein the first lens element and the second lens element are respectively connected to an optical axis. The first lens is configured to be shiftable so as to include a component in the vertical direction, and changes the focal length from the wide-angle end state to the telephoto end state upon zooming from the wide-angle end state to the telephoto end state. An image plane correction is performed by shifting either the element or the second lens element so as to include a component in a direction perpendicular to the optical axis, and satisfying the following condition: An optical system manufacturing method is provided.
| FB '| <| fA' |
fw ≦ fh ≦ (| fB ′ | / | fA ′ |) × ft × 1.50
(| FB ′ | / | fA ′ |) × ft × 0.50 ≦ fk ≦ ft
However,
fA ′: focal length of the first lens element fB ′: focal length of the second lens element fw: focal length of the entire optical system in the wide-angle end state ft: focal length of the entire optical system in the telephoto end state fh: Focal length of the entire optical system when image plane correction is performed by the first lens element fk: Focal length of the entire optical system when image plane correction is performed by the second lens element

According to a ninth aspect of the present invention, there is provided a method of manufacturing an optical system having a first lens element, a second lens element, and a third lens element, the first lens element, the second lens element, and the first lens element. Each of the three lens elements is configured to be shiftable so as to include a component in a direction perpendicular to the optical axis, and the focal point from the wide-angle end state to the telephoto end state upon zooming from the wide-angle end state to the telephoto end state Image plane correction is performed by shifting any one of the first lens element, the second lens element, or the third lens element so as to include a component in a direction perpendicular to the optical axis in accordance with a change in distance. An optical system manufacturing method is provided that is configured to perform the above.

According to the present invention, it is possible to provide an optical system having a suitable anti-vibration function, an imaging apparatus including the optical system, and a method for manufacturing the optical system.

FIG. 1 is a diagram showing a configuration of an optical system according to a first example of the first embodiment of the present invention. 2A, 2B, 2C, and 2D are aberration diagrams in the wide-angle end state of the optical system according to the first example at the time of focusing on infinity, FIG. 2A is a diagram of various aberrations, and FIG. FIG. 2C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B. FIG. 2C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B. FIG. It is a meridional transverse aberration diagram at the time. 3A, 3B, 3C, and 3D are aberration diagrams in the intermediate focal length state at the time of focusing on infinity of the optical system according to the first example, FIG. 3A is various aberration diagrams, and FIG. 3B is a lens element. FIG. 3C is a meridional lateral aberration diagram when image blur correction is performed in A, FIG. 3C is a meridional lateral aberration diagram when image blur correction is performed in the lens element B, and FIG. 3D is image blur correction in the lens element C; It is a meridional lateral aberration diagram when it is performed. 4A, 4B, 4C, and 4D are aberration diagrams in the telephoto end state of the optical system according to the first example when focused on infinity, FIG. 4A is various aberration diagrams, and FIG. FIG. 4C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B, and FIG. 4D is a meridional lateral aberration diagram when image blur correction is performed with the lens element C. It is a meridional transverse aberration diagram at the time. FIG. 5 is a diagram showing a configuration of an optical system according to Example 2 of Embodiment 1 of the present invention. 6A, 6B, 6C, and 6D are aberration diagrams in the wide-angle end state of the optical system according to Example 2 at the time of focusing on infinity, FIG. 6A is various aberration diagrams, and FIG. 6B is a lens element A. FIG. 6C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B, and FIG. 6D is a meridional lateral aberration diagram when image blur correction is performed with the lens element C. It is a meridional transverse aberration diagram at the time. 7A, 7B, 7C, and 7D are aberration diagrams in the intermediate focal length state at the time of focusing on infinity of the optical system according to the second example, FIG. 7A is various aberration diagrams, and FIG. 7B is a lens element. FIG. 7C is a meridional lateral aberration diagram when image blur correction is performed in A, FIG. 7C is a meridional lateral aberration diagram when image blur correction is performed in lens element B, and FIG. It is a meridional lateral aberration diagram when it is performed. 8A, 8B, 8C, and 8D are aberration diagrams in the telephoto end state of the optical system according to Example 2 at the time of focusing on infinity, FIG. 8A is various aberration diagrams, and FIG. 8B is a lens element A. FIG. 8C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B, FIG. 8C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B, and FIG. It is a meridional transverse aberration diagram at the time. FIG. 9 is a diagram showing a configuration of an optical system according to the third example of the first embodiment of the present invention. FIGS. 10A, 10B, 10C, and 10D are aberration diagrams in the wide-angle end state of the optical system according to Example 3 at the time of focusing on infinity, FIG. 10A is various aberration diagrams, and FIG. FIG. 10C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B. FIG. 10C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B. FIG. It is a meridional transverse aberration diagram at the time. 11A, 11B, 11C, and 11D are aberration diagrams in the intermediate focal length state when the optical system according to Example 3 is focused at infinity, FIG. 11A is various aberration diagrams, and FIG. 11B is a lens element. FIG. 11C is a meridional lateral aberration diagram when image blur correction is performed in A, FIG. 11C is a meridional lateral aberration diagram when image blur correction is performed in lens element B, and FIG. It is a meridional lateral aberration diagram when it is performed. 12A, 12B, 12C, and 12D are aberration diagrams in the telephoto end state of the optical system according to the third example when focused on infinity, FIG. 12A is various aberration diagrams, and FIG. 12B is a lens element A. 12C is a meridional lateral aberration diagram when image blur correction is performed in FIG. 12, FIG. 12C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B, and FIG. 12D is image blur correction performed with the lens element C. It is a meridional transverse aberration diagram at the time. FIG. 13 is a diagram showing a configuration of an optical system according to Example 4 of Embodiment 1 of the present invention. 14A, 14B, 14C, and 14D are aberration diagrams in the wide-angle end state of the optical system according to Example 4 at the time of focusing on infinity, FIG. 14A is various aberration diagrams, and FIG. FIG. 14C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B, and FIG. 14D is a meridional lateral aberration diagram when image blur correction is performed with the lens element C. It is a meridional transverse aberration diagram at the time. 15A, 15B, 15C, and 15D are aberration diagrams in the intermediate focal length state when the optical system according to Example 4 is focused at infinity, FIG. 15A is various aberration diagrams, and FIG. 15B is a lens element. FIG. 15C is a meridional lateral aberration diagram when image blur correction is performed in A, FIG. 15C is a meridional lateral aberration diagram when image blur correction is performed in lens element B, and FIG. It is a meridional lateral aberration diagram when it is performed. 16A, 16B, 16C, and 16D are aberration diagrams in the telephoto end state of the optical system according to Example 4 when focused on infinity, FIG. 16A is various aberration diagrams, and FIG. FIG. 16C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B, FIG. 16C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B, and FIG. It is a meridional transverse aberration diagram at the time. FIG. 17 is a diagram showing a configuration of an optical system according to Example 5 of Embodiment 1 of the present invention. 18A, 18B, 18C, and 18D are aberration diagrams in the wide-angle end state of the optical system according to Example 5 at the time of focusing on infinity, FIG. 18A is various aberration diagrams, and FIG. 18B is a lens element A. FIG. 18C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B, FIG. 18C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B, and FIG. It is a meridional transverse aberration diagram at the time. 19A, 19B, 19C, and 19D are aberration diagrams in the intermediate focal length state at the time of focusing on infinity of the optical system according to the fifth example, FIG. 19A is various aberration diagrams, and FIG. 19B is a lens element. FIG. 19C is a meridional lateral aberration diagram when image blur correction is performed at A, FIG. 19C is a meridional lateral aberration diagram when image blur correction is performed at lens element B, and FIG. It is a meridional lateral aberration diagram when it is performed. 20A, 20B, 20C, and 20D are aberration diagrams in the telephoto end state of the optical system according to Example 5 when focused on infinity, FIG. 20A is various aberration diagrams, and FIG. 20B is a lens element A. FIG. 20C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B, and FIG. 20D is a meridional lateral aberration diagram when image blur correction is performed with the lens element C. FIG. It is a meridional transverse aberration diagram at the time. FIG. 21 is a diagram showing a configuration of an optical system according to Example 6 of Embodiment 1 of the present invention. 22A, 22B, 22C, and 22D are aberration diagrams in the wide-angle end state of the optical system according to Example 6 at the time of focusing on infinity, FIG. 22A is various aberration diagrams, and FIG. 22B is a lens element A. FIG. 22C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B, and FIG. 22D is a meridional lateral aberration diagram when image blur correction is performed with the lens element C. It is a meridional transverse aberration diagram at the time. 23A, 23B, 23C, and 23D are aberration diagrams in the intermediate focal length state at the time of focusing on infinity of the optical system according to the sixth example, FIG. 23A is various aberration diagrams, and FIG. 23B is a lens element. FIG. 23C is a meridional lateral aberration diagram when image blur correction is performed in A, FIG. 23C is a meridional lateral aberration diagram when image blur correction is performed in lens element B, and FIG. It is a meridional lateral aberration diagram when it is performed. 24A, 24B, 24C, and 24D are aberration diagrams in the telephoto end state of the optical system according to Example 6 when focused on infinity, FIG. 24A is various aberration diagrams, and FIG. FIG. 24C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B, and FIG. 24C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B. FIG. It is a meridional transverse aberration diagram at the time. FIG. 25 is a diagram showing an outline of the manufacturing method of the optical system according to the first embodiment of the present invention. FIG. 26 is a diagram showing an outline of the manufacturing method of the optical system according to the first embodiment of the present invention. FIG. 27 is a diagram showing a configuration of an optical system according to Example 7 of Embodiment 2 of the present invention. 28A and 28B are aberration diagrams in the wide-angle end state of the optical system according to Example 7 at the time of focusing on infinity, FIG. 28A is a diagram of various aberrations, and FIG. 28B is an image blur due to the lens element A ′. It is an aberration diagram when correcting. 29A and 29B are aberration diagrams in the intermediate focal length state when the optical system according to Example 7 is focused at infinity, FIG. 29A is various aberration diagrams, and FIG. 29B is an image by the lens element B ′. FIG. 6 is a diagram showing various aberrations when blur correction is performed. 30A and 30B are aberration diagrams of the optical system according to Example 7 in the telephoto end state at the time of focusing on infinity, FIG. 30A is a diagram of various aberrations, and FIG. 30B is an image blur due to the lens element C ′. It is an aberration diagram when correcting. FIG. 31 is a diagram showing a configuration of an optical system according to Example 8 of Embodiment 2 of the present invention. 32A and 32B are aberration diagrams in the wide-angle end state of the optical system according to Example 8 at the time of focusing on infinity, FIG. 32A is a diagram of various aberrations, and FIG. 32B is an image blur due to the lens element A ′. It is an aberration diagram when correcting. 33A and 33B are aberration diagrams in the intermediate focal length state at the time of focusing on infinity of the optical system according to Example 8, FIG. 33A is various aberration diagrams, and FIG. 33b is an image with the lens element A ′. FIG. 6 is a diagram showing various aberrations when blur correction is performed. 34A and 34B are aberration diagrams in the telephoto end state of the optical system according to Example 8 at the infinite focus, FIG. 34A is various aberration diagrams, and FIG. 34B is an image blur due to the lens element B ′. It is an aberration diagram when correcting. FIG. 35 is a diagram showing a configuration of an optical system according to Example 9 of Embodiment 2 of the present invention. FIGS. 36A and 36B are aberration diagrams in the wide-angle end state of the optical system according to Example 9 at the time of focusing on infinity, FIG. 36A is a diagram of various aberrations, and FIG. 36B is an image blur due to the lens element A ′. It is an aberration diagram when correcting. 37A and 37B are aberration diagrams in the intermediate focal length state when the optical system according to Example 9 is focused at infinity, FIG. 37A is various aberration diagrams, and FIG. 37B is an image by the lens element B ′. FIG. 6 is a diagram showing various aberrations when blur correction is performed. 38A and 38B are aberration diagrams in the telephoto end state of the optical system according to Example 9 at the infinite focus, FIG. 38A is various aberration diagrams, and FIG. 38B is an image blur due to the lens element C ′. It is an aberration diagram when correcting. FIG. 39 is a diagram showing a configuration of an optical system according to Example 10 of Embodiment 2 of the present invention. 40A and 40B are aberration diagrams in the wide-angle end state of the optical system according to Example 10 at the time of focusing on infinity, FIG. 40A is a diagram of various aberrations, and FIG. 40B is an image blur due to the lens element A ′. It is an aberration diagram when correcting. 41A and 41B are aberration diagrams in the intermediate focal length state when the optical system according to Example 10 is focused at infinity, FIG. 41A is various aberration diagrams, and FIG. 41B is an image by the lens element A ′. FIG. 6 is a diagram showing various aberrations when blur correction is performed. 42A and 42B are aberration diagrams in the telephoto end state of the optical system according to the tenth example when focused on infinity, FIG. 42A is various aberration diagrams, and FIG. 42B is an image blur due to the lens element B ′. It is an aberration diagram when correcting. FIG. 43 is a diagram showing a configuration of an optical system according to Example 11 of the second embodiment of the present invention. 44A and 44B are aberration diagrams of the optical system according to Example 11 in the wide-angle end state when focused on infinity, FIG. 44A is a diagram of various aberrations, and FIG. 44B is an image blur due to the lens element A ′. It is an aberration diagram when correcting. 45A and 45B are aberration diagrams in the intermediate focal length state at the time of focusing on infinity of the optical system according to Example 11, FIG. 45A is various aberration diagrams, and FIG. 45B is an image by the lens element A ′. FIG. 6 is a diagram showing various aberrations when blur correction is performed. 46A and 46B are aberration diagrams in the telephoto end state of the optical system according to Example 11 when focused on infinity, FIG. 46A is various aberration diagrams, and FIG. 46B is an image blur due to the lens element B ′. It is an aberration diagram when correcting. FIG. 47 is a sectional view schematically showing a digital single-lens reflex camera provided with the optical system of the present invention. FIG. 48 is a diagram showing an outline of a method of manufacturing an optical system according to the second embodiment of the present invention. FIG. 49 is a diagram showing an outline of a method of manufacturing an optical system according to the second embodiment of the present invention. FIG. 50 is a schematic diagram showing an example of the configuration of the image stabilization function in the optical system according to the present invention.

(First embodiment)
Hereinafter, an optical system and an imaging apparatus according to the first embodiment of the present invention will be described.

First, the optical system according to the first embodiment of the present invention will be described. The optical system according to the first embodiment of the present invention is an optical system having a vibration isolation function.

The optical system according to the first embodiment of the present invention includes a first lens element and a second lens element that can be shifted to include a component in a direction perpendicular to the optical axis, and the second lens element includes: It consists of a first lens element and other lens elements. Image blur correction is performed by shifting the first lens element or the second lens element so as to include a component in a direction perpendicular to the optical axis, thereby performing image plane correction.

Here, in this specification, the lens element refers to one unit composed of a single lens or a plurality of lenses.

Whether the first lens element or the second lens element is shifted is determined by the control unit from the amount of image blur detected by an angular velocity sensor or the like provided in the imaging apparatus. FIG. 50 is a schematic diagram showing an example of the configuration of the image stabilization function in the optical system according to the present invention. The control unit 21 calculates an image blur correction amount from the angular velocities detected by the plurality of angular velocity sensors 23, 23, that is, the inclination and orientation of the imaging apparatus main body 31, and the lens element according to the correction amount. Decide which of 25a and 25b to shift. Then, the control unit 21 drives the determined lens element (for example, the lens element 25a) via a driving device 27 such as a motor in a direction that cancels the inclination of the imaging device main body 31. The control unit 21 may be provided in the imaging apparatus main body 31 or may be incorporated in the lens barrel 29 in which the optical system is disposed.

With such a configuration, the optical system according to the first embodiment of the present invention has an effect of having a plurality of image plane correction functions, and an optical system having a suitable image stabilization function can be realized.

In the present invention, an optical system having a more suitable anti-vibration function can be realized under such a configuration.

In addition, the optical system according to the first embodiment of the present invention includes a first lens element and a second lens element that can be shifted so as to include a component in a direction perpendicular to the optical axis. The first lens element and the other lens element have the same refractive power, and the image blur correction includes a component perpendicular to the optical axis of the first lens element or the second lens element. To correct the image plane.

With such a configuration, an optical system having a more suitable image stabilization function can be realized.

Further, by satisfying the following conditional expression (1), it is possible to realize an optical system having a more suitable vibration-proof function.
(1) | fB | <| fA |
However,
| FA |: absolute value of the focal length of the first lens element | fB |: absolute value of the focal length of the second lens element where fA and fB have the same sign

By satisfying conditional expression (1), when the focal length fA of the first lens element and the focal length fB of the second lens element have the same sign, compared to the absolute value of the focal length fA of the first lens element. Since the absolute value of the focal length fB of the second lens element is smaller, even if the amount of movement of the second lens element is the same as the amount of movement of the first lens element, the image plane should be shifted by shifting the second lens element. The amount of movement can be increased. As a result, when the second lens element is shifted and image blur is corrected, more images can be obtained without increasing the amount of lens movement than when the first lens element is shifted and image blur is corrected. Blur correction is possible, and large field curvature aberration can be corrected well.

The optical system according to the first embodiment of the present invention preferably satisfies the following conditional expression (2).
(2) 0.24 <| fB | / | fA | <1.00
However,
| FA |: absolute value of the focal length of the first lens element | fB |: absolute value of the focal length of the second lens element where fA and fB have the same sign

Conditional expression (2) is a conditional expression that defines the focal lengths of the first lens element and the second lens element that perform image plane correction. By satisfying conditional expression (2), when the focal length fA of the first lens element and the focal length fB of the second lens element have the same sign, good optical performance can be realized even during image plane correction. Can do.

If the corresponding value | fB | / | fA | of the conditional expression (2) is less than the lower limit value, it is not preferable because it becomes difficult to correct coma at the time of image plane correction. In order to secure the effect of the present invention, it is preferable to set the lower limit of conditional expression (2) to 0.30.

When the corresponding value | fB | / | fA | of the conditional expression (2) exceeds the upper limit value, the focal length of the first lens element and the focal length of the second lens element that perform image surface correction become close, and as a result, An effect having a plurality of image plane correction functions cannot be obtained, which is not preferable. In order to secure the effect of the present invention, it is preferable to set the upper limit of conditional expression (2) to 0.96.

The optical system according to the first embodiment of the present invention further includes a third lens element that can be shifted so as to include a component in a direction perpendicular to the optical axis, and the third lens element is a second lens element. And another lens element having the same sign as the refractive power of the second lens element, and any one of the first lens element, the second lens element, or the third lens element is placed on the optical axis. The image blur is corrected by shifting so as to include the vertical component. Under such a configuration, an optical system having a more suitable image stabilization function can be realized.

Moreover, it is preferable that the following conditional expression (3) is satisfied.
(3) | fC | <| fB | <| fA |
However,
| FA |: absolute value of the focal length of the first lens element | fB |: absolute value of the focal length of the second lens element | fC |: absolute value of the focal length of the third lens element where fA, fB, and fC Is the same sign

The optical system according to the first embodiment of the present invention can realize an optical system having a more suitable anti-vibration function with such a configuration. The control unit determines which of the first lens element, the second lens element, and the third lens element is to be shifted from the image blur amount detected by the angular velocity sensor or the like, as described with reference to FIG. To do.

In the present invention, an optical system having a more suitable anti-vibration function can be realized by satisfying conditional expression (3) under such a configuration.

By satisfying conditional expression (3), when the focal length fA of the first lens element, the focal length fB of the second lens element, and the focal length fC of the third lens element have the same sign, Since the absolute value of the focal length fC of the third lens element is smaller than the absolute value of the focal length fB, even if the movement amount of the third lens element is the same as that of the second lens element, the third lens The amount of image plane movement can be increased by shifting the element. As a result, when correcting the image blur by shifting the third lens element, more image blur correction is performed without increasing the amount of movement of the lens than when correcting the image blur by shifting the second lens element. Thus, large curvature of field aberration can be corrected satisfactorily.

The optical system according to the first embodiment of the present invention preferably satisfies the following conditional expression (4).
(4) 0.24 <| fC | / | fA | <1.00
However,
| FA |: absolute value of the focal length of the first lens element | fC |: absolute value of the focal length of the third lens element where fA and fC have the same sign

Conditional expression (4) is a conditional expression that defines the focal lengths of the first lens element and the third lens element that perform image plane correction. Satisfying conditional expression (4) makes it possible to achieve good optical performance even during image plane correction.

If the corresponding value | fC | / | fA | of the conditional expression (4) is less than the lower limit value, it is not preferable because coma aberration correction at the time of image plane correction becomes difficult. In order to secure the effect of the present invention, it is preferable to set the lower limit of conditional expression (4) to 0.30.

When the corresponding value | fC | / | fA | of the conditional expression (4) exceeds the upper limit value, the focal lengths of the first lens element, the second lens element, and the third lens element that perform image surface correction become close to each other. As a result, an effect having a plurality of image plane correction functions cannot be obtained, which is not preferable. In order to secure the effect of the present invention, it is preferable to set the upper limit of conditional expression (4) to 0.96.

