Variable magnification optical system, interchangeable lens, and imaging device

Abstract

To provide a zoom optical system which offers good optical performance by providing appropriate arrangement of multiple focusing lens groups within the optical system and appropriate distribution of refractive power, and to provide an interchangeable lens and an image capturing device.SOLUTION: A zoom optical system is provided, comprising an object-side lens group, an aperture stop, and an image-side lens group. The object-side lens group comprises an object-side first lens group and an object-side second lens group. The image-side lens group comprises an image-side first lens group having positive refractive power, an image-side intermediate lens group, and an image-side final lens group. At least a portion of the object-side second lens group has an object-side focusing lens group configured to move along an optical axis while shifting focus from infinity to a short distance. At least a portion of the image-side intermediate lens group has an image-side focusing lens group configured to move along the optical axis while shifting focus from infinity to a short distance. The object-side focusing lens group and the image-side focusing lens group move along the optical axis on different trajectories while shifting focus from infinity to a short distance.SELECTED DRAWING: Figure 1

Claims

1. The optical system is composed of, in order from the object side, an object-side lens group, an aperture stop, and an image-side lens group, the object-side lens group includes, in order from the object side, a first object-side lens group and a second object-side lens group; the image-side lens group is composed of, in order from the object side, an image-side first lens group having a positive refractive power, an image-side intermediate lens group, and an image-side final lens group; When changing magnification from the short focal length end to the long focal length end, the spacing between adjacent lens groups changes. At least a part of the object-side second lens group includes an object-side focusing lens group that moves in the optical axis direction during focusing from infinity to a close distance, At least a part of the image-side intermediate lens group has an image-side focusing lens group that moves in the optical axis direction during focusing from infinity to a close distance, The object-side focusing lens group and the image-side focusing lens group move along different paths in the optical axis direction when focusing from infinity to a close distance, When the object-side focusing lens group is the first focusing lens group and the image-side focusing lens group is the second focusing lens group, the following conditional expressions (1) and (2) are satisfied: A variable magnification optical system characterized by: (1) 1.170≦|f1 / f2|<10 (2) 3.0<|p2T / p1T|<20 however, f1: focal length of the first focusing lens group, f2: focal length of the second focusing lens group, p1T: focus sensitivity of the first focusing lens group when focusing on infinity at the long focal length end, p2T: focus sensitivity of the second focusing lens group when focusing on infinity at the long focal length end, p1T=(1-m1T^2)×m1RT^2 p2T=(1-m2T^2)×m2RT^2 m1T: paraxial lateral magnification of the first focusing lens group when focusing on infinity at the long focal length end, m1RT: paraxial lateral magnification of the optical system on the image side of the first focusing lens group when focusing on infinity at the long focal length end, m2T: paraxial lateral magnification of the second focusing lens group when focusing on infinity at the long focal length end, m2RT: the paraxial lateral magnification of the optical system on the image side of the second focusing lens group when focusing on infinity at the long focal length end.

2. The following condition (3) is satisfied:

2. The variable magnification optical system according to claim 1. (3) 0.10<|p2W / p2T|<10 however, p2W: focus sensitivity of the second focusing lens group when focusing on infinity at the short focal length end, p2T: focus sensitivity of the second focusing lens group when focusing on infinity at the long focal length end, p2W=(1-m2W^2)×m2RW^2 p2T=(1-m2T^2)×m2RT^2 m2W: paraxial lateral magnification of the second focusing lens group when focusing on infinity at the short focal length end, m2RW: paraxial lateral magnification of the optical system on the image side of the second focusing lens group when focusing on infinity at the short focal length end, m2T: paraxial lateral magnification of the second focusing lens group when focusing on infinity at the long focal length end, m2RT: the paraxial lateral magnification of the optical system on the image side of the second focusing lens group when focusing on infinity at the long focal length end.

3. The following condition (4) is satisfied:

3. A variable magnification optical system according to claim 1 or 2. (4) 0.05<|p1W / p1T|<5.0 however, p1W: focus sensitivity of the first focusing lens group when focusing on infinity at the short focal length end, p1T: focus sensitivity of the first focusing lens group when focusing on infinity at the long focal length end, p1W=(1-m1W^2)×m1RW^2 p1T=(1-m1T^2)×m1RT^2 m1W: paraxial lateral magnification of the first focusing lens group when focusing on infinity at the short focal length extremity, m1RW: paraxial lateral magnification of the optical system on the image side of the first focusing lens group when focusing on infinity at the short focal length end, m1T: paraxial lateral magnification of the first focusing lens group when focusing on infinity at the long focal length end, m1RT: the paraxial lateral magnification of the optical system on the image side of the first focusing lens group when focusing on infinity at the long focal length end.