In the optical system according to the first embodiment of the present invention, it is preferable that the first and second lens elements have cemented lenses. With such a configuration, it is possible to maintain good lateral chromatic aberration during image plane correction.

In the optical system of the present invention, it is preferable that the third lens element has a cemented lens. With such a configuration, it is possible to maintain good lateral chromatic aberration during image plane correction.

The optical system according to the first embodiment of the present invention preferably includes at least four lens groups, and at least the first and second lens elements are included in any one of the four lens groups. . By adopting such a configuration, coma aberration at the time of image plane correction can be reduced.

The optical system according to the first embodiment of the present invention includes, in order from the object side, a first lens group, a second lens group, a third lens group, and a fourth lens group. It is preferable that the distance between the group and the second lens group, the distance between the second lens group and the third lens group, and the distance between the third lens group and the fourth lens group are changed. By adopting such a configuration, it is possible to realize high zoom ratio and correct spherical aberration satisfactorily.

In addition, the optical system according to the first embodiment of the present invention includes a first lens element and a second lens element that can be shifted so as to include a component in a direction perpendicular to the optical axis. The first lens element and the other lens element have different refractive powers, and the first lens element or the second lens element is shifted so as to include a component perpendicular to the optical axis. Perform image plane correction. Under such a configuration, an optical system having a more suitable image stabilization function can be realized.

Moreover, the following conditional expression (5) is satisfied.
(5) | fA | <| fB |
However,
| FA |: Absolute value of the focal length of the first lens element | fB |: Absolute value of the focal length of the second lens element However, fA and fB have different signs

Whether the first lens element or the second lens element is to be shifted is determined by the control unit from the amount of image blur detected by the angular velocity sensor or the like, as described with reference to FIG.

With the above configuration, the optical system according to the first embodiment of the present invention has an effect of having a plurality of image plane correction functions, and an optical system having a suitable image stabilization function can be realized.

In the first embodiment of the present invention, a more suitable optical system can be realized by satisfying conditional expression (5) under such a configuration.

By satisfying conditional expression (5), when fA and fB have different signs, the absolute value of the focal length fA of the first lens element is greater than the absolute value of the focal length fB of the second lens element. Therefore, even if the movement amount of the first lens element is the same as that of the second lens element, the image plane movement amount can be increased by shifting the first lens element. As a result, when correcting the image blur by shifting the first lens element, more image blur correction is performed without increasing the amount of movement of the lens compared to correcting the image blur by shifting the second lens element. Thus, large curvature of field aberration can be corrected satisfactorily.

The optical system according to the first embodiment of the present invention preferably satisfies the following conditional expression (6).
(6) 0.24 <| fA | / | fB | <1.00
However,
| FA |: Absolute value of the focal length of the first lens element | fB |: Absolute value of the focal length of the second lens element However, fA and fB have different signs

Conditional expression (6) is a conditional expression that defines the focal length of the first lens element and the focal length of the second lens element for performing image plane correction. By satisfying conditional expression (6), when fA and fB have different signs, good optical performance can be realized even during image plane correction.

If the corresponding value | fA | / | fB | of the conditional expression (6) is less than the lower limit value, it is not preferable because it becomes difficult to correct coma at the time of image plane correction. In order to secure the effect of the present invention, it is preferable to set the lower limit of conditional expression (6) to 0.30.

When the corresponding value | fA | / | fB | of the conditional expression (6) exceeds the upper limit value, the focal length of the first lens element and the focal length of the second lens element that perform image plane correction become close to each other. The effect of having the image plane correction function cannot be obtained, which is not preferable. In order to secure the effect of the present invention, it is preferable to set the upper limit of conditional expression (6) to 0.96.

In the optical system according to the first embodiment of the present invention, it is preferable that the first and second lens elements have cemented lenses. With such a configuration, it is possible to maintain good lateral chromatic aberration during image plane correction.

The optical system according to the first embodiment of the present invention preferably includes at least four lens groups, and the first and second lens elements are included in any one of the four lens groups. By adopting such a configuration, coma aberration at the time of image plane correction can be reduced.

The optical system according to the first embodiment of the present invention includes, in order from the object side, a first lens group, a second lens group, a third lens group, and a fourth lens group. It is preferable that the distance between the group and the second lens group, the distance between the second lens group and the third lens group, and the distance between the third lens group and the fourth lens group are changed. By adopting such a configuration, it is possible to realize high zoom ratio and correct spherical aberration satisfactorily.

Further, the imaging apparatus according to the first embodiment of the present invention is characterized by having the optical system configured as described above. Thereby, a suitable imaging device can be realized.

Next, a method for manufacturing the optical system according to the first embodiment of the present invention will be described.
25 and 26 are diagrams each schematically showing a method of manufacturing an optical system according to the first embodiment of the present invention.

The optical system manufacturing method according to the first embodiment of the present invention is a method for manufacturing an optical system having a first lens element and a second lens element, as shown in FIG. Includes ST14.

Step ST11: The second lens element is composed of the first lens element and another lens element having a refractive power having the same sign as the refractive power of the first lens element.

Step ST12: The first lens element and the second lens element are arranged so as to be shiftable so as to include a component in a direction perpendicular to the optical axis.

Step ST13: The image plane correction is performed by shifting either the first lens element or the second lens element so as to include a component in a direction perpendicular to the optical axis.

Step ST14: The following conditional expression (1) is satisfied.
(1) | fB | <| fA |
However,
| FA |: absolute value of the focal length of the first lens element | fB |: absolute value of the focal length of the second lens element where fA and fB have the same sign

The optical system manufacturing method according to the first embodiment of the present invention is a method for manufacturing an optical system having a first lens element and a second lens element as shown in FIG. Includes ST21 to ST24.

Step ST21: The second lens element is composed of the first lens element and another lens element having a refractive power different from that of the first lens element.

Step ST22: The first lens element and the second lens element are arranged so as to be shiftable so as to include a component in a direction perpendicular to the optical axis.

Step ST23: The image plane correction is performed by shifting either the first lens element or the second lens element so as to include a component in a direction perpendicular to the optical axis.

Step ST24: The following conditional expression (5) is satisfied.
(5) | fA | <| fB |
However,
| FA |: Absolute value of the focal length of the first lens element | fB |: Absolute value of the focal length of the second lens element However, fA and fB have different signs

According to the method of manufacturing an optical system according to the first embodiment of the present invention, an optical system having a suitable image stabilization function can be manufactured.

(Numerical example)
Hereinafter, an optical system according to a numerical example of the first embodiment of the present invention will be described with reference to the accompanying drawings. 1, FIG. 5, FIG. 9, FIG. 13, FIG. 17, and FIG. 21 are cross-sectional views showing the configurations of the optical systems S1 to S6 according to the respective examples. Infinity focusing of these optical systems S1 to S6 A change in focus state from the wide-angle end state to the telephoto end state at the time, that is, the movement of each lens group is indicated by an arrow.

<First embodiment>
FIG. 1 is a diagram showing a configuration of an optical system S1 according to a first example of the first embodiment of the present invention.

As shown in FIG. 1, the optical system S1 according to the first example includes a first lens group G1 having a positive refractive power and a second lens group G2 having a negative refractive power in order from an object side (not shown). And a third lens group G3 having negative refractive power, an aperture stop SP, and a fourth lens group G4 having positive refractive power.

The first lens group G1 includes, in order from the object side, a cemented lens L11 of a negative meniscus lens having a convex surface facing the object side and a positive meniscus lens having a convex surface facing the object side, and a positive meniscus lens having a convex surface facing the object side. L12.

The second lens group G2 includes, in order from the object side, a cemented lens L21 of a positive meniscus lens having a convex surface facing the object side and a negative meniscus lens having a convex surface facing the object side, and a positive meniscus lens having a concave surface facing the object side. And a cemented lens L22 of a biconcave negative lens.

The third lens group G3 includes, in order from the object side, a cemented lens L31 including a positive meniscus lens having a concave surface facing the object side and a negative meniscus lens having a concave surface facing the object side.

The fourth lens group G4 includes, in order from the object side, a positive meniscus lens L41 having a concave surface directed toward the object side, and a cemented lens L42 of a biconvex positive lens and a negative meniscus lens having a convex surface directed toward the image plane I. , A biconvex positive lens L43, a cemented lens L44 of a positive meniscus lens having a concave surface facing the object side and a biconcave negative lens, a negative meniscus lens L45 having a concave surface facing the object side, and an object side It is composed of a negative meniscus lens L46 having a concave surface and a biconvex positive lens L47.

On the image plane I, an image sensor (not shown) composed of a CCD, a CMOS, or the like is disposed. The aperture stop SP is disposed between the third lens group G3 and the fourth lens group G4. The configurations of the image sensor and the aperture stop SP are the same in each embodiment described later.

In the optical system S1 according to the first example, when zooming from the wide-angle end state to the telephoto end state, the first lens group G1 is fixed with respect to the image plane I, and the second lens group G2 is on the image plane I side. The third lens group G3 moves along a substantially concave locus toward the image plane I side, and the fourth lens group is fixed with respect to the image plane I.

Further, in the optical system S1 according to the first example, as shown in FIG. 1, the cemented lens L44 in the fourth lens group G4 is a lens element A, and has the same sign as the refractive power of the lens element A and the lens element A. The lens element B is composed of a negative meniscus lens L45 having a refractive power, and the lens element C is composed of a lens element B and a negative meniscus lens L46 having the same sign as the refractive power of the lens element B. The element A, the lens element B, and the lens element C are each set as an anti-vibration lens group. Any one of these anti-vibration lens groups is shifted in a direction perpendicular to the optical axis, thereby preventing blurring of the captured image.

In the optical system S1 according to the first example, the focal length of the entire optical system S1 is f, and the ratio of the amount of movement of the image on the image plane I to the amount of movement of the image stabilizing lens group at the time of blur correction is K. When this is done (hereinafter, this ratio is referred to as an anti-vibration coefficient K), in order to correct rotational shake at an angle θ, the lens group for shake correction is set in a direction orthogonal to the optical axis by (f · tan θ) / K. Shift to.

The focal lengths f of the entire system in the wide-angle end state, intermediate focal length state, and telephoto end state of the optical system S1 according to the first example are 95.0 (mm), 163.1 (mm), and 226.6 (respectively). mm) (see Table 1 below). The blur correction amounts by the lens elements A, B, and C and the movement amounts of the lens elements A, B, and C at each focal length are as follows, for example.

In the optical system S1 according to the first example, in the wide-angle end state, the image stabilization coefficient K when the image blur is corrected by the lens element A is 1.26, and the focal length is 95.0 (mm). Therefore, the moving amount of the lens element A for correcting the rotational blur of 0.324 ° is 0.428 (mm). Further, since the image stabilization coefficient K when correcting the image blur by the lens element B is 1.37 and the focal length is 95.0 (mm), it is necessary to correct the rotational blur of 0.354 °. The moving amount of the lens element B is 0.428 (mm). Further, since the image stabilization coefficient K when correcting the image blur by the lens element C is 1.69 and the focal length is 95.0 (mm), it is necessary to correct the rotation blur of 0.435 °. The moving amount of the lens element C is 0.428 (mm).

In the intermediate focal length state of the optical system S1 according to the first example, the image stabilization coefficient K when the image blur is corrected by the lens element A is 1.26, and the focal length is 163.1 (mm). Therefore, the moving amount of the lens element A for correcting the rotational shake of 0.301 ° is 0.680 (mm). Further, since the image stabilization coefficient K when correcting the image blur by the lens element B is 1.37 and the focal length is 163.1 (mm), it is necessary to correct the rotation blur of 0.326 °. The moving amount of the lens element B is 0.680 (mm). Further, since the image stabilization coefficient K when correcting the image blur by the lens element C is 1.69 and the focal length is 163.1 (mm), it is necessary to correct the rotation blur of 0.403 °. The moving amount of the lens element C is 0.680 (mm).

In the telephoto end state of the optical system S1 according to the first example, the image stabilization coefficient K when correcting the image blur by the lens element A is 1.26, and the focal length is 226.6 (mm). Therefore, the movement amount of the lens element A for correcting the rotational blur of 0.210 ° is 0.944 (mm). Further, since the image stabilization coefficient K when correcting the image blur by the lens element B is 1.37 and the focal length is 226.6 (mm), it is necessary to correct the rotation blur of 0.326 °. The moving amount of the lens element B is 0.944 (mm). Further, since the image stabilization coefficient K when correcting the image blur by the lens element C is 1.69 and the focal length is 226.6 (mm), it is necessary to correct the rotation blur of 0.403 °. The moving amount of the lens element C is 0.944 (mm).

In this way, at each focal length, the image stabilization coefficient K increases in the order of the lens element A, the lens element B, and the lens element C, so that more correction is possible. That is, if the focal length is the same and the movement amounts of the lens elements A, B, and C are the same as described above, the lens element B can correct a larger amount than the lens element A. The lens element C can correct a larger amount than the element B. Therefore, when the correction amount is small, the lens element A is driven, and when the correction amount increases and reaches a predetermined amount, the lens element B is driven, and the correction amount further increases and is set to a value larger than the predetermined amount. If the lens element C is controlled to be driven when the other predetermined amount is reached, even if the correction amount increases, more correction can be made without increasing the movement amount of the image stabilizing lens. As a result, from the wide-angle end state to the telephoto end state, the shift amount can be controlled to an appropriate amount without largely shifting the image stabilizing lens group.

Table 1 below lists specification values of the optical system S1 according to the first example of the first embodiment of the present invention.

In Table 1 (overall specifications), f indicates a focal length, FNO indicates an F number, TL indicates a full length, W indicates a wide angle end state, M indicates an intermediate focal length state, and T indicates a telephoto end state. In (surface data), the surface number m is the order of the lens surfaces counted from the object side, r is the radius of curvature of the lens surfaces, d is the distance between the lens surfaces, and nd is the refractive index with respect to the d-line (wavelength λ = 587.6 nm). , Νd represents the Abbe number for the d-line (wavelength λ = 587.6 nm), respectively. The object plane OP is the object plane, (aperture) is the aperture stop SP, and I is the image plane I. Note that the radius of curvature r = ∞ indicates a plane, and the description of the refractive index of air d = 1.00000 is omitted. When the lens surface is an aspheric surface, the surface number is marked with * and the paraxial radius of curvature is shown in the column of the radius of curvature r.

(Aspherical data) shows the paraxial radius of curvature r, conic constant κ, and aspherical coefficients A4 to A12 when the shape of the aspherical surface shown in (Surface data) is expressed by the following equation.

x = (h ² / r) / [1+ {1-κ (h / r) ² } ^1/2 ] + A4h ⁴ + A6h ⁶
+ A8h ⁸ + A10h ¹⁰ + A12h ¹²
Here, x is the displacement in the optical axis direction at the position of the height h from the optical axis when the vertex of the surface is used as a reference. Further, “E−n” indicates “× 10 ⁻ⁿ ”, for example, “1.234E-05” indicates “1.234 × 10 ⁻⁵ ”.

(Variable interval data) indicates the focal length f and the value of the variable interval. (Conditional Expression Corresponding Value) indicates the corresponding value of each conditional expression.

Here, “mm” is generally used as the unit of the focal length f, the radius of curvature r, and other lengths described in Table 1. However, the optical system is not limited to this because an equivalent optical performance can be obtained even when proportionally enlarged or proportionally reduced.

In addition, the code | symbol of Table 1 described above shall be used similarly also in the table | surface of each Example mentioned later.

(Table 1) 1st Example (whole specification)
W M T
f = 95.0 163.1 226.6
FNO = 4.68 4.68 4.70
TL = 259.3 259.3 259.3

(Surface data)
m r d νd nd
op ∞
1) 134.560 1.8 25.43 1.80518
2) 101.277 7.0 82.51 1.49782
3) 546.812 1.0
4) 77.194 4.0 82.51 1.49782
5) 124.044 D5
6) 40.981 5.0 25.68 1.78472
7) 59.996 1.5 40.77 1.88300
8) 36.961 6.7
9) -131.117 3.4 25.43 1.80518
10) -53.784 1.5 40.77 1.88300
11) 197.416 D11
12) -172.226 3.0 27.51 1.75520
13) -80.000 2.0 43.69 1.72000
14) -364.448 D14
15> ∞ 3.0 Aperture
16) -636.174 4.0 82.51 1.49782
17) -57.515 0.3
18) 84.998 6.0 70.45 1.48749
19) -47.705 2.0 35.04 1.74950
20) -289.998 25.9
21) 70.499 4.6 82.56 1.49782
22) -117.909 25.9
23) -188.780 3.5 28.46 1.72825
24) -111.267 1.5 47.38 1.78800
25) 46.602 5.0
26) -119.084 2.0 58.89 1.51823
27) -220.000 5.0
28) -30.419 3.0 64.12 1.51680
29) -48.713 0.2
30) 228.879 5.0 44.79 1.74400
31) -64.531 BF
I ∞

(Variable interval data)
W M T
D5 1.6 46.7 68.9
D11 61.4 2.5 3.4
D14 11.8 25.7 2.7
BF 50.6 50.6 50.6

(Values for conditional expressions)
fA = -46.5
fB = -42.3
fC = -32.5

(1) | fB | <| fA |: 42.3 <46.5
(2) | fB | / | fA | = 0.91
(3) | fC | <| fB | <| fA |: 32.5 <42.3 <46.5
(4) | fC | / | fA | = 0.70

2A, 2B, 2C, and 2D are aberration diagrams in the wide-angle end state of the optical system according to the first example at the time of focusing on infinity, FIG. 2A is a diagram of various aberrations, and FIG. FIG. 2C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B. FIG. 2C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B. FIG. It is a meridional transverse aberration diagram at the time.

3A, 3B, 3C, and 3D are aberration diagrams in the intermediate focal length state at the time of focusing on infinity of the optical system according to the first example, FIG. 3A is various aberration diagrams, and FIG. 3B is a lens element. FIG. 3C is a meridional lateral aberration diagram when image blur correction is performed in A, FIG. 3C is a meridional lateral aberration diagram when image blur correction is performed in the lens element B, and FIG. 3D is image blur correction in the lens element C; It is a meridional lateral aberration diagram when it is performed.

4A, 4B, 4C, and 4D are aberration diagrams in the telephoto end state of the optical system according to the first example when focused on infinity, FIG. 4A is various aberration diagrams, and FIG. FIG. 4C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B, and FIG. 4D is a meridional lateral aberration diagram when image blur correction is performed with the lens element C. It is a meridional transverse aberration diagram at the time.

In each aberration diagram, FNO indicates the F number, and Y indicates the image height. Further, d in the figure indicates an aberration curve at the d-line (wavelength λ = 587.6 nm), and g indicates an aberration curve at the g-line (wavelength λ = 435.8 nm). In the aberration diagram showing astigmatism, the solid line indicates the sagittal image plane, and the broken line indicates the meridional image plane. In addition, in the various aberration diagrams of the following examples, the same reference numerals as those of the present example are used.

As is apparent from each aberration diagram, it can be seen that the first example has excellent imaging performance from the wide-angle end state to the telephoto end state.

<Second embodiment>
FIG. 5 is a diagram showing a configuration of the optical system S2 according to the second example of the first embodiment of the present invention.

As shown in FIG. 5, the optical system S2 according to the second example includes a first lens group G1 having a negative refractive power and a second lens group G2 having a positive refractive power in order from an object side (not shown). The aperture stop SP, the third lens group G3 having a negative refractive power, and the fourth lens group G4 having a positive refractive power.

The first lens group G1 includes, in order from the object side, a negative meniscus lens L11 having a convex surface facing the object side, a biconcave negative lens L12, and a positive meniscus lens L13 having a convex surface facing the object side. The most object-side negative meniscus lens L11 is an aspheric lens in which a resin layer is provided on the glass lens surface on the image plane I side to form an aspheric surface.

The second lens group G2 includes, in order from the object side, a cemented lens L21 of a negative meniscus lens having a convex surface facing the object side and a biconvex positive lens, and a positive meniscus lens L22 having a convex surface facing the object side. Has been.

The third lens group G3 includes, in order from the object side, a cemented lens L31 of a positive meniscus lens having a concave surface facing the object side and a biconcave negative lens, and a plano-concave lens L32 having a concave surface facing the object side. ing.

The fourth lens group G4 includes, in order from the object side, a planoconvex lens L41 having a flat object side, and a cemented lens L42 including a biconvex positive lens and a negative meniscus lens having a convex surface facing the image plane I side. Yes.

On the image plane I, an image sensor (not shown) composed of a CCD, a CMOS, or the like is disposed. The aperture stop SP is disposed between the second lens group G2 and the third lens group G3, and moves together with the third lens group G3 when zooming from the wide-angle end state to the telephoto end state.

In the optical system S2 according to the second example, during zooming from the wide-angle end state to the telephoto end state, the first lens group G1 moves toward the image plane I, and the second lens group G2 and the fourth lens group G4 moves integrally to the object side, and the third lens group G3 moves to the object side.