4. The following condition (5) is satisfied:

4. The variable magnification optical system according to claim 1, wherein the first lens is a lens having a first focal length of 100 mm or less. (5) 1.5<|p2W / p1W|<15 however, p1W: focus sensitivity of the first focusing lens group when focusing on infinity at the short focal length end, p2W: focus sensitivity of the second focusing lens group when focusing on infinity at the short focal length end, p1W=(1-m1W^2)×m1RW^2 p2W=(1-m2W^2)×m2RW^2 m1W: paraxial lateral magnification of the first focusing lens group when focusing on infinity at the short focal length extremity, m1RW: paraxial lateral magnification of the optical system on the image side of the first focusing lens group when focusing on infinity at the short focal length end, m2W: paraxial lateral magnification of the second focusing lens group when focusing on infinity at the short focal length end, m2RW: the paraxial lateral magnification of the optical system on the image side of the second focusing lens group when focused on infinity at the short focal length extremity.

5. The following conditional expressions (6) and (7) are satisfied:

5. A variable magnification optical system according to claim 1, wherein the first lens is a lens having a first focal length of 100 mm or less. (6) 1.3<d1W / d2W<2.0 (7) 0.015<d1T / d2T<0.15 however, d1W: the length from the aperture stop to the optical surface of the first focusing lens group closest to the aperture stop at the short focal length end, d2W: the length from the aperture stop to the optical surface of the second focusing lens group closest to the aperture stop at the short focal length end, d1T: the length from the aperture stop to the optical surface of the first focusing lens group closest to the aperture stop at the long focal length end, d2T: the length from the aperture stop to the optical surface of the second focusing lens group that is closest to the aperture stop at the long focal length extremity.

6. The optical system is composed of, in order from the object side, an object-side lens group, an aperture stop, and an image-side lens group, the object-side lens group includes, in order from the object side, a first object-side lens group and a second object-side lens group; the image-side lens group is composed of, in order from the object side, an image-side first lens group having a positive refractive power, an image-side intermediate lens group, and an image-side final lens group; When changing magnification from the short focal length end to the long focal length end, the spacing between adjacent lens groups changes. At least a part of the object-side second lens group includes an object-side focusing lens group that moves in the optical axis direction during focusing from infinity to a close distance, At least a part of the image-side intermediate lens group has an image-side focusing lens group that moves in the optical axis direction during focusing from infinity to a close distance, The object-side focusing lens group and the image-side focusing lens group move along different paths in the optical axis direction when focusing from infinity to a close distance, When the object-side focusing lens group is the first focusing lens group and the image-side focusing lens group is the second focusing lens group, the following conditional expressions (1') and (2') are satisfied: A variable magnification optical system characterized by: (1') 1.0<|f1 / f2|<10 (2') 0.03<|p2T / p1T|≦0.250 however, f1: focal length of the first focusing lens group, f2: focal length of the second focusing lens group, p1T: focus sensitivity of the first focusing lens group when focusing on infinity at the long focal length end, p2T: focus sensitivity of the second focusing lens group when focusing on infinity at the long focal length end, p1T=(1-m1T^2)×m1RT^2 p2T=(1-m2T^2)×m2RT^2 m1T: paraxial lateral magnification of the first focusing lens group when focusing on infinity at the long focal length end, m1RT: paraxial lateral magnification of the optical system on the image side of the first focusing lens group when focusing on infinity at the long focal length end, m2T: paraxial lateral magnification of the second focusing lens group when focusing on infinity at the long focal length end, m2RT: the paraxial lateral magnification of the optical system on the image side of the second focusing lens group when focusing on infinity at the long focal length end.

7. The following condition (3') is satisfied:

7. The variable magnification optical system according to claim 6. (3') 1.0<|p2W / p2T|<10 however, p2W: focus sensitivity of the second focusing lens group when focusing on infinity at the short focal length end, p2T: focus sensitivity of the second focusing lens group when focusing on infinity at the long focal length end, p2W=(1-m2W^2)×m2RW^2 p2T=(1-m2T^2)×m2RT^2 m2W: paraxial lateral magnification of the second focusing lens group when focusing on infinity at the short focal length end, m2RW: paraxial lateral magnification of the optical system on the image side of the second focusing lens group when focusing on infinity at the short focal length end, m2T: paraxial lateral magnification of the second focusing lens group when focusing on infinity at the long focal length end, m2RT: the paraxial lateral magnification of the optical system on the image side of the second focusing lens group when focusing on infinity at the long focal length end.

8. The following condition (4') is satisfied:

8. The variable magnification optical system according to claim 6 or 7. (4') 0.0015<|p1W / p1T|<0.15 however, p1W: focus sensitivity of the first focusing lens group when focusing on infinity at the short focal length end, p1T: focus sensitivity of the first focusing lens group when focusing on infinity at the long focal length end, p1W=(1-m1W^2)×m1RW^2 p1T=(1-m1T^2)×m1RT^2 m1W: paraxial lateral magnification of the first focusing lens group when focusing on infinity at the short focal length extremity, m1RW: paraxial lateral magnification of the optical system on the image side of the first focusing lens group when focusing on infinity at the short focal length end, m1T: paraxial lateral magnification of the first focusing lens group when focusing on infinity at the long focal length end, m1RT: the paraxial lateral magnification of the optical system on the image side of the first focusing lens group when focusing on infinity at the long focal length end.

9. The following condition (5') is satisfied:

9. The variable magnification optical system according to claim 6, wherein the first lens is a lens having a first focal length of 100 nm or less. (5')1.5<|p2W / p1W|<15 however, p1W: focus sensitivity of the first focusing lens group when focusing on infinity at the short focal length end, p2W: focus sensitivity of the second focusing lens group when focusing on infinity at the short focal length end, p1W=(1-m1W^2)×m1RW^2 p2W=(1-m2W^2)×m2RW^2 m1W: paraxial lateral magnification of the first focusing lens group when focusing on infinity at the short focal length extremity, m1RW: paraxial lateral magnification of the optical system on the image side of the first focusing lens group when focusing on infinity at the short focal length end, m2W: paraxial lateral magnification of the second focusing lens group when focusing on infinity at the short focal length end, m2RW: the paraxial lateral magnification of the optical system on the image side of the second focusing lens group when focused on infinity at the short focal length extremity.

10. The following conditional expressions (6') and (7') are satisfied:

10. The variable magnification optical system according to claim 6, (6') 1.3<d1W / d2W<2.0 (7') 0.015<d1T / d2T<0.15 however, d1W: the length from the aperture stop to the optical surface of the first focusing lens group closest to the aperture stop at the short focal length end, d2W: the length from the aperture stop to the optical surface of the second focusing lens group closest to the aperture stop at the short focal length end, d1T: the length from the aperture stop to the optical surface of the first focusing lens group closest to the aperture stop at the long focal length end, d2T: the length from the aperture stop to the optical surface of the second focusing lens group that is closest to the aperture stop at the long focal length extremity.

11. The optical system is composed of, in order from the object side, an object-side lens group, an aperture stop, and an image-side lens group, the object-side lens group includes, in order from the object side, a first object-side lens group and a second object-side lens group; the image-side lens group is composed of, in order from the object side, an image-side first lens group having a positive refractive power, an image-side intermediate lens group, and an image-side final lens group; When changing magnification from the short focal length end to the long focal length end, the spacing between adjacent lens groups changes. At least a part of the object-side second lens group includes an object-side focusing lens group that moves in the optical axis direction during focusing from infinity to a close distance, At least a part of the image-side intermediate lens group has an image-side focusing lens group that moves in the optical axis direction during focusing from infinity to a close distance, The object-side focusing lens group and the image-side focusing lens group move along different paths in the optical axis direction when focusing from infinity to a close distance, When one of the object-side focusing lens group and the image-side focusing lens group, which has a larger absolute value of refractive power, is designated as the first focusing lens group, and the other of the image-side focusing lens group, which has a smaller absolute value of refractive power, is designated as the second focusing lens group, the following conditional expressions (1A) and (2A) are satisfied: A variable magnification optical system characterized by: (1A) 0.618≦|f1 / f2|<1 (2A) 4.072≦|p2T / p1T|<30 however, f1: focal length of the first focusing lens group, f2: focal length of the second focusing lens group, p1T: focus sensitivity of the first focusing lens group when focusing on infinity at the long focal length end, p2T: focus sensitivity of the second focusing lens group when focusing on infinity at the long focal length end, p1T=(1-m1T^2)×m1RT^2 p2T=(1-m2T^2)×m2RT^2 m1T: paraxial lateral magnification of the first focusing lens group when focusing on infinity at the long focal length end, m1RT: paraxial lateral magnification of the optical system on the image side of the first focusing lens group when focusing on infinity at the long focal length end, m2T: paraxial lateral magnification of the second focusing lens group when focusing on infinity at the long focal length end, m2RT: the paraxial lateral magnification of the optical system on the image side of the second focusing lens group when focusing on infinity at the long focal length end.