The optical system S2 according to the second example includes a cemented lens L31 in the third lens group G3 as a lens element A, and a plano-concave lens L32 having the same refractive power as that of the lens element A and the lens element A. The lens element B is composed of the lens element A and the lens element B as a vibration-proof lens group. By shifting any one of these anti-vibration lens groups in a direction orthogonal to the optical axis, blurring of the captured image is prevented.

In the optical system S2 according to the second embodiment, when the focal length of the entire optical system S2 is f and the image stabilization coefficient at the time of blur correction is K, in order to correct the rotational blur at the angle θ, The lens group may be shifted in a direction orthogonal to the optical axis by (f · tan θ) / K.

The focal length f of the entire system in the wide-angle end state, intermediate focal length state, and telephoto end state of the optical system S2 according to the second example is 18.5 (mm), 35.0 (mm), and 53.5 ( mm) (see Table 2 below). The blur correction amount by the lens elements A and B and the movement amount of the lens elements A and B at each focal length are, for example, as follows.

In the optical system S2 according to the second example, in the wide-angle end state, the image stabilization coefficient K when the image blur is corrected by the lens element A is 1.04, and the focal length is 18.5 (mm). Therefore, the moving amount of the lens element A for correcting the rotation blur of 0.735 ° is 0.227 (mm). Further, since the image stabilization coefficient K when correcting the image blur by the lens element B is 1.39 and the focal length is 18.5 (mm), it is necessary to correct the rotation blur of 0.927 °. The moving amount of the lens element B is 0.216 (mm).

Further, in the intermediate focal length state of the optical system S2 according to the second example, the image stabilization coefficient K when correcting the image blur by the lens element A is 1.29, and the focal length is 35.0 (mm). Therefore, the moving amount of the lens element A for correcting the rotational blur of 0.534 ° is 0.252 (mm). In addition, the image stabilization coefficient K when correcting the image blur by the lens element B is 1.71, and the focal length is 35.0 (mm), so that the rotational blur of 0.681 ° is corrected. The moving amount of the lens element B is 0.243 (mm).

In the telephoto end state of the optical system S2 according to the second example, the image stabilization coefficient K when correcting the image blur by the lens element A is 1.66, and the focal length is 53.5 (mm). Therefore, the moving amount of the lens element A for correcting the rotation blur of 0.432 ° is 0.243 (mm). Further, since the image stabilization coefficient K when correcting the image blur by the lens element B is 2.18 and the focal length is 53.5 (mm), it is necessary to correct the rotational blur of 0.553 °. The moving amount of the lens element B is 0.236 (mm).

As described above, since the image stabilization coefficient K increases in the order of the lens element A and the lens element B, more correction can be performed. That is, when the focal length is the same as described above, the lens element B can be corrected by an amount larger than that of the lens element A although the movement amount is smaller than that of the lens element A. Accordingly, if the correction amount is small, the lens element A is driven, and if the correction amount increases and reaches the predetermined amount, the lens element B is controlled so that the vibration-proof lens group moves even if the correction amount increases. More corrections are possible without increasing the amount. As a result, from the wide-angle end state to the telephoto end state, the shift amount can be controlled to an appropriate amount without largely shifting the image stabilizing lens group.

Table 2 below lists specification values of the optical system S2 according to the second example of the first embodiment of the present invention.

(Table 2) Second Example (Overall Specifications)
W M T
f = 18.5 35.0 53.5
FNO = 3.6 4.1 5.3
TL = 130.2 122.3 131.5

(Surface data)
m r d νd nd
op ∞
1) 115.556 1.9 64.12 1.51680
2) 15.601 0.2 38.09 1.55389
* 3) 13.300 10.0
4) -159.479 1.5 58.22 1.62299
5) 35.685 1.1
6) 28.207 3.1 25.68 1.78472
7) 77.398 D7
8) 32.321 0.9 23.78 1.84666
9) 17.691 4.3 58.89 1.51823
10) -32.688 0.1
11) 23.144 1.8 64.10 1.5168
12) 59.408 D12
13> ∞ 2.9 Aperture
14) -40.000 2.75 32.40 1.85026
15) -12.280 0.8 46.60 1.804
16) 114.994 3.0
17) -90.000 1.4 70.50 1.48749
18) ∞ D18
19) ∞ 3.2 52.30 1.51742
20) -21.120 0.1
21) 128.036 5.3 70.50 1.48749
22) -15.933 1.3 32.40 1.85026
23) -44.265 BF
I ∞

(Aspheric data)
Surface number: 3
κ = 1
A4 = 2.63599E-05
A6 = 7.76960E−08
A8 = -1.94524E-10
A10 = 1.27950E-12

(Variable interval data)
W M T
D7 32.3 20.8 9.7
D12 2.6 4.3 8.0
D18 9.6 7.8 4.2
BF 38.1 43.4 52.8

(Values for conditional expressions)
fA = -40.6
fB = -32.6
(1) | fB | <| fA |: 32.6 <40.6
(2) | fB | / | fA | = 0.80

6A, 6B, 6C, and 6D are aberration diagrams in the wide-angle end state of the optical system according to Example 2 at the time of focusing on infinity, FIG. 6A is various aberration diagrams, and FIG. 6B is a lens element A. FIG. 6C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B, and FIG. 6D is a meridional lateral aberration diagram when image blur correction is performed with the lens element C. It is a meridional transverse aberration diagram at the time.

7A, 7B, 7C, and 7D are aberration diagrams in the intermediate focal length state at the time of focusing on infinity of the optical system according to the second example, FIG. 7A is various aberration diagrams, and FIG. 7B is a lens element. FIG. 7C is a meridional lateral aberration diagram when image blur correction is performed in A, FIG. 7C is a meridional lateral aberration diagram when image blur correction is performed in lens element B, and FIG. It is a meridional lateral aberration diagram when it is performed.

8A, 8B, 8C, and 8D are aberration diagrams in the telephoto end state of the optical system according to Example 2 at the time of focusing on infinity, FIG. 8A is various aberration diagrams, and FIG. 8B is a lens element A. FIG. 8C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B, FIG. 8C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B, and FIG. It is a meridional transverse aberration diagram at the time.

As is apparent from each aberration diagram, it can be seen that the second embodiment has excellent imaging performance from the wide-angle end state to the telephoto end state.

<Third embodiment>
FIG. 9 is a diagram showing a configuration of an optical system S3 according to a third example of the first embodiment of the present invention.

As shown in FIG. 9, the optical system S3 according to the third example includes a first lens group G1 having a negative refractive power and a second lens group G2 having a positive refractive power in order from an object side (not shown). The aperture stop SP, the third lens group G3 having a negative refractive power, and the fourth lens group G4 having a positive refractive power.

The first lens group G1 includes, in order from the object side, a negative meniscus lens L11 having a convex surface facing the object side, a biconcave negative lens L12, and a positive meniscus lens L13 having a convex surface facing the object side. The most object-side negative meniscus lens L11 is an aspheric lens in which a resin layer is provided on the glass lens surface on the image plane I side to form an aspheric surface.

The second lens group G2 includes, in order from the object side, a cemented lens L21 of a negative meniscus lens having a convex surface facing the object side and a biconvex positive lens, and a positive meniscus lens L22 having a convex surface facing the object side. Has been.

The third lens group G3 includes, in order from the object side, a cemented lens L31 of a positive meniscus lens having a concave surface facing the object side and a biconcave negative lens, and a plano-concave lens L32 having a concave surface facing the object side. ing.

The fourth lens group G4 includes, in order from the object side, a planoconvex lens L41 having a flat object side, and a cemented lens L42 including a biconvex positive lens and a negative meniscus lens having a convex surface facing the image plane I side. Yes.

On the image plane I, an image sensor (not shown) composed of a CCD, a CMOS, or the like is disposed. The aperture stop SP is disposed between the second lens group G2 and the third lens group G3, and moves together with the third lens group G3 when zooming from the wide-angle end state to the telephoto end state.

In the optical system S3 according to the third example, during zooming from the wide-angle end state to the telephoto end state, the first lens group G1 moves along a convex locus toward the image plane I, and the second lens group G2, The fourth lens group G4 moves integrally to the object side, and the third lens group G3 moves to the object side.

The optical system S3 according to the third example uses a cemented lens L21 in the second lens group G2 as a lens element A, and a positive meniscus lens having a refractive power having the same sign as the refractive power of the lens element A and the lens element A. L22 constitutes a lens element B, and each of the lens element A and the lens element B constitutes a vibration-proof lens group. By shifting any one of these anti-vibration lens groups in a direction orthogonal to the optical axis, blurring of the captured image is prevented.

In the optical system S3 according to the third example, when the focal length of the entire optical system S3 is f and the image stabilization coefficient at the time of shake correction is K, in order to correct the rotational shake at the angle θ, The lens group may be shifted in a direction orthogonal to the optical axis by (f · tan θ) / K.

The focal lengths f of the entire system in the wide-angle end state, the intermediate focal length state, and the telephoto end state of the optical system S3 according to the third example are 18.5 (mm), 35.0 (mm), and 53.5 ( mm) (see Table 3 below). The blur correction amount by the lens elements A and B and the movement amount of the lens elements A and B at each focal length are, for example, as follows.

In the optical system S3 according to the third example, in the wide-angle end state, the image stabilization coefficient K when correcting the image blur by the lens element A is 1.39, and the focal length is 18.5 (mm). Therefore, the movement amount of the lens element A for correcting the rotation blur of 0.735 ° is 0.170 (mm). Further, since the image stabilization coefficient K when correcting the image blur by the lens element B is 1.92 and the focal length is 18.5 (mm), it is necessary to correct the rotational blur of 1.014 °. The moving amount of the lens element B is 0.170 (mm).

Further, in the intermediate focal length state of the optical system S3 according to the third example, the image stabilization coefficient K when the image blur is corrected by the lens element A is 1.80, and the focal length is 35.0 (mm). Therefore, the movement amount of the lens element A for correcting the rotational blur of 0.534 ° is 0.181 (mm). Further, since the image stabilization coefficient K when correcting the image blur by the lens element B is 1.92 and the focal length is 35.0 (mm), it is necessary to correct the rotation blur of 0.742 °. The moving amount of the lens element B is 0.181 (mm).

In the telephoto end state of the optical system S3 according to the third example, the image stabilization coefficient K for correcting image blur by the lens element A is 2.31, and the focal length is 53.5 (mm). Therefore, the moving amount of the lens element A for correcting the rotation blur of 0.432 ° is 0.174 (mm). Further, since the image stabilization coefficient K when correcting the image blur by the lens element B is 3.21 and the focal length is 53.5 (mm), it is necessary to correct the rotation blur of 0.600 °. The moving amount of the lens element B is 0.174 (mm).

As described above, since the image stabilization coefficient K increases in the order of the lens element A and the lens element B, more correction can be performed. That is, if the focal length is the same and the movement amounts of the lens elements A and B are the same as described above, the lens element B can correct a larger amount than the lens element A. Therefore, when the correction amount is small, the lens element A is driven, and when the correction amount increases and reaches a predetermined amount, the lens element B is driven. More corrections can be made without increasing the amount of movement. As a result, from the wide-angle end state to the telephoto end state, the shift amount can be controlled to an appropriate amount without largely shifting the image stabilizing lens group.

Table 3 below lists specification values of the optical system S3 according to the third example of the first embodiment of the present invention.

(Table 3) Third Example (Overall Specifications)
W M T
f = 18.5 35.0 53.5
FNO = 3.6 4.0 5.2
TL = 130.8 121.9 130.2

(Surface data)
m r d νd nd
op ∞
1) 115.450 1.9 64.12 1.51680
2) 15.601 0.2 38.09 1.55389
* 3) 13.300 10.0
4) -145.545 1.5 58.22 1.62299
5) 39.812 1.1
6) 28.306 3.1 25.68 1.78472
7) 67.883 D7
8) 29.022 0.9 23.78 1.84666
9) 16.347 4.3 58.89 1.51823
10) -31.176 0.1
11) 23.440 1.8 64.12 1.51680
12) 59.408 D12
13> ∞ 2.9 Aperture
14) -36.200 2.8 32.35 1.85026
15) -11.078 0.8 46.58 1.80400
16) 114.994 3.0
17) -68.000 1.4 70.45 1.48749
18) ∞ D18
19) -125.598 3.2 52.32 1.51742
20) -20.199 0.1
21) 72.314 5.3 70.45 1.48749
22) -16.608 1.3 32.35 1.85026
23) -44.265 BF
I ∞

(Aspheric data)
Surface number: 3
κ = 1
A4 = 2.71636E-05
A6 = 7.76960E−08
A8 = -1.73581E-10
A10 = 1.27950E-12

(Variable interval data)
W M T
D7 32.3 9.7 2.2
D12 2.6 8.0 12.2
D18 12.1 6.7 2.5
BF 38.1 54.0 67.7

(Values for conditional expressions)
fA = + 39.5
fB = + 25.9
(1) | fB | <| fA |: 25.9 <39.5
(2) | fB | / | fA | = 0.66

FIGS. 10A, 10B, 10C, and 10D are aberration diagrams in the wide-angle end state of the optical system according to Example 3 at the time of focusing on infinity, FIG. 10A is various aberration diagrams, and FIG. FIG. 10C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B. FIG. 10C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B. FIG. It is a meridional transverse aberration diagram at the time.

11A, 11B, 11C, and 11D are aberration diagrams in the intermediate focal length state when the optical system according to Example 3 is focused at infinity, FIG. 11A is various aberration diagrams, and FIG. 11B is a lens element. FIG. 11C is a meridional lateral aberration diagram when image blur correction is performed in A, FIG. 11C is a meridional lateral aberration diagram when image blur correction is performed in lens element B, and FIG. It is a meridional lateral aberration diagram when it is performed.

12A, 12B, 12C, and 12D are aberration diagrams in the telephoto end state of the optical system according to the third example when focused on infinity, FIG. 12A is various aberration diagrams, and FIG. 12B is a lens element A. 12C is a meridional lateral aberration diagram when image blur correction is performed in FIG. 12, FIG. 12C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B, and FIG. 12D is image blur correction performed with the lens element C. It is a meridional transverse aberration diagram at the time.

As is apparent from each aberration diagram, it can be seen that the third example has excellent imaging performance from the wide-angle end state to the telephoto end state.

<Fourth embodiment>
FIG. 13 is a diagram showing a configuration of an optical system S4 according to a fourth example of the first embodiment of the present invention.

As shown in FIG. 13, the optical system S4 according to the fourth example includes a first lens group G1 having a positive refractive power and a second lens group G2 having a negative refractive power in order from an object side (not shown). The aperture stop SP, the third lens group G3 having a positive refractive power, the fourth lens group G4 having a negative refractive power, and the fifth lens group G5 having a positive refractive power.

The first lens group G1 includes, in order from the object side, a cemented lens L11 of a negative meniscus lens having a convex surface facing the object side and a biconvex lens, and a positive meniscus lens L12 having a convex surface facing the object side.

The second lens group G2, in order from the object side, has an aspheric shape on the object side, a negative meniscus lens L21 having a convex surface facing the object side, a biconcave lens L22, a biconvex lens L23, and a concave surface on the object side. And a negative meniscus lens L24 directed to it.

The third lens group G3 includes, in order from the object side, a biconvex lens L31, and a cemented lens L32 of a biconvex lens and a negative meniscus lens having a concave surface facing the object side.

The fourth lens group G4 includes, in order from the object side, a cemented lens L41 of a negative meniscus lens having a convex surface facing the object side and a positive meniscus lens having a convex surface facing the object side, a biconcave lens L42, and a biconcave lens L43. It is configured.

The fifth lens group G5 includes, in order from the object side, a biconvex lens L51 having an aspheric shape on the image plane I side, a biconvex lens L52, and a negative meniscus lens L53 having a concave surface facing the object side. .

On the image plane I, an image sensor (not shown) composed of a CCD, a CMOS, or the like is disposed. The aperture stop SP is disposed between the second lens group G2 and the third lens group G3, and moves together with the third lens group G3 when zooming from the wide-angle end state to the telephoto end state.

The optical system S4 according to the fourth example has a first lens group G1, a second lens group G2, a third lens group G3, a fourth lens group G4, a first lens group G1, a zoom lens when zooming from the wide-angle end state to the telephoto end state. The five lens group G5 moves to the object side.

The optical system S4 according to the fourth example uses a cemented lens L41 in the fourth lens group G4 as a lens element A, and a biconcave lens L42 having the same refractive power as that of the lens element A and the lens element A. The lens element B is constituted by the lens element B, and the lens element C is constituted by the lens element B and the biconcave lens L43 having the same sign as that of the lens element B. The lens element A, the lens element B, and the lens element Each of C is an anti-vibration lens group. By shifting any one of these anti-vibration lens groups in a direction orthogonal to the optical axis, blurring of the captured image is prevented.

In the optical system S4 according to the fourth example, when the focal length of the entire optical system S4 is f and the image stabilization coefficient at the time of blur correction is K, in order to correct the rotational blur at the angle θ, The lens group may be shifted in a direction orthogonal to the optical axis by (f · tan θ) / K.

The focal lengths f of the entire system in the wide-angle end state, the intermediate focal length state, and the telephoto end state of the optical system S4 according to the fourth example are 18.7 (mm), 70.6 (mm), and 188.0 (respectively). mm) (see Table 4 below). The blur correction amounts by the lens elements A, B, and C and the movement amounts of the lens elements A, B, and C at each focal length are as follows, for example.

In the optical system S4 according to the fourth example, in the wide-angle end state, the image stabilization coefficient K when the image blur is corrected by the lens element A is 0.51, and the focal length is 18.7 (mm). Therefore, the moving amount of the lens element A for correcting the rotational shake of 0.623 ° is 0.400 (mm). Further, the image stabilization coefficient K when correcting the image blur by the lens element B is 0.61, and the focal length is 18.7 (mm), so that the rotational blur of 0.746 ° is corrected. The moving amount of the lens element B is 0.400 (mm). Further, since the image stabilization coefficient K when correcting the image blur by the lens element C is 1.69 and the focal length is 18.7 (mm), it is necessary to correct the rotational blur of 1.461 °. The moving amount of the lens element C is 0.400 (mm).

Further, in the intermediate focal length state of the optical system S4 according to the fourth example, the image stabilization coefficient K when the image blur is corrected by the lens element A is 0.82, and the focal length is 70.6 (mm). Therefore, the moving amount of the lens element A for correcting the rotational blur of 0.267 ° is 0.399 (mm). Further, since the image stabilization coefficient K when correcting the image blur by the lens element B is 0.99 and the focal length is 70.6 (mm), it is necessary to correct the rotational blur of 0.321 °. The moving amount of the lens element B is 0.399 (mm). Further, since the image stabilization coefficient K when correcting the image blur by the lens element C is 1.95 and the focal length is 70.6 (mm), it is necessary to correct the rotation blur of 0.630 °. The moving amount of the lens element C is 0.399 (mm).

In the telephoto end state of the optical system S4 according to the fourth example, the image stabilization coefficient K when correcting the image blur by the lens element A is 1.04, and the focal length is 188.0 (mm). Therefore, the moving amount of the lens element A for correcting the rotational blur of 0.126 ° is 0.400 (mm). Further, since the image stabilization coefficient K when correcting the image blur by the lens element B is 1.25 and the focal length is 188.0 (mm), it is necessary to correct the rotational blur of 0.152 °. The moving amount of the lens element B is 0.400 (mm). Further, since the image stabilization coefficient K when correcting the image blur by the lens element C is 2.46 and the focal length is 188.0 (mm), it is necessary to correct the rotation blur of 0.197 °. The moving amount of the lens element C is 0.400 (mm).

As described above, since the image stabilization coefficient K increases in the order of the lens element A, the lens element B, and the lens element C, more correction can be performed. That is, if the focal length is the same and the movement amounts of the lens elements A, B, and C are the same as described above, the lens element B can correct a larger amount than the lens element A. The lens element C can correct a larger amount than the element B. Therefore, when the correction amount is small, the lens element A is driven, and when the correction amount increases and reaches a predetermined amount, the lens element B is driven, and the correction amount further increases and is set to a value larger than the predetermined amount. If the lens element C is controlled to be driven when the other predetermined amount is reached, even if the correction amount increases, more correction can be performed without increasing the movement amount of the image stabilizing lens group. As a result, from the wide-angle end state to the telephoto end state, the shift amount can be controlled to an appropriate amount without largely shifting the image stabilizing lens group.

Table 4 below lists specifications of the optical system S4 according to the fourth example of the first embodiment of the present invention.

(Table 4) Fourth Example (Overall Specifications)
W M T
f = 18.7 70.0 188.0
FNO = 3.64 5.44 6.60
TL = 128.6 180.3 216.7

(Surface data)
m r d νd nd
op ∞
1) 128.56287 1.8 37.18 1.834
2) 61.71903 9.4 82.57 1.49782
3) -368.67603 0.12
4) 55.98016 6.8 82.57 1.49782
5) 389.22661 D5
* 6) 43.51896 1.2 47.25 1.77377
7) 11.20367 6.4
8) -27.87211 1.0 40.66 1.88300
9) 45.04115 0.15
10) 26.85149 4.22 23.8 1.84666
11) -30.94189 1.05
12) -19.31231 1.0 46.6 1.80400
13) -58.68682 D13
14> ∞ 1.63 Aperture
15) 31.09309 3.18 82.57 1.49782
16) -66.2335 0.12
17) 24.20499 4.26 82.57 1.49782
18) -22.11253 0.9 25.45 1.80518
19) -90.15429 D19
20) 90.00000 0.8 52.77 1.74100
21) 15.29423 2.5 25.45 1.80518
22) 33.33188 1.4
23) -450.00000 0.8 63.88 1.51680
24) 459.94923 1.2
25) -80.00000 1.2 54.61 1.72916
26) 183.82631 D26
27) 275.95449 4.0 82.47 1.49697
* 28) -21.43596 0.08
29) 55.21481 4.25 70.31 1.48749
30) -30.00000 1.4
31) -15.80000 1.63 37.18 1.83400
32) -31.79204 BF
I ∞

(Aspheric data)
Surface number: 6
κ = -45.4463
A4 = 6.97E-05
A6 = -5.50E-07
A8 = 3.61E−09
A10 = -1.46E-11
A12 = 2.48E-14
Surface number: 28
κ = -5.3904
A4 = -9.11E-05
A6 = 3.36E-07
A8 = −2.85E−09
A10 = 1.17E-11
A12 = −3.50E-14

(Variable interval data)
W M T
D5 1.0 36.0 56.8
D13 23.1 8.3 1.0
D19 0.9 1.1 2.3
D26 2.9 2.3 2.3
BF 38.7 70.6 92.2

(Values for conditional expressions)
fA = -89.0
fB = -74.1
fC = -37.2
(1) | fB | <| fA |: 74.1 <89.0
(2) | fB | / | fA | = 0.83
(3) | fC | <| fB | <| fA |: 37.2 <74.1 <89.0
(4) | fC | / | fA | = 0.42

14A, 14B, 14C, and 14D are aberration diagrams in the wide-angle end state of the optical system according to Example 4 at the time of focusing on infinity, FIG. 14A is various aberration diagrams, and FIG. FIG. 14C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B, and FIG. 14D is a meridional lateral aberration diagram when image blur correction is performed with the lens element C. It is a meridional transverse aberration diagram at the time.

15A, 15B, 15C, and 15D are aberration diagrams in the intermediate focal length state when the optical system according to Example 4 is focused at infinity, FIG. 15A is various aberration diagrams, and FIG. 15B is a lens element. FIG. 15C is a meridional lateral aberration diagram when image blur correction is performed in A, FIG. 15C is a meridional lateral aberration diagram when image blur correction is performed in lens element B, and FIG. It is a meridional lateral aberration diagram when it is performed.

16A, 16B, 16C, and 16D are aberration diagrams in the telephoto end state of the optical system according to Example 4 when focused on infinity, FIG. 16A is various aberration diagrams, and FIG. FIG. 16C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B, FIG. 16C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B, and FIG. It is a meridional transverse aberration diagram at the time.

As is apparent from each aberration diagram, it can be seen that the fourth example has excellent imaging performance from the wide-angle end state to the telephoto end state.

<Fifth embodiment>
FIG. 17 is a diagram showing a configuration of an optical system S5 according to Example 5 of Embodiment 1 of the present invention.

As shown in FIG. 17, the optical system S5 according to the fifth example includes a first lens group G1 having a positive refractive power and a second lens group G2 having a negative refractive power in order from an object side (not shown). The aperture stop SP, the third lens group G3 having a positive refractive power, and the fourth lens group G4 having a negative refractive power.

The first lens group G1 includes, in order from the object side, a cemented lens L11 of a negative meniscus lens having a convex surface facing the object side and a biconvex lens, and a positive meniscus lens L12 having a convex surface facing the object side.

The second lens group G2, in order from the object side, has an aspheric shape on the object side, a negative meniscus lens L21 having a convex surface facing the object side, a biconcave lens L22, a biconvex lens L23, and a concave surface on the object side. And a negative meniscus lens L24 directed to it.

The third lens group G3 includes, in order from the object side, a biconvex lens L31, and a cemented lens L32 of a biconvex lens and a negative meniscus lens having a concave surface facing the object side.

The fourth lens group G4 includes, in order from the object side, a cemented lens L41 of a biconcave lens and a positive meniscus lens having a convex surface directed toward the object side, a biconcave lens L42, a biconvex lens L43, and an image surface I side having an aspheric shape. It is composed of a positive meniscus lens L44 having a concave surface facing the object side, a biconvex lens L45, and a negative meniscus lens L46 having a concave surface facing the object side.

On the image plane I, an image sensor (not shown) composed of a CCD, a CMOS, or the like is disposed. The aperture stop SP is disposed between the second lens group G2 and the third lens group G3, and moves together with the third lens group G3 when zooming from the wide-angle end state to the telephoto end state.

In the optical system S5 according to the fifth example, during zooming from the wide-angle end state to the telephoto end state, the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 are objects. Move to the side.

Further, in the optical system S5 according to the fifth example, the cemented lens L41 and the biconcave lens L42 in the fourth lens group G4 constitute a lens element A, and the refractive powers of the lens element A and the lens element A are different in sign. A lens element B is constituted by a biconvex lens L43 having refractive power, and each of the lens element A and the lens element B is used as an anti-vibration lens group. By shifting any one of these anti-vibration lens groups in a direction orthogonal to the optical axis, blurring of the captured image is prevented.

In the optical system S5 according to the fifth example, when the focal length of the entire optical system S5 is f and the image stabilization coefficient at the time of shake correction is K, in order to correct the rotational shake at the angle θ, The lens group may be shifted in a direction orthogonal to the optical axis by (f · tan θ) / K.

The focal lengths f of the entire system in the wide-angle end state, the intermediate focal length state, and the telephoto end state of the optical system S5 according to the fifth example are 18.7 (mm), 70.1 (mm), and 188.0, respectively. mm) (see Table 5 below). For example, the blur correction amount by the lens elements A and B and the movement amount of each lens element at each focal length are as follows.

In the optical system S5 according to the fifth example, in the wide-angle end state, the image stabilization coefficient K when correcting the image blur by the lens element A is 1.14, and the focal length is 18.7 (mm). Therefore, the movement amount of the lens element A for correcting the 1.466 ° rotational blur is 0.421 (mm). Further, since the image stabilization coefficient K when correcting the image blur by the lens element B is 0.60 and the focal length is 18.7 (mm), it is necessary to correct the rotation blur of 0.772 °. The moving amount of the lens element B is 0.421 (mm).

Further, in the intermediate focal length state of the optical system S5 according to the fifth example, the image stabilization coefficient K when correcting the image blur by the lens element A is 1.83, and the focal length is 70.1 (mm). Therefore, the movement amount of the lens element A for correcting the rotation blur of 0.630 ° is 0.421 (mm). Further, since the image stabilization coefficient K when correcting the image blur by the lens element B is 0.94 and the focal length is 70.1 (mm), it is necessary to correct the rotation blur of 0.322 °. The moving amount of the lens element B is 0.421 (mm).

In the telephoto end state of the optical system S5 according to the fifth example, the image stabilization coefficient K for correcting image blur by the lens element A is 2.31, and the focal length is 188.0 (mm). Therefore, the movement amount of the lens element A for correcting the rotational shake of 0.296 ° is 0.421 (mm). Further, since the image stabilization coefficient K when correcting the image blur by the lens element B is 1.17 and the focal length is 188.0 (mm), it is necessary to correct the rotation blur of 0.150 °. The moving amount of the lens element B is 0.421 (mm).

As described above, in the fifth embodiment, the image stabilization coefficient K increases in the order of the lens element B and the lens element A. That is, more correction is possible when the image blur is corrected by the lens element A than by the lens element B. As described above, if the focal length is the same and the movement amounts of the lens elements A and B are the same, the lens element A can correct a larger amount than the lens element B. Therefore, when the correction amount is small, the lens element B is driven, and when the correction amount increases and reaches a predetermined amount, the lens element A is driven. More corrections can be made without increasing the amount of movement. As a result, from the wide-angle end state to the telephoto end state, the shift amount can be controlled to an appropriate amount without largely shifting the image stabilizing lens group.

Table 5 below lists specification values of the optical system S5 according to the fifth example of the first embodiment of the present invention.

(Table 5) 5th Example (whole specification)
W M T
f = 18.7 70.1 188.0
FNO = 3.64 5.60 6.97
TL = 130.1 182.0 219.2

(Surface data)
m r d νd nd
op ∞
1) 133.26500 1.4 37.18 1.83400
2) 63.25833 9.2 82.57 1.49782
3) -305.56559 0.12
4) 58.40597 6.4 82.57 1.49782
5) 444.97253 D5
* 6) 45.03974 1.2 47.25 1.77377
7) 11.11015 6.4
8) -24.09331 1.0 40.66 1.88300
9) 68.33997 0.15
10) 31.75544 4.22 23.78 1.84666
11) -28.74651 1.05
12) -17.39728 1.0 46.6 1.80400
13) -38.14366 D13
14> ∞ 1.63 Aperture
15) 26.85327 3.18 82.57 1.49782
16) -48.92537 0.12
17) 28.73946 4.26 82.57 1.49782
18) -24.20835 0.9 25.4 1.80518
19) -150.19371 D19
20) -200.00000 0.8 52.77 1.74100
21) 19.52804 2.5 25.44 1.80518
22) 66.76603 2.0
23) -500.00000 0.8 54.61 1.72916
24) 68.99538 1.2
25) 184.90012 1.9 63.88 1.51680
26) -57.41433 2.3
27) -29.69333 3.0 82.47 1.49697
* 28) -23.59223 0.08
29) 52.67285 4.25 70.31 1.48749
30) -20.13027 1.4
31) -15.95804 1.63 37.18 1.83400
32) -35.63406 BF
I ∞

(Aspheric data)
Surface number: 6
κ = -42.8927
A4 = 6.52E-05
A6 = -4.25E-07
A8 = 2.51E−09
A10 = -9.91E-12
A12 = 1.83E-14
Surface number: 28
κ = -7.2004
A4 = -7.79E-05
A6 = 4.39E-07
A8 = −4.25E−09
A10 = 3.18E-11
A12 = -1.36E-13

(Variable interval data)
W M T
D5 1.0 36.0 56.8
D13 24.8 8.7 1.0
D19 1.5 1.9 3.7
BF 38.7 71.3 93.5

(Values for conditional expressions)
fA = -40.1
fB = -82.5
(5) | fA | <| fB |: 40.1 <82.5
(6) | fA | / | fB | = 0.486

18A, 18B, 18C, and 18D are aberration diagrams in the wide-angle end state of the optical system according to Example 5 at the time of focusing on infinity, FIG. 18A is various aberration diagrams, and FIG. 18B is a lens element A. FIG. 18C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B, FIG. 18C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B, and FIG. It is a meridional transverse aberration diagram at the time.

19A, 19B, 19C, and 19D are aberration diagrams in the intermediate focal length state at the time of focusing on infinity of the optical system according to the fifth example, FIG. 19A is various aberration diagrams, and FIG. 19B is a lens element. FIG. 19C is a meridional lateral aberration diagram when image blur correction is performed at A, FIG. 19C is a meridional lateral aberration diagram when image blur correction is performed at lens element B, and FIG. It is a meridional lateral aberration diagram when it is performed.

20A, 20B, 20C, and 20D are aberration diagrams in the telephoto end state of the optical system according to Example 5 when focused on infinity, FIG. 20A is various aberration diagrams, and FIG. 20B is a lens element A. FIG. 20C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B, and FIG. 20D is a meridional lateral aberration diagram when image blur correction is performed with the lens element C. FIG. It is a meridional transverse aberration diagram at the time.

As is apparent from each aberration diagram, it can be seen that the fifth example has excellent imaging performance from the wide-angle end state to the telephoto end state.

<Sixth embodiment>
FIG. 21 is a diagram showing a configuration of an optical system S6 according to a sixth example of the first embodiment of the present invention.

As shown in FIG. 21, the optical system S6 according to the sixth example includes a first lens group G1 having a positive refractive power and a second lens group G2 having a negative refractive power in order from an object side (not shown). The aperture stop SP, the third lens group G3 having a positive refractive power, the fourth lens group G4 having a negative refractive power, and the fifth lens group G5 having a positive refractive power.

The first lens group G1 includes, in order from the object side, a cemented lens L11 of a negative meniscus lens having a convex surface facing the object side and a positive meniscus lens having a convex surface facing the object side, and a biconvex lens L12.

The second lens group G2, in order from the object side, has an aspheric shape on the object side, a negative meniscus lens L21 having a convex surface facing the object side, a biconcave lens L22, a biconvex lens L23, and a concave surface on the object side. And a negative meniscus lens L24 directed to it.

The third lens group G3 includes, in order from the object side, a biconvex lens L31, and a cemented lens L32 of a biconvex lens and a negative meniscus lens having a concave surface facing the object side.

The fourth lens group G4 includes, in order from the object side, a cemented lens L41 of a negative meniscus lens having a convex surface facing the object side and a positive meniscus lens having a convex surface facing the object side, and a negative meniscus lens having a concave surface facing the object side L42 and a positive meniscus lens L43 having a concave surface facing the object side.

In order from the object side, the fifth lens group G5 has an aspheric shape on the image surface I side, a positive meniscus lens L51 having a concave surface directed to the object side, a biconvex lens L52, and a negative surface having a concave surface directed to the object side. And a meniscus lens L53.

On the image plane I, an image sensor (not shown) composed of a CCD, a CMOS, or the like is disposed. The aperture stop SP is disposed between the second lens group G2 and the third lens group G3, and moves together with the third lens group G3 when zooming from the wide-angle end state to the telephoto end state.

The optical system S6 according to the sixth example has a first lens group G1, a second lens group G2, a third lens group G3, a fourth lens group G4, a first lens group G1, a second lens group G2, and a second lens group G4 when zooming from the wide-angle end state to the telephoto end state. The five lens group G5 moves to the object side.

In the optical system S6 according to the sixth example, the cemented lens L41 and the negative meniscus lens L42 in the fourth lens group G4 constitute a lens element A, and the refractive powers of the lens element A and the lens element A are different from those of the lens element A. The lens element B is composed of a positive meniscus lens L43 having refracting power, and each of the lens element A and the lens element B is used as an anti-vibration lens group. By shifting any one of these anti-vibration lens groups in a direction orthogonal to the optical axis, blurring of the captured image is prevented.

In the optical system S6 according to the sixth example, when the focal length of the entire optical system S6 is f and the image stabilization coefficient at the time of blur correction is K, in order to correct the rotational blur at the angle θ, The lens group may be shifted in a direction orthogonal to the optical axis by (f · tan θ) / K.

The focal lengths f of the entire system in the wide-angle end state, the intermediate focal length state, and the telephoto end state of the optical system S6 according to the sixth example are 18.7 (mm), 70.6 (mm), and 188.0, respectively. mm) (see Table 6 below). For example, the blur correction amount by the lens elements A and B and the movement amount of each lens element at each focal length are as follows.

In the optical system S6 according to the sixth example, in the wide-angle end state, the image stabilization coefficient K when the image blur is corrected by the lens element A is 1.06, and the focal length is 18.7 (mm). Therefore, the moving amount of the lens element A for correcting the rotational blur of 1.446 ° is 0.446 (mm). Further, since the image stabilization coefficient K when correcting the image blur by the lens element B is 0.62 and the focal length is 18.7 (mm), it is necessary to correct the rotation blur of 0.848 °. The moving amount of the lens element B is 0.446 (mm).

Further, in the intermediate focal length state of the optical system S6 according to the sixth example, the image stabilization coefficient K when the image blur is corrected by the lens element A is 1.73, and the focal length is 70.6 (mm). Therefore, the moving amount of the lens element A for correcting the rotational blur of 0.631 ° is 0.446 (mm). Further, since the image stabilization coefficient K when correcting the image blur by the lens element B is 0.99 and the focal length is 70.6 (mm), it is necessary to correct the rotation blur of 0.360 °. The moving amount of the lens element B is 0.446 (mm).

In the telephoto end state of the optical system S6 according to the sixth example, the image stabilization coefficient K when correcting the image blur by the lens element A is 2.21, and the focal length is 188.0 (mm). Therefore, the moving amount of the lens element A for correcting the rotation blur of 0.300 ° is 0.446 (mm). Further, since the image stabilization coefficient K when correcting the image blur by the lens element B is 1.25 and the focal length is 188.0 (mm), it is necessary to correct the rotational blur of 0.169 °. The moving amount of the lens element B is 0.446 (mm).

Thus, in the sixth embodiment, the image stabilization coefficient K increases in the order of the lens element B and the lens element A. That is, more correction is possible when the image blur is corrected by the lens element A than by the lens element B. As described above, if the focal length is the same and the movement amounts of the lens elements A and B are the same, the lens element A can correct a larger amount than the lens element B. Therefore, when the correction amount is small, the lens element B is driven, and when the correction amount increases and reaches a predetermined amount, the lens element A is driven. More corrections can be made without increasing the amount of movement. As a result, from the wide-angle end state to the telephoto end state, the shift amount can be controlled to an appropriate amount without largely shifting the image stabilizing lens group.

Table 6 below lists specifications of the optical system S6 according to the sixth example of the first embodiment of the present invention.

(Table 6) Sixth embodiment (whole specifications)
W M T
f = 18.7 70.0 188.0
FNO = 3.55 5.39 6.91
TL = 129.7 182.7 222.5

(Surface data)
m r d νd nd
op ∞
1) 88.3686 1.4 37.18 1.834
2) 51.2341 9.8 82.57 1.49782
3) 588.9823 0.12
4) 65.0932 6.4 82.57 1.49782
5) -3559.6410 D5
* 6) 37.4711 1.2 47.25 1.77377
7) 10.8979 6.4
8) -29.5092 1.0 40.66 1.88300
9) 58.3390 0.15
10) 26.3202 4.22 23.8 1.84666
11) -34.7037 1.05
12) -18.6800 1.0 46.6 1.80400
13) -67.5427 D13
14> ∞ 1.63 Aperture
15) 23.9912 3.18 82.57 1.49782
16) -62.5375 0.12
17) 33.2119 4.26 82.57 1.49782
18) -21.0524 0.9 25.45 1.80518
19) -74.2470 D19
20) 358.8111 0.8 52.77 1.74100
21) 18.2134 2.5 25.45 1.80518
22) 45.8626 2.0
23) -50.0000 0.8 54.61 1.72916
24) -254.5612 1.2
25) -248.3650 1.9 65.44 1.60300
26) -49.5474 D26
27) -30.0000 4.0 82.47 1.49697
* 28) -20.4714 0.08
29) 43.8397 4.25 70.31 1.48749
30) -31.5343 1.4
31) -16.1983 1.63 37.18 1.83400
32) -30.0990 BF
I ∞

(Aspheric data)
Surface number: 6
κ = -30.2672
A4 = 7.83E-05
A6 = -5.54E-07
A8 = 3.32E−09
A10 = -1.18E-11
A12 = 1.88E-14
Surface number: 28
κ = -4.9613
A4 = -9.15E-05
A6 = 3.67E-07
A8 = -3.27E-09
A10 = 1.76E-11
A12 = -6.39E-14

(Variable interval data)
W M T
D5 1.0 36.0 56.8
D13 23.9 8.3 1.0
D19 0.9 0.9 1.9
D26 1.8 1.8 2.3
BF 38.7 72.4 96.6

(Values for conditional expressions)
fA = -42.2
fB = -76.8
(5) | fA | <| fB |: 42.2 <76.8
(6) | fA | / | fB | = 0.55

22A, 22B, 22C, and 22D are aberration diagrams in the wide-angle end state of the optical system according to Example 6 at the time of focusing on infinity, FIG. 22A is various aberration diagrams, and FIG. 22B is a lens element A. FIG. 22C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B, and FIG. 22D is a meridional lateral aberration diagram when image blur correction is performed with the lens element C. It is a meridional transverse aberration diagram at the time.

23A, 23B, 23C, and 23D are aberration diagrams in the intermediate focal length state at the time of focusing on infinity of the optical system according to the sixth example, FIG. 23A is various aberration diagrams, and FIG. 23B is a lens element. FIG. 23C is a meridional lateral aberration diagram when image blur correction is performed in A, FIG. 23C is a meridional lateral aberration diagram when image blur correction is performed in lens element B, and FIG. It is a meridional lateral aberration diagram when it is performed.

24A, 24B, 24C, and 24D are aberration diagrams in the telephoto end state of the optical system according to Example 6 when focused on infinity, FIG. 24A is various aberration diagrams, and FIG. FIG. 24C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B, and FIG. 24C is a meridional lateral aberration diagram when image blur correction is performed with the lens element B. FIG. It is a meridional transverse aberration diagram at the time.

As is apparent from each aberration diagram, it can be seen that the sixth example has excellent imaging performance from the wide-angle end state to the telephoto end state.