12. The following condition (3A) is satisfied:

12. The variable magnification optical system according to claim 11. (3A) 0.02<|p2W / p2T|<2.0 however, p2W: focus sensitivity of the second focusing lens group when focusing on infinity at the short focal length end, p2T: focus sensitivity of the second focusing lens group when focusing on infinity at the long focal length end, p2W=(1-m2W^2)×m2RW^2 p2T=(1-m2T^2)×m2RT^2 m2W: paraxial lateral magnification of the second focusing lens group when focusing on infinity at the short focal length end, m2RW: paraxial lateral magnification of the optical system on the image side of the second focusing lens group when focusing on infinity at the short focal length end, m2T: paraxial lateral magnification of the second focusing lens group when focusing on infinity at the long focal length end, m2RT: the paraxial lateral magnification of the optical system on the image side of the second focusing lens group when focusing on infinity at the long focal length end.

13. The following condition (4A) is satisfied:

13. The variable magnification optical system according to claim 11 or 12. (4A) 0.7<|p1W / p1T|<7.0 however, p1W: focus sensitivity of the first focusing lens group when focusing on infinity at the short focal length end, p1T: focus sensitivity of the first focusing lens group when focusing on infinity at the long focal length end, p1W=(1-m1W^2)×m1RW^2 p1T=(1-m1T^2)×m1RT^2 m1W: paraxial lateral magnification of the first focusing lens group when focusing on infinity at the short focal length extremity, m1RW: paraxial lateral magnification of the optical system on the image side of the first focusing lens group when focusing on infinity at the short focal length end, m1T: paraxial lateral magnification of the first focusing lens group when focusing on infinity at the long focal length end, m1RT: the paraxial lateral magnification of the optical system on the image side of the first focusing lens group when focusing on infinity at the long focal length end.

14. The following condition (5A) is satisfied:

14. The variable magnification optical system according to claim 11, (5A) 0.1<|p2W / p1W|<10 however, p1W: focus sensitivity of the first focusing lens group when focusing on infinity at the short focal length end, p2W: focus sensitivity of the second focusing lens group when focusing on infinity at the short focal length end, p1W=(1-m1W^2)×m1RW^2 p2W=(1-m2W^2)×m2RW^2 m1W: paraxial lateral magnification of the first focusing lens group when focusing on infinity at the short focal length extremity, m1RW: paraxial lateral magnification of the optical system on the image side of the first focusing lens group when focusing on infinity at the short focal length end, m2W: paraxial lateral magnification of the second focusing lens group when focusing on infinity at the short focal length end, m2RW: the paraxial lateral magnification of the optical system on the image side of the second focusing lens group when focused on infinity at the short focal length extremity.

15. The following conditional expressions (6A) and (7A) are satisfied:

15. A variable magnification optical system according to claim 11. (6A) 0.6<d1W / d2W<1.0 (7A) 3.0<d1T / d2T<30 however, d1W: the length from the aperture stop to the optical surface of the first focusing lens group closest to the aperture stop at the short focal length end, d2W: the length from the aperture stop to the optical surface of the second focusing lens group closest to the aperture stop at the short focal length end, d1T: the length from the aperture stop to the optical surface of the first focusing lens group closest to the aperture stop at the long focal length end, d2T: the length from the aperture stop to the optical surface of the second focusing lens group that is closest to the aperture stop at the long focal length extremity.

16. 16. An interchangeable lens comprising the variable magnification optical system according to claim 1.

17. 16. An image pickup apparatus comprising the variable magnification optical system according to claim 1.

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