As described above, according to each example of the first embodiment, an optical system having a suitable image stabilization function can be realized.

(Second Embodiment)
Hereinafter, an optical system and an imaging apparatus according to a second embodiment of the present invention will be described.

First, the optical system according to the second embodiment of the present invention will be described. The optical system according to the second embodiment of the present invention is an optical system having a vibration isolation function.

The optical system according to the second embodiment of the present invention includes a first lens element and a second lens element that can be shifted so as to include a component in a direction perpendicular to the optical axis, respectively, from the wide-angle end state to the telephoto end. During zooming to a state, either the first lens element or the second lens element is perpendicular to the optical axis in accordance with a change in focal length from the wide-angle end state to the telephoto end state. Image plane correction is performed by shifting so as to include components.

Here, in this specification, the lens element refers to one unit composed of a single lens or a plurality of lenses.

In general, an anti-vibration lens group that performs image plane correction to correct image blur caused by camera shake or the like has a small shift amount when the optical system is on the wide angle side, and a shift amount that increases as the telephoto side is set. The optical system according to the second embodiment of the present invention can obtain a large image stabilization effect without increasing the shift amount of the image stabilization lens group even on the telephoto side due to the above configuration.

Whether the first lens element or the second lens element is shifted is determined by the control unit from the focal length of the entire optical system at the time of image blur correction. FIG. 50 is a schematic diagram showing an example of the configuration of the image stabilization function in the optical system according to the present invention. The control unit 21 calculates an image blur correction amount from the angular velocities detected by the plurality of angular velocity sensors 23, 23, that is, the magnitude of the inclination of the imaging apparatus main body 31. Further, the control unit 21 determines which of the lens elements 25a and 25b is to be shifted in accordance with the focal length of the entire optical system when correcting the image blur. Then, the control unit 21 drives the determined lens element (for example, the lens element 25a) via a driving device 27 such as a motor in a direction that cancels the inclination of the imaging device main body 31, and performs image plane correction. The control unit 21 may be provided in the imaging apparatus main body 31 or may be incorporated in the lens barrel 29 in which the optical system is disposed.

By adopting such a configuration, the optical system according to the second embodiment of the present invention can satisfactorily correct field curvature aberration at any focal length.

In the present invention, an optical system having a more suitable anti-vibration function can be realized by satisfying the following conditional expressions (7), (8), and (9) under such a configuration.

(7) | fB ′ | <| fA ′ |
(8) fw ≦ fh ≦ (| fB ′ | / | fA ′ |) × ft × 1.50
(9) (| fB ′ | / | fA ′ |) × ft × 0.50 ≦ fk ≦ ft
However,
fA ′: focal length of the first lens element fB ′: focal length of the second lens element fw: focal length of the entire optical system in the wide-angle end state ft: focal length of the entire optical system in the telephoto end state fh: Focal length of the entire optical system when image plane correction is performed by the first lens element fk: Focal length of the entire optical system when image plane correction is performed by the second lens element

Conditional expression (7) defines the focal length of the lens element that performs image plane correction. By satisfying conditional expression (7), the amount of movement of the lens element that performs image plane correction at the time of image plane correction is determined. It is possible to reduce the coma aberration satisfactorily.

Conditional expression (8) is an expression that defines the range of the focal length of the entire optical system when image plane correction is performed with the first lens element. When the conditional expression (8) is satisfied, image plane correction can be performed efficiently. If the value of fh exceeds the upper limit value of the conditional expression (8), the amount of movement of the lens element that performs image plane correction increases, and the coma aberration at the time of image plane correction cannot be satisfactorily corrected.

Conditional expression (9) is an expression that defines the range of the focal length of the entire optical system when image plane correction is performed by the second lens element. By satisfying conditional expression (9), image plane correction can be performed efficiently. If the value of fk is less than the lower limit value of conditional expression (9), the power of the lens element that performs image plane correction is too strong, and the field curvature aberration at the time of image plane correction cannot be corrected well.
In order to secure the effect of the present invention, it is preferable that the upper limit value of conditional expression (8) is (| fB ′ | / | fA ′ |) × ft × 1.15. In order to ensure the effect of the present invention, it is preferable that the lower limit value of conditional expression (9) is (| fB ′ | / | fA ′ |) × ft × 0.70.
The optical system according to the second embodiment of the present invention preferably satisfies the following conditional expression (10).

(10) 0.40 <| ZSw | / | LSw | <1.50
However,
Zsw: the amount of movement of the image on the image plane in the wide-angle end state Lsw: the amount of shift of the lens element that performs image plane correction in the wide-angle end state

When the conditional expression (10) is satisfied, the field curvature aberration can be corrected satisfactorily.

In order to secure the effect of the present invention, it is desirable to set the lower limit of conditional expression (10) to 0.45. In order to secure the effect of the present invention, it is desirable to set the upper limit of conditional expression (10) to 1.40.

Moreover, it is preferable that the optical system according to the second embodiment of the present invention satisfies the following conditional expression (11).

(11) 1.00 <| ZSt | / | LSt | <2.70
However,
ZSt: Amount of image movement on the imaging surface in the telephoto end state LSt: A shift amount of the lens element that performs image plane correction in the telephoto end state

When the conditional expression (11) is satisfied, the field curvature aberration can be corrected satisfactorily.

In order to secure the effect of the present invention, it is desirable to set the lower limit of conditional expression (11) to 1.1. In order to secure the effect of the present invention, it is desirable to set the upper limit of conditional expression (11) to 2.6.

Moreover, it is preferable that the optical system according to the second embodiment of the present invention satisfies the following conditional expressions (12) and (13).

(12) 80.0 <√ (| fA ′ | × fh) / LS <230.0
(13) 80.0 <√ (| fB ′ | × fk) / LS <230.0
However,
fA ′: focal length of the first lens element fB ′: focal length of the second lens element fh: focal length of the entire optical system when image plane correction is performed by the first lens element fk: image plane by the second lens element Focal length of entire optical system when performing correction LS: Shift amount of lens element that performs image plane correction when performing image plane correction

By satisfying the conditional expressions (12) and (13), it is possible to satisfactorily correct the field curvature aberration while keeping the moving amount of the lens element for performing the image surface correction small.

In order to secure the effect of the present invention, it is desirable that the lower limit values of conditional expressions (12) and (13) are 85.0. In order to secure the effect of the present invention, it is desirable that the upper limit values of conditional expressions (12) and (13) are 215.0, respectively.

In the optical system according to the second embodiment of the present invention, it is preferable that the first and second lens elements have cemented lenses. With such a configuration, it is possible to maintain good lateral chromatic aberration during image plane correction.

An optical system according to the second embodiment of the present invention includes a first lens element, a second lens element, and a third lens element that can be shifted so as to include a component in a direction perpendicular to the optical axis. The first lens element, the second lens element, or the third lens element according to a change in focal length from the wide-angle end state to the telephoto end state upon zooming from the wide-angle end state to the telephoto end state The image plane is corrected by shifting so that any one of the components includes a component perpendicular to the optical axis, and the following conditional expressions (14), (15), (16), and (17) It is preferable to satisfy.

(14) | fC ′ | <| fB ′ | <| fA ′ |
(15) fw ≦ fh ≦ (| fC ′ | / | fA ′ |) ft × 0.88
(16) (| fC ′ | / | fA ′ |) × ft × 0.62 ≦ fk ≦ (| fC ′ | / | fB ′ |) × ft × 1.30
(17) (| fC ′ | / | fB ′ |) × ft × 0.92 ≦ fl ≦ ft
However,
fA ′: focal length of the first lens element fB ′: focal length of the second lens element fC ′: focal length of the third lens element fw: focal length of the entire optical system at the wide-angle end ft: optics at the telephoto end Focal length of the entire system fh: Focal length of the entire optical system when image plane correction is performed by the first lens element fk: Focal length of the entire optical system when image plane correction is performed by the second lens element fl: Focal length of the entire optical system when image plane correction is performed with the third lens element

The optical system according to the second embodiment of the present invention can realize an optical system having a suitable anti-vibration function with such a configuration. Which of the first lens element, the second lens element, and the third lens element is to be shifted is the focal length of the entire optical system when correcting image blur, as described with reference to FIG. The control unit 21 determines correspondingly.

Conditional expression (14) defines the focal length of the lens element that performs image plane correction. By satisfying conditional expression (14), it is possible to reduce the amount of movement of the lens element that performs image surface correction at the time of image surface correction, and to correct coma well.

Conditional expression (15) is an expression that defines the range of the focal length of the entire optical system when image plane correction is performed by the first lens element. When the conditional expression (15) is satisfied, the image plane can be corrected efficiently. If the value of fh exceeds the upper limit value of the conditional expression (15), the moving amount of the lens element that performs image plane correction increases, and the coma aberration at the time of image plane correction cannot be corrected favorably.

Conditional expression (16) is an expression that defines the range of the focal length of the entire optical system when image plane correction is performed by the second lens element. When the conditional expression (16) is satisfied, image plane correction can be performed efficiently.

If the value of fk is less than the lower limit value of the conditional expression (16), the power of the lens element that performs image surface correction is too strong, and the field curvature aberration at the time of image surface correction cannot be corrected well.

If the value of fk exceeds the upper limit value of conditional expression (16), the amount of movement of the lens element that performs image surface correction increases, and the coma aberration during image surface correction cannot be corrected well.

Conditional expression (17) is an expression that defines the range of the focal length of the entire optical system when image plane correction is performed by the third lens element. When the conditional expression (17) is satisfied, image plane correction can be performed efficiently.

If the value of f1 is less than the lower limit value of the conditional expression (17), the power of the lens element that performs the image surface correction is too strong, and the field curvature aberration and the coma aberration at the time of image surface correction cannot be corrected well. .

Here, as shown in the conditional expressions (15) and (16), the range of fh defined by the conditional expression (15) (focal length of the entire optical system when image plane correction is performed by the first lens element) And fk (focal length of the entire optical system when image plane correction is performed by the second lens element) defined by the conditional expression (16), there is an overlapping range. The focal length of the entire optical system when the control unit 21 (see FIG. 50) changes the lens element to be shifted from the first lens element to the second lens element or from the second lens element to the first lens element is It is included in this overlapping range. Various control methods can be adopted as to which value within the overlapping range the lens element is changed. For example, the focal length of the entire optical system becomes one predetermined value within the overlapping range, even when zooming from the wide angle side to the telephoto side or when zooming from the telephoto side to the wide angle side. The lens element may be controlled so as to be switched. For example, when zooming from the wide-angle side to the telephoto side, when the lower limit value of the conditional expression (16) is reached, the first lens element is switched to the second lens element, and zooming is performed from the telephoto side to the wide-angle side. If the upper limit of conditional expression (15) is reached, control may be performed so that the second lens element is switched to the first lens element. For example, when the focal length of the entire optical system is within the overlapping range, the control unit 21 randomly selects either the first lens element or the second lens element regardless of the value of the focal length. You may control as follows.

Also in the conditional expressions (16) and (17), the range of fk (focal length of the entire optical system when image plane correction is performed by the second lens element) defined by the conditional expression (16) and the conditional expression (17 ) (The focal length of the entire optical system when image plane correction is performed with the third lens element) defined by (3), there is an overlapping range, but a control method similar to the control method described above is adopted. can do.

In order to secure the effect of the present invention, it is preferable to set the upper limit of conditional expression (15) to (| fC ′ | / | fA ′ |) × ft × 0.85. In order to secure the effect of the present invention, it is preferable that the lower limit value of conditional expression (16) is (| fC ′ | / | fA ′ |) × ft × 0.60. In order to ensure the effect of the present invention, it is preferable that the upper limit value of conditional expression (16) is (| fC ′ | / | fB ′ |) × ft × 1.25. In order to secure the effect of the present invention, it is preferable that the lower limit value of conditional expression (17) is (| fC ′ | / | fB ′ |) × ft × 0.95.

It is preferable that the optical system according to the second embodiment of the present invention satisfies the following conditional expression (18).

(18) 0.40 <| ZSw | / | LSw | <1.40
However,
Zsw: amount of movement of the image on the image plane at the wide-angle end Lsw: shift amount of the lens element that performs image plane correction at the wide-angle end

When the conditional expression (18) is satisfied, the field curvature aberration can be corrected satisfactorily.

Moreover, it is preferable that the optical system according to the second embodiment of the present invention satisfies the following conditional expression (19).

(19) 1.10 <| ZSt | / | LSt | <2.60
However,
ZSt: Amount of image movement on the imaging surface at the telephoto end LSt: A shift amount of the lens element that performs image plane correction at the telephoto end

When the conditional expression (19) is satisfied, the field curvature aberration can be corrected satisfactorily.

Moreover, it is preferable that the optical system according to the second embodiment of the present invention satisfies the following conditional expressions (20), (21), and (22).

(20) 90.0 <√ (| fA ′ | × fh) / LS <230.0
(21) 90.0 <√ (| fB ′ | × fk) / LS <230.0
(22) 90.0 <√ (| fC ′ | × fl) / LS <230.0
However,
fA ′: focal length of the first lens element that performs image plane correction fB ′: focal length of the second lens element that performs image plane correction fC ′: focal length of the third lens element that performs image plane correction fh: first lens Focal length of the entire optical system when performing image surface correction with an element fk: Focal length of the entire optical system when performing image surface correction with a second lens element fl: When performing image surface correction with a third lens element Focal length of the entire optical system LS: shift amount of the lens element that performs the image plane correction when the image plane correction is performed

By satisfying conditional expressions (20), (21), and (22), it is possible to satisfactorily correct the field curvature aberration while keeping the moving amount of the lens element that performs the image surface correction small.

In the optical system according to the second embodiment of the present invention, it is preferable that each of the first lens element, the second lens element, and the third lens element has a cemented lens. With such a configuration, it is possible to maintain good lateral chromatic aberration during image plane correction.

Further, an imaging apparatus according to the second embodiment of the present invention is characterized by having the optical system having the above-described configuration. Thereby, a suitable imaging device can be realized.

Next, a method for manufacturing a photographic lens according to the second embodiment of the present invention will be described.
48 and 49 are diagrams showing an outline of the method of manufacturing the optical system according to the second embodiment of the present invention.

The method for manufacturing an optical system according to the second embodiment of the present invention is a method for manufacturing an optical system having a first lens element and a second lens element, and as shown in FIG. Includes ST33.

Step ST31: The first lens element and the second lens element are configured to be shiftable so as to include a component in a direction perpendicular to the optical axis.

Step ST32: At the time of zooming from the wide-angle end state to the telephoto end state, either the first lens element or the second lens element is changed according to a change in focal length from the wide-angle end state to the telephoto end state. The image plane is corrected by shifting so as to include a component in a direction perpendicular to the optical axis.

Step ST33: The following conditional expressions (7), (8), and (9) are satisfied.
(7) | fB ′ | <| fA ′ |
(8) fw ≦ fh ≦ (| fB ′ | / | fA ′ |) × ft × 1.50
(9) (| fB ′ | / | fA ′ |) × ft × 0.50 ≦ fk ≦ ft
However,
fA ′: focal length of the first lens element fB ′: focal length of the second lens element fw: focal length of the entire optical system in the wide-angle end state ft: focal length of the entire optical system in the telephoto end state fh: Focal length of the entire optical system when image plane correction is performed by the first lens element fk: Focal length of the entire optical system when image plane correction is performed by the second lens element

Further, the optical system manufacturing method according to the second embodiment of the present invention is a method of manufacturing an optical system having a first lens element, a second lens element, and a third lens element, as shown in FIG. The following steps ST41 to ST42 are included.

Step ST41: The first lens element, the second lens element, and the third lens element are configured to be shiftable so as to include a component in a direction perpendicular to the optical axis.

Step ST42: Upon zooming from the wide-angle end state to the telephoto end state, the first lens element, the second lens element or the third lens element is changed according to a change in focal length from the wide-angle end state to the telephoto end state. Any one of the lens elements is configured to perform image plane correction by shifting so as to include a component in a direction perpendicular to the optical axis.

A suitable optical system can be realized by the method for manufacturing an optical system according to the second embodiment of the present invention.

(Numerical example)
Hereinafter, an optical system according to a numerical example of the second embodiment of the present invention will be described with reference to the accompanying drawings. FIGS. 27, 31, 35, 39, and 43 are cross-sectional views showing the configurations of the optical systems S7 to S11 according to the respective examples of the second embodiment, and the infinity of these optical systems S7 to S11 is shown. A change in the in-focus state from the wide-angle end state to the telephoto end state in the in-focus state, that is, the movement of each lens group is indicated by an arrow.

<Seventh embodiment>
FIG. 27 is a diagram showing a configuration of an optical system S7 according to a seventh example of the second embodiment of the present invention.

As shown in FIG. 27, the optical system S7 according to the seventh example includes a first lens group G1 having a positive refractive power and a second lens group G2 having a negative refractive power in order from an object side (not shown). And a third lens group G3 having negative refractive power, an aperture stop SP, and a fourth lens group G4 having positive refractive power.

The first lens group G1 includes, in order from the object side, a cemented lens L11 of a negative meniscus lens having a convex surface facing the object side and a positive meniscus lens having a convex surface facing the object side, and a positive meniscus lens having a convex surface facing the object side. L12.

The second lens group G2 includes, in order from the object side, a cemented lens L21 of a positive meniscus lens having a convex surface facing the object side and a negative meniscus lens having a convex surface facing the object side, and a positive meniscus lens having a concave surface facing the object side. And a cemented lens L22 of a biconcave negative lens.

The third lens group G3 includes, in order from the object side, a cemented lens L31 including a positive meniscus lens having a concave surface facing the object side and a negative meniscus lens having a concave surface facing the object side.

The fourth lens group G4 includes, in order from the object side, a positive meniscus lens L41 having a concave surface directed toward the object side, and a cemented lens L42 of a biconvex positive lens and a negative meniscus lens having a convex surface directed toward the image plane I. , A biconvex positive lens L43, a cemented lens L44 of a positive meniscus lens having a concave surface facing the object side and a biconcave negative lens, a negative meniscus lens L45 having a concave surface facing the object side, and an object side It is composed of a negative meniscus lens L46 having a concave surface and a biconvex positive lens L47.

On the image plane I, an image sensor (not shown) composed of a CCD, a CMOS, or the like is disposed. The aperture stop SP is disposed between the third lens group G3 and the fourth lens group G4. The configurations of the image sensor and the aperture stop SP are the same in each embodiment described later.

In the optical system S7 according to the seventh example, the first lens group G1 is fixed with respect to the image plane I and the second lens group G2 is on the image plane I side when zooming from the wide-angle end state to the telephoto end state. The third lens group G3 moves along a substantially concave locus toward the image plane I side, and the fourth lens group is fixed with respect to the image plane I.

In addition, as shown in FIG. 27, the optical system S7 according to the seventh example uses the cemented lens L44 in the fourth lens group G4 as a lens element A ′, and the refractive powers of the lens element A ′ and the lens element A ′. The lens element B ′ is composed of the negative meniscus lens L45 having the same sign as the refractive power, and the lens element C is composed of the lens element B ′ and the negative meniscus lens L46 having the same sign as the refractive power of the lens element B ′. The lens element A ′, the lens element B ′, and the lens element C ′ are used as an anti-vibration lens group. Any one of these anti-vibration lens groups is shifted so as to include a component in a direction perpendicular to the optical axis, thereby preventing blurring of the captured image.

In the optical system S7 according to the seventh example, f is the focal length of the entire optical system S7, and K is the ratio of the amount of movement of the image on the image plane I to the amount of movement of the image stabilizing lens group during blur correction. When this is done (hereinafter, this ratio is referred to as an anti-vibration coefficient K), in order to correct rotational shake at an angle θ, the lens group for shake correction is set in a direction orthogonal to the optical axis by (f · tan θ) / K. Shift to.

The focal lengths f of the entire system in the wide-angle end state, intermediate focal length state, and telephoto end state of the optical system S7 according to Example 7 are 95.0 (mm), 163.1 (mm), and 226.6 (respectively). mm) (see Table 1 below). The blur correction amount by any of the lens elements A ′, B ′, and C ′ at each focal length and the movement amount of the lens element at that time are as follows, for example.

In the optical system S7 according to the seventh example, in the wide-angle end state, the image stabilization coefficient K when correcting the image blur by the lens element A ′ is 1.26, and the focal length is 95.0 (mm). Therefore, the moving amount of the lens element A ′ for correcting the rotation blur of 0.324 ° is 0.428 (mm).

In the intermediate focal length state of the optical system S7 according to the seventh example, the image stabilization coefficient K when correcting the image blur by the lens element B ′ is 1.37, and the focal length is 163.1 ( mm), the movement amount of the lens element B ′ for correcting the rotational blur of 0.247 ° is 0.515 (mm). Here, when the same rotation blur correction is performed by the lens element A ′ in the intermediate focal length state, the image stabilization coefficient K is 1.26 and the focal length is 163.1 (mm). The amount of movement of the lens element A ′ for correcting rotational blur of 0.247 ° is 0.558 (mm). Therefore, if the amount of blur correction is the same, the amount of movement of the image stabilizing lens group is smaller when the correction is performed using the lens element B 'than when the correction is performed using the lens element A'.

Further, in the telephoto end state of the optical system S7 according to the seventh example, the image stabilization coefficient K when correcting the image blur by the lens element C ′ is 1.69, and the focal length is 226.6 (mm). Therefore, the movement amount of the lens element C ′ for correcting the rotational blur of 0.210 ° is 0.492 (mm). Here, when the same rotation blur correction is performed by the lens element A ′ in the telephoto end state, the image stabilization coefficient K is 1.26 and the focal length is 226.6 (mm). The moving amount of the lens element A ′ for correcting the rotational blur of 0.210 ° is 0.659 (mm). Further, when the lens element B ′ is used, the image stabilization coefficient K is 1.37 and the focal length is 226.6 (mm). Therefore, a lens for correcting rotational blur of 0.210 °. The amount of movement of the element B ′ is 0.606 (mm). Therefore, if the blur correction amount is the same, the amount of movement of the image stabilizing lens group is smaller when the correction is performed by the lens element C 'than when the correction is performed by the lens element A' or B '.

Thus, since the image stabilization coefficient K increases in the order of the lens element A ′, the lens element B ′, and the lens element C ′, more correction can be performed. That is, if the movement amounts of the lens elements A ′, B ′, and C ′ are the same when the focal length of the entire system is the same, the lens element B ′ can correct a larger amount than the lens element A ′. Further, the lens element C ′ can correct a larger amount than the lens element B ′. In other words, if the focal length is the same and the blur correction amount is the same, the lens element B ′ can reduce the movement amount of the vibration-proof lens group than the lens element A ′, and the lens element B The lens element C can reduce the amount of movement of the image stabilizing lens group than the lens element C. Therefore, if the lens element A ′ is driven on the wide-angle end side and controlled so that the lens elements B ′ and C ′ are sequentially driven as the magnification is changed to the telephoto end side, the focal length becomes longer and the blur correction amount increases. Even if the number is increased, more corrections can be made without increasing the amount of movement of the image stabilizing lens group. As a result, from the wide-angle end state to the telephoto end state, the shift amount can be controlled to an appropriate amount without largely shifting the image stabilizing lens group.

Table 7 below lists specifications of the optical system S7 according to the seventh example of the second embodiment of the present invention.

(Table 7) Seventh Example (whole specifications)
W M T
f = 95.0 163.1 226.6
FNO = 4.68 4.68 4.70
TL = 259.3 259.3 259.3
fh = 95.0-110.0
fk = 110.0-170.0
fl = 170.0-226.6

(Surface data)
m r d νd nd
op ∞
1) 134.560 1.8 25.43 1.80518
2) 101.277 7.0 82.51 1.49782
3) 546.812 1.0
4) 77.194 4.0 82.51 1.49782
5) 124.044 D5
6) 40.981 5.0 25.68 1.78472
7) 59.996 1.5 40.77 1.88300
8) 36.961 6.7
9) -131.117 3.4 25.43 1.80518
10) -53.784 1.5 40.77 1.88300
11) 197.416 D11
12) -172.226 3.0 27.51 1.75520
13) -80.000 2.0 43.69 1.72000
14) -364.448 D14
15> ∞ 3.0 Aperture
16) -636.174 4.0 82.51 1.49782
17) -57.515 0.3
18) 84.998 6.0 70.45 1.48749
19) -47.705 2.0 35.04 1.74950
20) -289.998 25.9
21) 70.499 4.6 82.56 1.49782
22) -117.909 25.9
23) -188.780 3.5 28.46 1.72825
24) -111.267 1.5 47.38 1.78800
25) 46.602 5.0
26) -119.084 2.0 58.89 1.51823
27) -220.000 5.0
28) -30.419 3.0 64.12 1.51680
29) -48.713 0.2
30) 228.879 5.0 44.79 1.74400
31) -64.531 BF
I ∞

(Variable interval data)
W M T
D5 1.6 46.7 68.9
D11 61.4 2.5 3.4
D14 11.8 25.7 2.7
BF 50.6 50.6 50.6

(Values for conditional expressions)
fA '=-46.5
fB '=-42.3
fC '=-32.5
fw = 95.0
ft = 226.6
fh = 95.0-138.9
fk = 97.9-225.8
fl = 159.7-226.6
ZSw = 0.538
LSw = -0.428
ZSt = 0.830
LSt = -0.492
LS = −0.428: Image plane correction with lens element A ′ = − 0.515: Image plane correction with lens element B ′ = − 0.492: Image plane correction with lens element C ′ (14) | fC ′ | <| fB ′ | < | FA '|
32.5 <42.3 <46.5
(15) fw ≦ fh ≦ (| fC ′ | / | fA ′ |) × ft × 0.88:
95.0 ≤ 95.0-138.9 ≤ 138.9
(16) (| fC ′ | / | fA ′ |) × ft × 0.62 ≦ fk ≦ (| fC ′ | / | fB ′ |) × ft × 1.30:
97.9 ≤ 97.9-225.8 ≤ 225.8
(17) (| fC ′ | / | fB ′ |) × ft × 0.92 ≦ fl ≦ ft:
159.7 ≤ 159.7-226.6 ≤ 226.6
(18) | ZSw | / | LSw | = 1.26
(19) | ZSt | / | LSt | = 1.69
(20) √ (| fA ′ | × fh) /LS=155.3
(21) √ (| fB ′ | × fk) /LS=161.2
(22) √ (| fC ′ | × fl) /LS=154.8

28A and 28B are aberration diagrams in the wide-angle end state of the optical system according to Example 7 at the time of focusing on infinity, FIG. 28A is a diagram of various aberrations, and FIG. 28B is an image blur due to the lens element A ′. It is an aberration diagram when correcting. 29A and 29B are aberration diagrams in the intermediate focal length state when the optical system according to Example 7 is focused at infinity, FIG. 29A is various aberration diagrams, and FIG. 29B is an image by the lens element B ′. FIG. 6 is a diagram showing various aberrations when blur correction is performed. 30A and 30B are aberration diagrams of the optical system according to Example 7 in the telephoto end state at the time of focusing on infinity, FIG. 30A is a diagram of various aberrations, and FIG. 30B is an image blur due to the lens element C ′. It is an aberration diagram when correcting.

As is apparent from each aberration diagram, it can be seen that in the seventh example, various aberrations are well corrected from the wide-angle end state to the telephoto end state, and the imaging performance is excellent.

<Eighth embodiment>
FIG. 31 is a diagram showing a configuration of an optical system S8 according to an eighth example of the second embodiment of the present invention.

As shown in FIG. 31, the optical system S8 according to the eighth example includes a first lens group G1 having a negative refractive power and a second lens group G2 having a positive refractive power in order from an object side (not shown). The aperture stop SP, the third lens group G3 having a negative refractive power, and the fourth lens group G4 having a positive refractive power.

The first lens group G1 includes, in order from the object side, a negative meniscus lens L11 having a convex surface facing the object side, a biconcave negative lens L12, and a positive meniscus lens L13 having a convex surface facing the object side. The most object-side negative meniscus lens L11 is an aspheric lens in which a resin layer is provided on the glass lens surface on the image plane I side to form an aspheric surface.

The second lens group G2 includes, in order from the object side, a cemented lens L21 including a negative meniscus lens having a convex shape on the object side and a positive lens having a biconvex shape, and a positive meniscus lens L22 having a convex shape on the object side. Yes.

The third lens group G3 includes, in order from the object side, a cemented lens L31 of a positive meniscus lens having a concave surface facing the object side and a biconcave negative lens, and a plano-concave lens L32 having a concave surface facing the object side. ing.

The fourth lens group G4 includes, in order from the object side, a planoconvex lens L41 having a flat object side, and a cemented lens L42 including a biconvex positive lens and a negative meniscus lens having a convex surface facing the image plane I side. Yes.

On the image plane I, an image sensor (not shown) composed of a CCD, a CMOS, or the like is disposed. The aperture stop SP is disposed between the second lens group G2 and the third lens group G3, and moves together with the third lens group G3 when zooming from the wide-angle end state to the telephoto end state.

In the optical system S8 according to the eighth example, during zooming from the wide-angle end state to the telephoto end state, the first lens group G1 moves toward the image plane I, and the second lens group G2 and the fourth lens group G4 moves integrally to the object side, and the third lens group G3 moves to the object side.

In the optical system S8 according to the eighth example, the cemented lens L31 and the plano-concave lens L32 in the third lens group G3 are the lens element A ′, and the cemented lens L21 in the second lens group G2 is the lens element B ′. These lens element A ′ and lens element B ′ are used as an anti-vibration lens group. By shifting any one of these anti-vibration lens groups in a direction orthogonal to the optical axis, blurring of the captured image is prevented.

In the optical system S8 according to the eighth example, when the focal length of the entire optical system S8 is f and the image stabilization coefficient at the time of blur correction is K, in order to correct the rotational blur at the angle θ, The lens group may be shifted in a direction orthogonal to the optical axis by (f · tan θ) / K.

The focal lengths f of the entire system in the wide-angle end state, the intermediate focal length state, and the telephoto end state of the optical system S8 according to the eighth example are 18.5 (mm), 35.0 (mm), and 53.5 ( mm) (see Table 8 below). The blur correction amount by the lens element A ′ or B ′ at each focal length and the movement amount of the lens element at that time are as follows, for example.

In the optical system S8 according to the eighth example, in the wide-angle end state, the image stabilization coefficient K for correcting the image blur by the lens element A ′ is 1.27, and the focal length is 18.5 (mm). Therefore, the moving amount of the lens element A ′ for correcting the rotation blur of 0.735 ° is 0.187 (mm).

In the intermediate focal length state of the optical system S8 according to the eighth example, the image stabilization coefficient K when correcting the image blur by the lens element A ′ is 1.58, and the focal length is 35.0 ( mm), the movement amount of the lens element A ′ for correcting the rotational blur of 0.534 ° is 0.206 (mm).

In the telephoto end state of the optical system S8 according to the eighth example, the image stabilization coefficient K when correcting the image blur by the lens element B ′ is 2.04, and the focal length is 53.5 (mm). Therefore, the movement amount of the lens element B ′ for correcting the rotational blur of 0.432 ° is 0.198 (mm). Here, when the same rotational blur correction is performed by the lens element A ′ in the telephoto end state, the image stabilization coefficient K is 1.66 and the focal length is 53.5 (mm). The movement amount of the lens element A ′ for correcting the rotational blur of 0.432 ° is 0.243 (mm). Therefore, if the amount of blur correction is the same, the amount of movement of the image stabilizing lens group is smaller when the correction is performed using the lens element B 'than when the correction is performed using the lens element A'.

As described above, in the eighth embodiment, since the image stabilization coefficient K increases in the order of the lens element A ′ and the lens element B ′, more correction is possible. That is, in the state where the focal length of the entire system is the same, if the movement amount of the lens elements A ′ and B ′ is the same, the lens element B ′ can be corrected more than the lens element A ′. In other words, if the blur correction amount is the same, the lens element B ′ can reduce the movement amount of the image stabilizing lens group compared to the lens element A ′. Therefore, if the lens element A ′ is driven when the focal length ranges from the wide-angle end state to the intermediate focal length state, and the lens element B ′ is driven further toward the telephoto end side, the focal length becomes longer. Even if the amount of blur correction increases, more correction can be performed without increasing the amount of movement of the image stabilizing lens group. As a result, from the wide-angle end state to the telephoto end state, it is possible to control the shift amount to be an appropriate amount without greatly shifting the image stabilizing lens.

Table 8 below lists specifications of the optical system S8 according to the eighth example of the second embodiment of the present invention.

(Table 8) Eighth Example (Overall Specifications)
W M T
f = 18.5 35.0 53.5
FNO = 3.6 4.1 5.3
TL = 130.2 122.3 131.5
fh = 18.5-44.65
fk = 44.65-53.5

(Surface data)
m r d νd nd
op ∞
1) 115.556 1.9 64.12 1.51680
2) 15.601 0.2 38.09 1.55389
* 3) 13.300 10.0
4) -159.479 1.5 58.22 1.62299
5) 35.685 1.1
6) 28.207 3.1 25.68 1.78472
7) 77.398 2.2
8) 32.321 0.9 23.78 1.84666
9) 17.691 4.3 58.89 1.51823
10) -32.688 0.1
11) 23.144 1.8 64.10 1.5168
12) 59.408 D12
13> ∞ 2.9 Aperture
14) -40.000 2.75 32.40 1.85026
15) -12.280 0.8 46.60 1.804
16) 114.994 3.0
17) -90.000 1.4 70.50 1.48749
18) ∞ D18
19) ∞ 3.2 52.30 1.51742
20) -21.120 0.1
21) 128.036 5.3 70.50 1.48749
22) -15.933 1.3 32.40 1.85026
23) -44.265 BF
I ∞

(Aspheric data)
Surface number: 3
κ = 1
A4 = 2.63599E-05
A6 = 7.76960E−08
A8 = -1.94524E-10
A10 = 1.27950E-12

(Variable interval data)
W M T
D7 32.3 20.8 9.7
D12 2.6 4.3 8.0
D18 9.6 7.8 4.2
BF 38.1 43.4 52.8

(Values for conditional expressions)
fA '=-32.6
fB '= 27.2
fw = 18.5
ft = 53.5
fh = 18.5-44.65
fk = 44.65-53.5
ZSw = 0.237
LSw = -0.187
ZSt = 0.403
LSt = 0.198
LS = −0.187: Image plane correction with lens element A ′ = − 0.198: Image plane correction with lens element B ′ (7) | fB ′ | <| fA ′ |:
27.2 <32.6
(8) fw ≦ fh ≦ (| fB ′ | / | fA ′ |) × ft × 1.50:
18.5 ≤ 18.5 to 44.65 ≤ 44.65
(9) (| fB ′ | / | fA ′ |) × ft × 0.50 ≦ fk ≦ ft:
44.65 ≤ 44.65-53.5 ≤ 53.5
(10) | ZSw | / | LSw | = 1.27
(11) | ZSt | / | LSt | = 2.04
(12) √ (| fA ′ | × fh) /LS=131.4
(13) √ (| fB ′ | × fk) /LS=192.7

32A and 32B are aberration diagrams in the wide-angle end state of the optical system according to Example 8 at the time of focusing on infinity, FIG. 32A is a diagram of various aberrations, and FIG. 32B is an image blur due to the lens element A ′. It is an aberration diagram when correcting. 33A and 33B are aberration diagrams in the intermediate focal length state at the time of focusing on infinity of the optical system according to Example 8, FIG. 33A is various aberration diagrams, and FIG. 33b is an image with the lens element A ′. FIG. 6 is a diagram showing various aberrations when blur correction is performed. 34A and 34B are aberration diagrams in the telephoto end state of the optical system according to Example 8 at the infinite focus, FIG. 34A is various aberration diagrams, and FIG. 34B is an image blur due to the lens element B ′. It is an aberration diagram when correcting.

As is apparent from the respective aberration diagrams, it can be seen that in the eighth example, various aberrations are corrected well from the wide-angle end state to the telephoto end state, and the imaging performance is excellent.

<Ninth embodiment>
FIG. 35 is a diagram showing a configuration of an optical system S9 according to Example 9 of Embodiment 2 of the present invention.

As shown in FIG. 35, the optical system S9 according to the ninth example includes a first lens group G1 having a positive refractive power and a second lens group G2 having a negative refractive power in order from an object side (not shown). The aperture stop SP, the third lens group G3 having a positive refractive power, the fourth lens group G4 having a negative refractive power, and the fifth lens group G5 having a positive refractive power.

The first lens group G1 includes, in order from the object side, a cemented lens L11 of a negative meniscus lens having a convex surface facing the object side and a biconvex lens, and a positive meniscus lens L12 having a convex surface facing the object side.

The second lens group G2, in order from the object side, has an aspheric shape on the object side, a negative meniscus lens L21 having a convex surface facing the object side, a biconcave lens L22, a biconvex lens L23, and a concave surface on the object side. And a negative meniscus lens L24 directed to it.

The third lens group G3 includes, in order from the object side, a biconvex lens L31, and a cemented lens L32 of a biconvex lens and a negative meniscus lens having a concave surface facing the object side.

The fourth lens group G4 includes, in order from the object side, a cemented lens L41 of a negative meniscus lens having a convex surface facing the object side and a positive meniscus lens having a convex surface facing the object side, a biconcave lens L42, and a biconcave lens L43. It is configured.

The fifth lens group G5 includes, in order from the object side, a biconvex lens L51 having an aspheric shape on the image plane I side, a biconvex lens L52, and a negative meniscus lens L53 having a concave surface facing the object side. .

On the image plane I, an image sensor (not shown) composed of a CCD, a CMOS, or the like is disposed. The aperture stop SP is disposed between the second lens group G2 and the third lens group G3, and moves together with the third lens group G3 when zooming from the wide-angle end state to the telephoto end state.

The optical system S9 according to the ninth example has a first lens group G1, a second lens group G2, a third lens group G3, a fourth lens group G4, a first lens group G1, a second lens group G2, and a fourth lens group G4, during zooming from the wide-angle end state to the telephoto end state. The five lens group G5 moves to the object side.

The optical system S9 according to the ninth example uses the cemented lens L41 in the fourth lens group G4 as a lens element A ′, and has a refractive power having the same sign as the refractive power of the lens element A ′ and the lens element A ′. A lens element B ′ is composed of the biconcave lens L42, and a lens element C ′ is composed of the lens element B ′ and the biconcave lens L43 having the same refractive power as that of the lens element B ′. ', Lens element B' and Lens element C 'are used as anti-vibration lens groups. Any one of these anti-vibration lens groups is shifted in a direction perpendicular to the optical axis to prevent a blur of the captured image.

In the optical system S9 according to the ninth example, when the focal length of the entire optical system S9 is f and the image stabilization coefficient at the time of blur correction is K, a lens for blur correction is used to correct the rotational blur at the angle θ. The group may be shifted in a direction orthogonal to the optical axis by (f · tan θ) / K.

The focal lengths f of the entire system in the wide-angle end state, the intermediate focal length state, and the telephoto end state of the optical system S9 according to Example 9 are 18.7 (mm), 70.0 (mm), and 188.0, respectively. mm) (see Table 9 below). The blur correction amount by any of the lens elements A ′, B ′, and C ′ at each focal length and the movement amount of the lens element at that time are as follows, for example.

In the optical system S9 according to Example 9, in the wide-angle end state, the image stabilization coefficient K when correcting the image blur by the lens element A ′ is 0.51, and the focal length is 18.7 (mm). Therefore, the movement amount of the lens element A ′ for correcting the rotational shake of 0.623 ° is 0.400 (mm).

Further, in the intermediate focal length state of the optical system S9 according to the ninth example, the image stabilization coefficient K when correcting the image blur by the lens element B ′ is 0.99, and the focal length is 70.0 ( mm), the moving amount of the lens element B ′ for correcting the rotational blur of 0.321 ° is 0.399 (mm). Here, when the same rotational blur correction is performed by the lens element A ′ in the intermediate focal length state, the image stabilization coefficient K is 0.82 and the focal length is 70.0 (mm). The amount of movement of the lens element A ′ for correcting rotational blur of 0.321 ° is 0.479 (mm). Therefore, if the amount of blur correction is the same, the amount of movement of the image stabilizing lens group is smaller when the correction is performed using the lens element B 'than when the correction is performed using the lens element A'.

In the telephoto end state of the optical system S9 according to the ninth example, the image stabilization coefficient K when correcting the image blur by the lens element C ′ is 2.46, and the focal length is 188.0 (mm). Therefore, the movement amount of the lens element C ′ for correcting the rotational shake of 0.197 ° is 0.400 (mm). Here, when the same rotational blur correction is performed by the lens element A ′ in the telephoto end state, the image stabilization coefficient K is 1.04 and the focal length is 188.0 (mm). The amount of movement of the lens element A ′ for correcting rotational shake of 0.197 ° is 0.951 (mm). Further, when correcting the image blur with the lens element B ′, the image stabilization coefficient K is 1.25, and the focal length is 188.0 (mm), so that the rotation blur of 0.197 ° is corrected. The amount of movement of the lens element B ′ for this purpose is 0.791 (mm). Therefore, if the blur correction amount is the same, the amount of movement of the image stabilizing lens group is smaller when the correction is performed by the lens element C 'than when the correction is performed by the lens element A' or B '.

Thus, since the image stabilization coefficient K increases in the order of the lens element A ′, the lens element B ′, and the lens element C ′, more correction can be performed. That is, if the movement amounts of the lens elements A ′, B ′, and C ′ are the same when the focal length of the entire system is the same, the lens element B ′ can correct a larger amount than the lens element A ′. Further, the lens element C ′ can correct a larger amount than the lens element B ′. In other words, if the amount of blur correction is the same, the lens element B ′ can reduce the amount of movement of the anti-vibration lens group than the lens element A ′, and further the lens element than the lens element B ′. C ′ can reduce the amount of movement of the image stabilizing lens group. Therefore, if the lens element A ′ is driven on the wide-angle end side and controlled so that the lens elements B ′ and C ′ are sequentially driven as the magnification is changed to the telephoto end side, the focal length becomes longer and the blur correction amount increases. Even if the number is increased, more corrections can be made without increasing the amount of movement of the image stabilizing lens group. As a result, from the wide-angle end state to the telephoto end state, the shift amount can be controlled to an appropriate amount without largely shifting the image stabilizing lens group.

In the ninth embodiment, the lens elements A ′ and B ′ are controlled to be changed when the focal length of the entire system reaches one predetermined value, as in the first embodiment. . The change between the lens elements B ′ and C ′ is similarly controlled.

Table 9 below lists specifications of the optical system S9 according to the ninth example of the second embodiment of the present invention.

(Table 9) Ninth embodiment (whole specifications)
W M T
f = 18.7 70.0 188.0
FNO = 3.64 5.44 6.60
TL = 128.6 180.3 216.7
fh = 18.7-68.0
fk = 68.0-110.0
fl = 110.0-188.0

(Surface data)
m r d νd nd
op ∞
1) 128.56287 1.8 37.18 1.834
2) 61.71903 9.4 82.57 1.49782
3) -368.67603 0.12
4) 55.98016 6.8 82.57 1.49782
5) 389.22661 D5
* 6) 43.51896 1.2 47.25 1.77377
7) 11.20367 6.4
8) -27.87211 1.0 40.66 1.88300
9) 45.04115 0.15
10) 26.85149 4.22 23.8 1.84666
11) -30.94189 1.05
12) -19.31231 1.0 46.6 1.80400
13) -58.68682 D13
14> ∞ 1.63 Aperture
15) 31.09309 3.18 82.57 1.49782
16) -66.2335 0.12
17) 24.20499 4.26 82.57 1.49782
18) -22.11253 0.9 25.45 1.80518
19) -90.15429 D19
20) 90.00000 0.8 52.77 1.74100
21) 15.29423 2.5 25.45 1.80518
22) 33.33188 1.4
23) -450.00000 0.8 63.88 1.51680
24) 459.94923 1.2
25) -80.00000 1.2 54.61 1.72916
26) 183.82631 D26
27) 275.95449 4.0 82.47 1.49697
* 28) -21.43596 0.08
29) 55.21481 4.25 70.31 1.48749
30) -30.00000 1.4
31) -15.80000 1.63 37.18 1.83400
32) -31.79204 BF
I ∞

(Aspheric data)
Surface number: 6
κ = -45.4463
A4 = 6.97E-05
A6 = -5.50E-07
A8 = 3.61E−09
A10 = -1.46E-11
A12 = 2.48E-14
Surface number: 28
κ = -5.3904
A4 = -9.11E-05
A6 = 3.36E-07
A8 = −2.85E−09
A10 = 1.17E-11
A12 = −3.50E-14

(Variable interval data)
W M T
D5 1.0 36.0 56.8
D13 23.1 8.3 1.0
D19 0.9 1.1 2.3
D26 2.9 2.3 2.3
BF 38.7 70.6 92.2

(Values for conditional expressions)
fA '=-89.0
fB '=-74.1
fC '=-37.2
fw = 18.7
ft = 188.0
fh = 18.7-69.2
fk = 48.7-122.69
fl = 86.8-188.0
ZSw = 0.204
LSw = −0.400
ZSt = 0.985
LSt = −0.400
LS = −0.400: Image plane correction with lens element A ′ = − 0.400: Image plane correction with lens element B ′ = − 0.400: Image plane correction with lens element C ′ (14) | fC ′ | <| fB ′ | < | FA '|:
37.2 <74.1 <89.0
(15) fw ≦ fh ≦ (| fC ′ | / | fA ′ |) × ft × 0.88:
18.7 ≤ 18.7 to 69.2 ≤ 69.2
(16) (| fC ′ | / | fA ′ |) × ft × 0.62 ≦ fk ≦ (| fC ′ | / | fB ′ |) × ft × 1.30:
48.7 ≤ 48.7 to 122.69 ≤ 122.69
(17) (| fC ′ | / | fB ′ |) × ft × 0.92 ≦ fl ≦ ft:
86.8 ≤ 86.8-188.0 ≤ 188.0
(18) | ZSw | / | LSw | = 0.51
(19) | ZSt | / | LSt | = 2.46
(20) √ (| fA ′ | × fh) /LS=102.0
(21) √ (| fB ′ | × fk) /LS=180.1
(22) √ (| fC ′ | × fl) /LS=209.1

FIGS. 36A and 36B are aberration diagrams in the wide-angle end state of the optical system according to Example 9 at the time of focusing on infinity, FIG. 36A is a diagram of various aberrations, and FIG. 36B is an image blur due to the lens element A ′. It is an aberration diagram when correcting. 37A and 37B are aberration diagrams in the intermediate focal length state when the optical system according to Example 9 is focused at infinity, FIG. 37A is various aberration diagrams, and FIG. 37B is an image by the lens element B ′. FIG. 6 is a diagram showing various aberrations when blur correction is performed. 38A and 38B are aberration diagrams in the telephoto end state of the optical system according to Example 9 at the infinite focus, FIG. 38A is various aberration diagrams, and FIG. 38B is an image blur due to the lens element C ′. It is an aberration diagram when correcting.

As is apparent from each aberration diagram, it can be seen that in the ninth example, various aberrations are well corrected from the wide-angle end state to the telephoto end state, and the imaging performance is excellent.

<Tenth embodiment>
FIG. 39 is a diagram showing a configuration of an optical system S10 according to the tenth example of the second embodiment of the present invention.

As shown in FIG. 39, the optical system S10 according to the tenth example includes a first lens group G1 having a positive refractive power and a second lens group G2 having a negative refractive power in order from an object side (not shown). The aperture stop SP, the third lens group G3 having a positive refractive power, and the fourth lens group G4 having a negative refractive power.

The first lens group G1 includes, in order from the object side, a cemented lens L11 of a negative meniscus lens having a convex surface facing the object side and a biconvex lens, and a positive meniscus lens L12 having a convex surface facing the object side.

The second lens group G2, in order from the object side, has an aspheric shape on the object side, a negative meniscus lens L21 having a convex surface facing the object side, a biconcave lens L22, a biconvex lens L23, and a concave surface on the object side. And a negative meniscus lens L24 directed to it.

The third lens group G3 includes, in order from the object side, a biconvex lens L31, and a cemented lens L32 of a biconvex lens and a negative meniscus lens having a concave surface facing the object side.

The fourth lens group G4 includes, in order from the object side, a cemented lens L41 of a biconcave lens and a positive meniscus lens having a convex surface directed toward the object side, a biconcave lens L42, a biconvex lens L43, and an image surface I side having an aspheric shape. It is composed of a positive meniscus lens L44 having a concave surface facing the object side, a biconvex lens L45, and a negative meniscus lens L46 having a concave surface facing the object side.

On the image plane I, an image sensor (not shown) composed of a CCD, a CMOS, or the like is disposed. The aperture stop SP is disposed between the second lens group G2 and the third lens group G3, and moves together with the third lens group G3 when zooming from the wide-angle end state to the telephoto end state.

In the optical system S10 according to the tenth example, during zooming from the wide-angle end state to the telephoto end state, the first lens group G1, the second lens group G2, the third lens group G3, and the fourth lens group G4 are objects. Move to the side.

In the optical system S10 according to the tenth example, the cemented lens L41 and the biconcave lens L42 in the fourth lens group G4 constitute a lens element B ′, and the refractive power of the lens element B ′ and the lens element B ′. A lens element A ′ is composed of a biconvex lens L43 having refracting powers of different signs, and these lens element A ′ and lens element B ′ are used as anti-vibration lens groups, respectively. By shifting any one of these anti-vibration lens groups in a direction orthogonal to the optical axis, blurring of the captured image is prevented.

In the optical system S10 according to the tenth example, when the focal length of the entire optical system is f and the image stabilization coefficient at the time of blur correction is K, a lens for blur correction is used to correct the rotational blur at the angle θ. The group may be shifted in a direction orthogonal to the optical axis by (f · tan θ) / K.

The focal lengths f of the entire system in the wide-angle end state, the intermediate focal length state, and the telephoto end state of the optical system S10 according to the tenth example are 18.7 (mm), 70.1 (mm), and 188.0, respectively. mm) (see Table 10 below). The blur correction amount by the lens element A ′ or B ′ at each focal length and the movement amount of the lens element at that time are as follows, for example.

In the optical system S10 according to the tenth example, in the wide-angle end state, the image stabilization coefficient K when the image blur is corrected by the lens element A ′ is 0.60, and the focal length is 18.7 (mm). Therefore, the movement amount of the lens element A ′ for correcting the rotation blur of 0.772 ° is 0.421 (mm).

Further, in the intermediate focal length state of the optical system S10 according to the tenth example, the image stabilization coefficient K when the image blur is corrected by the lens element A ′ is 0.94, and the focal length is 70.1 ( mm), the moving amount of the lens element A ′ for correcting the rotational blur of 0.322 ° is 0.421 (mm).

In the telephoto end state of the optical system S10 according to the tenth example, the image stabilization coefficient K for correcting image blur by the lens element B ′ is 2.31, and the focal length is 188.0 (mm). Therefore, the movement amount of the lens element B ′ for correcting the rotational shake of 0.296 ° is 0.421 (mm). Here, when the same rotational blur correction is performed by the lens element A ′ in the telephoto end state, the image stabilization coefficient K is 1.17 and the focal length is 188.0 (mm). The amount of movement of the lens element A ′ for correcting rotational blur of 0.296 ° is 0.834 (mm). Therefore, if the amount of blur correction is the same, the amount of movement of the image stabilizing lens group is smaller when the correction is performed using the lens element B 'than when the correction is performed using the lens element A'.

Thus, in the tenth embodiment, the image stabilization coefficient K increases in the order of the lens element A ′ and the lens element B ′. That is, more correction is possible when the image blur is corrected by the lens element B ′ than by the lens element A ′. If the movement amounts of the lens elements A ′ and B ′ are the same when the focal lengths of the entire system are the same, the lens element B ′ can perform more correction than the lens element A ′. In other words, if the blur correction amount is the same, the lens element B ′ can reduce the movement amount of the image stabilizing lens group compared to the lens element A ′. Therefore, in this embodiment, control is performed so that the lens element A 'is driven at the focal length from the wide-angle end side to the intermediate focal length, and further the lens element B' is driven at the telephoto end side. Then, even if the focal length is increased and the amount of blur correction is increased, more correction can be performed without increasing the amount of movement of the image stabilizing lens group. As a result, from the wide-angle end state to the telephoto end state, the shift amount can be controlled to an appropriate amount without largely shifting the image stabilizing lens group.

Table 10 below lists specifications of the optical system according to Example 10 of the second embodiment of the present invention.

(Table 10) Tenth Example (Overall Specifications)
W M T
f = 18.7 70.1 188.0
FNO = 3.64 5.60 6.97
TL = 130.1 182.0 219.2
fh = 18.7-103.3
fk = 103.3-188.0

(Surface data)
m r d νd nd
op ∞
1) 133.26500 1.4 37.18 1.83400
2) 63.25833 9.2 82.57 1.49782
3) -305.56559 0.12
4) 58.40597 6.4 82.57 1.49782
5) 444.97253 D5
* 6) 45.03974 1.2 47.25 1.77377
7) 11.11015 6.4
8) -24.09331 1.0 40.66 1.88300
9) 68.33997 0.15
10) 31.75544 4.22 23.78 1.84666
11) -28.74651 1.05
12) -17.39728 1.0 46.6 1.80400
13) -38.14366 D13
14> ∞ 1.63 Aperture
15) 26.85327 3.18 82.57 1.49782
16) -48.92537 0.12
17) 28.73946 4.26 82.57 1.49782
18) -24.20835 0.9 25.4 1.80518
19) -150.19371 D19
20) -200.00000 0.8 52.77 1.74100
21) 19.52804 2.5 25.44 1.80518
22) 66.76603 2.0
23) -500.00000 0.8 54.61 1.72916
24) 68.99538 1.2
25) 184.90012 1.9 63.88 1.51680
26) -57.41433 2.3
27) -29.69333 3.0 82.47 1.49697
* 28) -23.59223 0.08
29) 52.67285 4.25 70.31 1.48749
30) -20.13027 1.4
31) -15.95804 1.63 37.18 1.83400
32) -35.63406 BF
I ∞

(Aspheric data)
Surface number: 6
κ = -42.8927
A4 = 6.52E-05
A6 = -4.25E-07
A8 = 2.51E−09
A10 = -9.91E-12
A12 = 1.83E-14
Surface number: 28
κ = -7.2004
A4 = -7.79E-05
A6 = 4.39E-07
A8 = −4.25E−09
A10 = 3.18E-11
A12 = -1.36E-13

(Variable interval data)
W M T
D5 1.0 36.0 56.8
D13 24.8 8.7 1.0
D19 1.5 1.9 3.7
BF 38.7 71.3 93.5

(Values for conditional expressions)
fA '=-82.5
fB '=-40.1
fw = 18.7
ft = 188.0
fh = 18.7-91.38
fk = 91.38-188.0
ZSw = 0.252
LSw = -0.421
ZSt = 0.984
LSt = -0.426
LS = −0.421: Image plane correction with lens element A ′ = − 0.426: Image plane correction with lens element B ′ (7) | fB ′ | <| fA ′ |:
40.1 <82.5
(8) fw ≦ fh ≦ (| fB ′ | / | fA ′ |) × ft × 1.50
18.7 ≤ 18.7 to 91.38 ≤ 91.38
(9) (| fB ′ | / | fA ′ |) × ft × 0.50 ≦ fk ≦ ft:
91.38 ≤ 91.38-188.0 ≤ 188.0
(10) | ZSw | / | LSw | = 0.60
(11) | ZSt | / | LSt | = 2.31
(12) √ (| fA ′ | × fh) /LS=93.297
(13) √ (| fB ′ | × fk) /LS=203.8

40A and 40B are aberration diagrams in the wide-angle end state of the optical system according to Example 10 at the time of focusing on infinity, FIG. 40A is a diagram of various aberrations, and FIG. 40B is an image blur due to the lens element A ′. It is an aberration diagram when correcting. 41A and 41B are aberration diagrams in the intermediate focal length state when the optical system according to Example 10 is focused at infinity, FIG. 41A is various aberration diagrams, and FIG. 41B is an image by the lens element A ′. FIG. 6 is a diagram showing various aberrations when blur correction is performed. 42A and 42B are aberration diagrams in the telephoto end state of the optical system according to the tenth example when focused on infinity, FIG. 42A is various aberration diagrams, and FIG. 42B is an image blur due to the lens element B ′. It is an aberration diagram when correcting.

As is apparent from the respective aberration diagrams, it can be seen that in the tenth embodiment, various aberrations are favorably corrected from the wide-angle end state to the telephoto end state, and the imaging performance is excellent.

<Eleventh embodiment>
FIG. 43 is a diagram showing a configuration of an optical system S11 according to Example 11 of Embodiment 2 of the present invention.

As shown in FIG. 43, the optical system S11 according to the eleventh example includes, in order from the object side (not shown), a first lens group G1 having a positive refractive power, and a second lens group G2 having a negative refractive power. The aperture stop SP, the third lens group G3 having a positive refractive power, the fourth lens group G4 having a negative refractive power, and the fifth lens group G5 having a positive refractive power.

The first lens group G1 includes, in order from the object side, a cemented lens L11 of a negative meniscus lens having a convex surface facing the object side and a positive meniscus lens having a convex surface facing the object side, and a biconvex lens L12.

The second lens group G2, in order from the object side, has an aspheric shape on the object side, a negative meniscus lens L21 having a convex surface facing the object side, a biconcave lens L22, a biconvex lens L23, and a concave surface on the object side. And a negative meniscus lens L24 directed to it.

The third lens group G3 includes, in order from the object side, a biconvex lens L31, and a cemented lens L32 of a biconvex lens and a negative meniscus lens having a concave surface facing the object side.

The fourth lens group G4 includes, in order from the object side, a cemented lens L41 of a negative meniscus lens having a convex surface facing the object side and a positive meniscus lens having a convex surface facing the object side, and a negative meniscus lens having a concave surface facing the object side L42 and a positive meniscus lens L43 having a concave surface facing the object side.

In order from the object side, the fifth lens group G5 has an aspheric shape on the image surface I side, a positive meniscus lens L51 having a concave surface directed to the object side, a biconvex lens L52, and a negative surface having a concave surface directed to the object side. And a meniscus lens L53.

On the image plane I, an image sensor (not shown) composed of a CCD, a CMOS, or the like is disposed. The aperture stop SP is disposed between the second lens group G2 and the third lens group G3, and moves together with the third lens group G3 when zooming from the wide-angle end state to the telephoto end state.

The optical system S11 according to the eleventh example has a first lens group G1, a second lens group G2, a third lens group G3, a fourth lens group G4, a first lens group G1, a zoom lens when zooming from the wide-angle end state to the telephoto end state. The five lens group G5 moves to the object side.

In the optical system S11 according to the eleventh example, the cemented lens L41 and the negative meniscus lens L42 in the fourth lens group G4 constitute a lens element B ′, and the refractive power of the lens element B ′ and the lens element B ′. And a positive meniscus lens L43 having refracting powers of different signs constitute a lens element A ', and these lens element A' and lens element B 'are used as a vibration-proof lens group. By shifting any one of these anti-vibration lens groups in a direction orthogonal to the optical axis, blurring of the captured image is prevented.

In the optical system S11 according to the eleventh example, when the focal length of the entire system is f and the image stabilization coefficient at the time of blur correction is K, in order to correct the rotational blur of the angle θ, the lens group for blur correction is provided. What is necessary is just to shift in the direction orthogonal to the optical axis by (f · tan θ) / K.

The focal lengths f of the entire system in the wide-angle end state, the intermediate focal length state, and the telephoto end state of the optical system S11 according to Example 11 are 18.7 (mm), 70.0 (mm), and 188.0 (respectively). mm) (see Table 11 below). The blur correction amount by the lens element A ′ or B ′ at each focal length and the movement amount of the lens element at that time are as follows, for example.

In the optical system S11 according to the eleventh example, in the wide-angle end state, the image stabilization coefficient K when the image blur is corrected by the lens element A ′ is 0.62, and the focal length is 18.7 (mm). Therefore, the moving amount of the lens element A ′ for correcting the rotation blur of 0.848 ° is 0.446 (mm).

In the intermediate focal length state of the optical system S11 according to the eleventh example, the image stabilization coefficient K when correcting the image blur by the lens element A ′ is 0.99, and the focal length is 70.0 ( mm), the moving amount of the lens element A ′ for correcting the rotational shake of 0.360 ° is 0.446 (mm).

In the telephoto end state of the optical system S11 according to the eleventh example, the image stabilization coefficient K for correcting image blur by the lens element B ′ is 2.21, and the focal length is 188.0 (mm). Therefore, the movement amount of the lens element B ′ for correcting the rotational blur of 0.300 ° is 0.446 (mm). Here, when the same rotational blur correction is performed by the lens element A ′ in the telephoto end state, the image stabilization coefficient K is 1.25 and the focal length is 188.0 (mm). The amount of movement of the lens element A ′ for correcting the rotation blur of 0.300 ° is 0.790 (mm). Therefore, if the amount of blur correction is the same, the amount of movement of the image stabilizing lens group is smaller when the correction is performed using the lens element B 'than when the correction is performed using the lens element A'.

Thus, the image stabilization coefficient K increases in the order of the lens element A ′ and the lens element B ′. That is, more correction is possible when the image blur is corrected by the lens element B ′ than by the lens element A ′. If the movement amounts of the lens elements A ′ and B ′ are the same when the focal lengths of the entire system are the same, the lens element B ′ can perform more correction than the lens element A ′. In other words, if the blur correction amount is the same, the lens element B ′ can reduce the movement amount of the image stabilizing lens group compared to the lens element A ′. Therefore, in this embodiment, control is performed so that the lens element A 'is driven at the focal length from the wide-angle end side to the intermediate focal length, and further the lens element B' is driven at the telephoto end side. Then, even if the focal length is increased and the amount of blur correction is increased, more correction can be performed without increasing the amount of movement of the image stabilizing lens group. As a result, from the wide-angle end state to the telephoto end state, the shift amount can be controlled to an appropriate amount without largely shifting the image stabilizing lens group.

Table 11 below lists specifications of the optical system according to Example 11 of the second embodiment of the present invention.

(Table 11) Eleventh embodiment (whole specifications)
W M T
f = 18.7 70.0 188.0
FNO = 3.55 5.39 6.91
TL = 129.7 182.7 222.5
fh = 18.7-91.38
fk = 91.38-188.0

(Surface data)
m r d νd nd
op ∞
1) 88.3686 1.4 37.18 1.834
2) 51.2341 9.8 82.57 1.49782
3) 588.9823 0.12
4) 65.0932 6.4 82.57 1.49782
5) -3559.6410 D5
* 6) 37.4711 1.2 47.25 1.77377
7) 10.8979 6.4
8) -29.5092 1.0 40.66 1.88300
9) 58.3390 0.15
10) 26.3202 4.22 23.8 1.84666
11) -34.7037 1.05
12) -18.6800 1.0 46.6 1.80400
13) -67.5427 D13
14> ∞ 1.63 Aperture
15) 23.9912 3.18 82.57 1.49782
16) -62.5375 0.12
17) 33.2119 4.26 82.57 1.49782
18) -21.0524 0.9 25.45 1.80518
19) -74.2470 D19
20) 358.8111 0.8 52.77 1.74100
21) 18.2134 2.5 25.45 1.80518
22) 45.8626 2.0
23) -50.0000 0.8 54.61 1.72916
24) -254.5612 1.2
25) -248.3650 1.9 65.44 1.60300
26) -49.5474 2.3
27) -30.0000 4.0 82.47 1.49697
* 28) -20.4714 0.08
29) 43.8397 4.25 70.31 1.48749
30) -31.5343 1.4
31) -16.1983 1.63 37.18 1.83400
32) -30.0990 BF
I ∞

(Aspheric data)
Surface number: 6
κ = -30.2672
A4 = 7.83E-05
A6 = -5.54E-07
A8 = 3.32E−09
A10 = -1.18E-11
A12 = 1.88E-14
Surface number: 28
κ = -4.9613
A4 = -9.15E-05
A6 = 3.67E-07
A8 = -3.27E-09
A10 = 1.76E-11
A12 = -6.39E-14

(Variable interval data)
W M T
D5 1.0 36.0 56.8
D13 23.9 8.3 1.0
D19 0.9 0.9 1.9
D26 1.8 1.8 2.3
BF 38.7 72.4 96.6

(Values for conditional expressions)
fA '=-76.8
fB '=-42.2
fw = 18.7
ft = 188.0
fh = 18.7-103.30
fk = 103.30-188.0
ZSw = 0.279
LSw = -0.45
ZSt = 0.560
LSt = −0.45
LS = −0.45: Image plane correction with lens element A ′ = − 0.45: Image plane correction with lens element B ′ (7) | fB ′ | <| fA ′ |
42.2 <76.8
(8) fw ≦ fh ≦ (| fB ′ | / | fA ′ |) × ft × 1.50
18.7 ≤ 18.7 to 103.30 ≤ 103.30
(9) (| fB ′ | / | fA ′ |) × ft × 0.50 ≦ fk ≦ ft
103.30 ≤ 103.30-188.0 ≤ 188.0
(10) | ZSw | / | LSw | = 0.62
(11) | ZSt | / | LSt | = 1.24
(12) √ (| fA ′ | × fh) /LS=84.2
(13) √ (| fB ′ | × fk) /LS=197.9

44A and 44B are aberration diagrams of the optical system according to Example 11 in the wide-angle end state when focused on infinity, FIG. 44A is a diagram of various aberrations, and FIG. 44B is an image blur due to the lens element A ′. It is an aberration diagram when correcting. 45A and 45B are aberration diagrams in the intermediate focal length state at the time of focusing on infinity of the optical system according to Example 11, FIG. 45A is various aberration diagrams, and FIG. 45B is an image by the lens element A ′. FIG. 6 is a diagram showing various aberrations when blur correction is performed. 46A and 46B are aberration diagrams in the telephoto end state of the optical system according to Example 11 when focused on infinity, FIG. 46A is various aberration diagrams, and FIG. 46B is an image blur due to the lens element B ′. It is an aberration diagram when correcting.

As is apparent from each aberration diagram, it can be seen that in the eleventh example, various aberrations are well corrected from the wide-angle end state to the telephoto end state, and the imaging performance is excellent.

Thus, according to each of the above embodiments, an optical system having a suitable image stabilization function can be realized.

Next, an optical apparatus provided with the optical system according to each embodiment of the present invention will be described.
FIG. 47 is a cross-sectional view schematically showing a digital single-lens reflex camera including the optical system S according to each embodiment of the present invention. In the digital single-lens reflex camera 1 shown in FIG. 47, light from an object (subject) (not shown) is collected by the optical system S and imaged on the focusing plate 5 via the quick return mirror 3. The light imaged on the collecting plate 5 is reflected a plurality of times in the pentaprism 7 and guided to the eyepiece lens 9. Thus, the photographer can observe the object (subject) image as an erect image through the eyepiece 9.

When a release button (not shown) is pressed by the photographer, the quick return mirror 3 is retracted out of the optical path, and the light of the object (subject) collected by the optical system S forms a subject image on the image sensor 11. . Thereby, the light from the object is picked up by the image pickup device 11 and stored in a memory (not shown) as an object image. In this way, the photographer can photograph an object with the camera 1.

With the above configuration, the digital single-lens reflex camera 1 provided with the optical system S according to the present invention has a suitable image stabilization function, can correct various aberrations well, and can realize high optical performance. The camera 1 in FIG. 47 may be one that holds the photographic lens in a detachable manner or may be molded integrally with the photographic lens. The camera may be a single-lens reflex camera or a camera that does not have a quick return mirror or the like.

Here, each example according to each of the above embodiments shows a specific example of the present invention, and the present invention is not limited to these. The contents described below can be appropriately adopted as long as the optical performance is not impaired.

The numerical examples of the optical system according to the present invention are shown as having a four-group or five-group configuration, but the present invention is not limited to this, and an optical system of another group configuration (for example, six groups) can be configured. It is. Specifically, a configuration in which a lens or a lens group is added to the most object side of the optical system of the present invention, or a configuration in which a lens or a lens group is added to the most image side may be used. The lens group indicates a portion having at least one lens separated by an air interval.

In addition, the optical system of the present invention uses a part of a lens group, an entire lens group, or a plurality of lens groups as a focusing lens group to focus on an object from infinity to a close object. It is good also as a structure moved to a direction. The focusing lens group can also be applied to autofocus, and is also suitable for driving by an autofocus motor, such as an ultrasonic motor. In particular, it is preferable that at least a part of the first or second lens group is a focusing lens group.

Further, the lens surface of the lens constituting the optical system of the present invention may be a spherical surface, a flat surface, or an aspheric surface. When the lens surface is a spherical surface or a flat surface, it is preferable because lens processing and assembly adjustment are facilitated, and deterioration of optical performance due to errors in lens processing and assembly adjustment can be prevented. Further, even when the image plane is deviated, it is preferable because there is little deterioration in drawing performance. When the lens surface is aspheric, any of aspherical surfaces by grinding, a glass mold aspherical surface formed by molding glass into an aspherical surface, or a composite aspherical surface formed by forming resin on the glass surface into an aspherical surface An aspherical surface may be used. The lens surface may be a diffractive surface, and the lens may be a gradient index lens (GRIN lens) or a plastic lens.

In addition, the aperture stop SP of the optical system of the present invention is preferably arranged in the vicinity of the anti-vibration lens group, but the role may be substituted by a lens frame without providing a member as the aperture stop.

Further, an antireflection film having a high transmittance in a wide wavelength range may be provided on the lens surface of the lens constituting the optical system of the present invention. Thereby, flare and ghost can be reduced and high contrast optical performance can be achieved.

The optical system of the present invention has a zoom ratio of about 3 to 20 times.

Claims (44)

1. Each having a first lens element and a second lens element that can be shifted to include a component perpendicular to the optical axis;
   The second lens element is composed of the first lens element and another lens element,
   An optical system that performs image plane correction by shifting the first lens element or the second lens element so as to include a component in a direction perpendicular to the optical axis.
2. Each having a first lens element and a second lens element that can be shifted to include a component perpendicular to the optical axis;
   2. The optical system according to claim 1, wherein in the second lens element, the first lens element and the other lens element have the same refractive power.
3. The optical system according to claim 1, wherein a condition of the following formula is satisfied.
   | FB | <| fA |
   However,
   | FA |: absolute value of the focal length of the first lens element | fB |: absolute value of the focal length of the second lens element where fA and fB have the same sign
4. The optical system according to claim 1, wherein a condition of the following formula is satisfied.
   0.24 <| fB | / | fA | <1.00
   However,
   | FA |: absolute value of the focal length of the first lens element | fB |: absolute value of the focal length of the second lens element where fA and fB have the same sign
5. A third lens element that can be shifted so as to include a component in a direction perpendicular to the optical axis is further included, and any one of the first lens element, the second lens element, or the third lens element is 2. The optical system according to claim 1, wherein image plane correction is performed by shifting so as to include a component in a direction perpendicular to the optical axis.
6. 6. The optical system according to claim 5, wherein the third lens element includes the second lens element and another lens element having a refractive power having the same sign as the refractive power of the second lens element. .
7. The optical system according to claim 5, wherein the condition of the following formula is satisfied.
   | FC | <| fB | <| fA |
   However,
   | FA |: absolute value of the focal length of the first lens element | fB |: absolute value of the focal length of the second lens element | fC |: absolute value of the focal length of the third lens element where fA, fB, and fC Is the same sign
8. The optical system according to claim 5, wherein the condition of the following formula is satisfied.
   0.24 <| fC | / | fA | <1.00
   However,
   | FA |: absolute value of the focal length of the first lens element | fC |: absolute value of the focal length of the second lens element where fA and fC have the same sign
9. The optical system according to claim 5, wherein the third lens element includes a cemented lens.
10. The optical system according to claim 1, wherein the first and second lens elements have cemented lenses.
11. 2. The optical system according to claim 1, further comprising at least four lens groups, wherein at least the first and second lens elements are included in any one of the four lens groups.
12. In order from the object side, the zoom lens has a first lens group, a second lens group, a third lens group, and a fourth lens group, and at the time of zooming, the distance between the first lens group and the second lens group, The optical system according to claim 11, wherein an interval between the second lens group and the third lens group and an interval between the third lens group and the fourth lens group are changed.
13. Each having a first lens element and a second lens element that can be shifted to include a component perpendicular to the optical axis;
    2. The optical system according to claim 1, wherein in the second lens element, the first lens element and the other lens element have different signs of refractive power.
14. The optical system according to claim 1, wherein a condition of the following formula is satisfied.
    | FA | <| fB |
    However,
    | FA |: Absolute value of the focal length of the first lens element | fB |: Absolute value of the focal length of the second lens element However, fA and fB have different signs
15. The optical system according to claim 1, wherein a condition of the following formula is satisfied.
    0.24 <| fA | / | fB | <1.00
    However,
    | FA |: Absolute value of the focal length of the first lens element | fB |: Absolute value of the focal length of the second lens element However, fA and fB have different signs
16. An imaging apparatus comprising the optical system according to claim 1.
17. Each having a first lens element and a second lens element that can be shifted to include a component perpendicular to the optical axis;
    Upon zooming from the wide-angle end state to the telephoto end state, either the first lens element or the second lens element is used as the optical axis in accordance with a change in focal length from the wide-angle end state to the telephoto end state. An optical system characterized in that image plane correction is performed by shifting so as to include a component in the vertical direction, and the condition of the following equation is satisfied.
    | FB '| <| fA' |
    fw ≦ fh ≦ (| fB ′ | / | fA ′ |) × ft × 1.50
    (| FB ′ | / | fA ′ |) × ft × 0.50 ≦ fk ≦ ft
    However,
    fA ′: focal length of the first lens element fB ′: focal length of the second lens element fw: focal length of the entire optical system in the wide-angle end state ft: focal length of the entire optical system in the telephoto end state fh: Focal length of the entire optical system when image plane correction is performed by the first lens element fk: Focal length of the entire optical system when image plane correction is performed by the second lens element
18. The optical system according to claim 17, wherein the following condition is satisfied.
    0.40 <| ZSw | / | LSw | <1.50
    However,
    Zsw: the amount of movement of the image on the image plane in the wide-angle end state Lsw: the amount of shift of the lens element that performs image plane correction in the wide-angle end state
19. The optical system according to claim 17, wherein the following condition is satisfied.
    1.00 <| ZSt | / | LSt | <2.70
    However,
    ZSt: Amount of image movement on the imaging surface in the telephoto end state LSt: A shift amount of the lens element that performs image plane correction in the telephoto end state
20. The optical system according to claim 17, wherein the following condition is satisfied.
    80.0 <√ (| fA ′ | × fh) / LS <230.0
    80.0 <√ (| fB ′ | × fk) / LS <230.0
    However,
    fA ′: focal length of the first lens element fB ′: focal length of the second lens element fh: focal length of the entire optical system when image plane correction is performed by the first lens element fk: image plane by the second lens element Focal length of entire optical system when performing correction LS: Shift amount of lens element that performs image plane correction when performing image plane correction
21. The optical system according to any one of claims 1 to 4, wherein the first lens element and the second lens element include a cemented lens.
22. Each having a first lens element, a second lens element, and a third lens element that can be shifted so as to include a component perpendicular to the optical axis;
    Upon zooming from the wide-angle end state to the telephoto end state, the first lens element, the second lens element, or the third lens element is changed according to a change in focal length from the wide-angle end state to the telephoto end state. An optical system that performs image plane correction by shifting any one of them so as to include a component in a direction perpendicular to the optical axis.
23. The optical system according to claim 22, wherein the condition of the following formula is satisfied.
    | FC ′ | <| fB ′ | <| fA ′ |
    However,
    fA ′: focal length of the first lens element fB ′: focal length of the second lens element fC ′: focal length of the third lens element
24. The optical system according to claim 22, wherein the condition of the following formula is satisfied.
    fw ≦ fh ≦ (| fC ′ | / | fA ′ |) × ft × 0.88
    However,
    fA ′: focal length of the first lens element fC ′: focal length of the third lens element fw: focal length of the entire optical system at the wide angle end ft: focal length of the entire optical system at the telephoto end fh: first Focal length of the entire optical system when correcting the image plane with a lens element
25. The optical system according to claim 22, wherein the condition of the following formula is satisfied.
    (| FC ′ | / | fA ′ |) × ft × 0.62 ≦ fk ≦ (| fC ′ | / | fB ′ |) × ft × 1.30
    However,
    fA ′: focal length of the first lens element fB ′: focal length of the second lens element fC ′: focal length of the third lens element ft: focal length of the entire optical system at the telephoto end fk: second lens element Focal length of the entire optical system when performing image plane correction
26. The optical system according to claim 22, wherein the condition of the following formula is satisfied.
    (| FC ′ | / | fB ′ |) × ft × 0.92 ≦ fl ≦ ft
    However,
    fB ′: focal length of the second lens element fC ′: focal length of the third lens element ft: focal length of the entire optical system at the telephoto end fl: total optical system when image plane correction is performed by the third lens element System focal length
27. The optical system according to claim 22, wherein the condition of the following formula is satisfied.
    | FC ′ | <| fB ′ | <| fA ′ |
    fw ≦ fh ≦ (| fC ′ | / | fA ′ |) × ft × 0.88
    (| FC ′ | / | fA ′ |) × ft × 0.62 ≦ fk ≦ (| fC ′ | / | fB ′ |) × ft × 1.30
    (| FC ′ | / | fB ′ |) × ft × 0.92 ≦ fl ≦ ft
    However,
    fA ′: focal length of the first lens element fB ′: focal length of the second lens element fC ′: focal length of the third lens element fw: focal length of the entire optical system at the wide-angle end ft: optics at the telephoto end Focal length of the entire system fh: Focal length of the entire optical system when image plane correction is performed by the first lens element fk: Focal length of the entire optical system when image plane correction is performed by the second lens element fl: Focal length of the entire optical system when image plane correction is performed with the third lens element
28. The optical system according to claim 22, wherein the following condition is satisfied.
    0.40 <| ZSw | / | LSw | <1.40
    However,
    Zsw: amount of movement of the image on the image plane at the wide-angle end Lsw: shift amount of the lens element that performs image plane correction at the wide-angle end
29. The optical system according to claim 22, wherein the following condition is satisfied.
    1.10 <| ZSt | / | LSt | <2.60
    However,
    ZSt: Amount of image movement on the imaging surface at the telephoto end LSt: A shift amount of the lens element that performs image plane correction at the telephoto end
30. The optical system according to claim 22, wherein the following condition is satisfied.
    90.0 <√ (| fA ′ | × fh) / LS <230.0
    90.0 <√ (| fB ′ | × fk) / LS <230.0
    90.0 <√ (| fC ′ | × fl) / LS <230.0
    However,
    fA ′: focal length of the first lens element that performs image plane correction fB ′: focal length of the second lens element that performs image plane correction fC ′: focal length of the third lens element that performs image plane correction fh: first lens Focal length of the entire optical system when performing image surface correction with an element fk: Focal length of the entire optical system when performing image surface correction with a second lens element fl: When performing image surface correction with a third lens element Focal length of the entire optical system LS: shift amount of the lens element that performs the image plane correction when the image plane correction is performed
31. 23. The optical system according to claim 22, wherein the first, second and third lens elements have cemented lenses.
32. An imaging apparatus comprising the optical system according to claim 17.
33. An image pickup apparatus comprising the optical system according to claim 22.
34. A method of manufacturing an optical system having a first lens element and a second lens element,
    The second lens element is composed of the first lens element and another lens element,
    The first lens element and the second lens element are each arranged so as to be shiftable so as to include a component perpendicular to the optical axis,
    The image plane correction is performed by shifting either the first lens element or the second lens element so as to include a component in a direction perpendicular to the optical axis. Method.
35. Each having a first lens element and a second lens element that can be shifted to include a component perpendicular to the optical axis;
    35. The method of manufacturing an optical system according to claim 34, wherein, in the second lens element, the first lens element and the other lens element have the same refractive power.
36. 35. The method of manufacturing an optical system according to claim 34, wherein the condition of the following formula is satisfied.
    | FB | <| fA |
    However,
    | FA |: absolute value of the focal length of the first lens element | fB |: absolute value of the focal length of the second lens element where fA and fB have the same sign
37. A third lens element that can be shifted to include a component in a direction perpendicular to the optical axis is further included, and any one of the first lens element, the second lens element, or the third lens element is 35. The method of manufacturing an optical system according to 34, wherein image plane correction is performed by shifting so as to include a component in a direction perpendicular to the optical axis.
38. Each having a first lens element and a second lens element that can be shifted to include a component perpendicular to the optical axis;
    35. The method of manufacturing an optical system according to claim 34, wherein, in the second lens element, the first lens element and the other lens element have different signs of refractive power.
39. 35. The method of manufacturing an optical system according to claim 34, wherein the condition of the following formula is satisfied.
    | FA | <| fB |
    However,
    | FA |: Absolute value of focal length of first lens element | fB |: Absolute value of focal length of second lens element However, fA and fB have different signs
40. A method of manufacturing an optical system having a first lens element and a second lens element,
    The first lens element and the second lens element are configured to be shiftable so as to include a component perpendicular to the optical axis,
    Upon zooming from the wide-angle end state to the telephoto end state, either the first lens element or the second lens element is used as the optical axis in accordance with a change in focal length from the wide-angle end state to the telephoto end state. Is configured to perform image plane correction by shifting so as to include a vertical component.
    A method for producing an optical system, characterized by satisfying the condition of the following formula:
    | FB '| <| fA' |
    fw ≦ fh ≦ (| fB ′ | / | fA ′ |) × ft × 1.50
    (| FB ′ | / | fA ′ |) × ft × 0.50 ≦ fk ≦ ft
    However,
    fA ′: focal length of the first lens element fB ′: focal length of the second lens element fw: focal length of the entire optical system in the wide-angle end state ft: focal length of the entire optical system in the telephoto end state fh: Focal length of the entire optical system when image plane correction is performed by the first lens element fk: Focal length of the entire optical system when image plane correction is performed by the second lens element
41. The method for manufacturing an optical system according to claim 40, wherein the following condition is satisfied.
    0.40 <| ZSw | / | LSw | <1.50
    However,
    Zsw: the amount of movement of the image on the image plane in the wide-angle end state Lsw: the amount of shift of the lens element that performs image plane correction in the wide-angle end state
42. The method for manufacturing an optical system according to claim 40, wherein the following condition is satisfied.
    1.00 <| ZSt | / | LSt | <2.70
    However,
    ZSt: Amount of image movement on the imaging surface in the telephoto end state LSt: A shift amount of the lens element that performs image plane correction in the telephoto end state
43. A method of manufacturing an optical system having a first lens element, a second lens element, and a third lens element,
    The first lens element, the second lens element, and the third lens element are configured to be shiftable so as to include a component in a direction perpendicular to the optical axis,
    Upon zooming from the wide-angle end state to the telephoto end state, the first lens element, the second lens element, or the third lens element is changed according to a change in focal length from the wide-angle end state to the telephoto end state. A method of manufacturing an optical system, characterized in that any one of them is configured to perform image plane correction by shifting so as to include a component in a direction perpendicular to the optical axis.
44. 44. The method of manufacturing an optical system according to claim 43, wherein the condition of the following formula is satisfied.
    | FC ′ | <| fB ′ | <| fA ′ |
    However,
    fA ′: focal length of the first lens element fB ′: focal length of the second lens element fC ′: focal length of the third lens element

Images