Zoom optical system, optical device and method for manufacturing the zoom optical system
A first lens group (G 1 ) having positive refractive power, a front-side lens group (GX), an intermediate lens group (GM) having positive refractive power, and a rear-side lens group (GR) are arranged in order from an object side. The front-side lens group (GX) is composed of one or more lens groups and has a negative lens group At least part of the intermediate lens group (GM) is a focusing lens group (GF). The rear-side lens group (GR) is composed of one or more lens groups. Upon zooming, the first lens group (G 1 ) is moved with respect to an image surface, a distance between the first lens group (G 1 ) and the front-side lens group (GX) is changed, a distance between the front-side lens group (GX) and the intermediate lens group (GM) is changed, and a distance between the intermediate lens group (GM) and the rear-side lens group (GR) is changed.
1. A zoom optical system comprising, in order from an object side:
a first lens group having positive refractive power;
a front-side lens group;
an intermediate lens group having positive refractive power; and
a rear-side lens group,
wherein the front-side lens group is composed of one or more lens groups and has a negative lens group,
at least part of the intermediate lens group is a focusing lens group,
the rear-side lens group is composed of one or more lens groups,
upon zooming, the first lens group and the intermediate lens group are moved with respect to an image surface, a distance between the first lens group and the front-side lens group is changed, and a distance between the intermediate lens group and the rear-side lens group is changed, and
the following conditional expressions are satisfied:
0.430<| fF/fRF|< 10.000
0.420<(− fXn )/ fXR< 2.000
0.010< fF/fW< 8.000
32.000≤ Wω
where fF denotes a focal length of the focusing lens group,
fRF denotes a focal length of a lens group closest to the object side in the rear-side lens group,
fXn denotes a focal length of a lens group with a largest absolute value of refractive power in a negative lens group of the front-side lens group,
fXR denotes a focal length of a lens group closest to the image surface in the front-side lens group,
fW denotes a focal length of the zoom optical system in a wide-angle end state, and
Wω denotes a half angle of view in the wide-angle end state.
2. The zoom optical system according to claim 1 , wherein
the rear-side lens group is composed of two or more lens groups,
upon zooming from the wide-angle end state to a telephoto end state, the intermediate lens group moves toward the object side, and a distance between the intermediate lens group and the rear-side lens group increases, and
the following conditional expressions are satisfied:
0.010<( DMRT−DMRW )/ fF< 1.000
Tω≤ 20.000
where DMRW denotes a distance between the intermediate lens group and a lens group closest to the object side in the rear-side lens group in the wide-angle end state,
DMRT denotes a distance between the intermediate lens group and the lens group closest to the object side in the rear-side lens group in the telephoto end state, and
Tω denotes a half angle of view in the telephoto end state.
3. The zoom optical system according to claim 1 , wherein the following conditional expressions are satisfied:
0.001< DXRFT/fF< 1.500
Tω≤ 20.000
0.100< DGXR/fXR< 1.500
where DXRFT denotes a distance between a lens group closest to the image surface in the front-side lens group and the focusing lens group in a telephoto end state,
Tω denotes a half angle of view in the telephoto end state, and
DGXR denotes a thickness, on an optical axis, of a lens group closest to the image surface in the front-side lens group.
4. The zoom optical system according to claim 1 , wherein the following conditional expressions are satisfied:
0.010< fF/fXR< 10.000
0.100< DGXR/fXR< 1.500
fRF2 denotes a focal length of a lens group second closest to the object side in the rear-side lens group,
where DGXR denotes a thickness, on optical axis, of a lens group closest to the image surface in the front-side lens groups.
5. The zoom optical system according to claim 1 , wherein upon zooming from the wide-angle end state to a telephoto end state, the distance between the lens group closest to the image surface in the front-side lens group and the intermediate lens group increases when approaching an intermediate focal length state from the wide-angle end state and decreases when approaching the telephoto end state from the intermediate focal length state.
6. The zoom optical system according to claim 1 , wherein the following conditional expressions are satisfied:
−10.000< fRF/fRF 2<10.000
0.100< DGXR/fXR< 1.500
where fRF2 denotes a focal length of a lens group second closest to the object side in the rear-side lens group, and
DGXR denotes a thickness, on an optical axis, of a lens group closest to the image surface in the front-side lens group.
7. The zoom optical system according to claim 1 , wherein the following conditional expressions are satisfied:
0.420<(− fXn )/ fXR< 1.000
0.100 <DGXR/fXR< 1.500
where DGXR denotes a thickness, on an optical axis, of a lens group closest to the image surface in the front-side lens group.
8. The zoom optical system according to claim 1 , wherein the following conditional expression is satisfied:
0.390< DXnW/ZD 1<5.000
where DXnW denotes a distance between a lens group with a largest absolute value of refractive power in negative lens groups of the front-side lens group in the wide-angle end state and a lens group closest to the image surface in the front-side lens group, and
ZD1 denotes a movement amount of the first lens group upon zooming from the wide-angle end state to the telephoto end state.
9. The zoom optical system according to claim 1 , wherein
an air lens having a meniscus shape is formed by a lens surface on the image surface side of a lens closest to the image surface among lenses disposed to the object side of the focusing lens group and a lens surface closest to the object side in the focusing lens group, and
the following conditional expression is satisfied:
−0.400<β Ft< 0.400
where βFt denotes a lateral magnification of the focusing lens group in a telephoto end state.
10. The zoom optical system according to claim 1 , wherein the following conditional expression is satisfied:
1.250<( rB+rA )/( rB−rA )<10.000
where rA denotes a radius of curvature of a lens surface facing a lens surface closest to the object side in the focusing lens group with a distance in between, and
rB denotes a radius of curvature of the lens surface closest to the object side in the focusing lens group.
11. The zoom optical system according to claim 1 , wherein the focusing lens group includes a negative lens having a meniscus shape with a concave surface facing the object side.
12. The zoom optical system according to claim 1 , wherein
the focusing lens group has positive refractive power.
13. The zoom optical system according to claim 1 , wherein a distance between the focusing lens group and an adjacent lens disposed to the object side of the focusing lens group is reduced and then increased, upon zooming from the wide-angle end state to the telephoto end state.
14. The zoom optical system according to claim 1 , wherein the following conditional expression is satisfied:
0.000<β Fw< 0.800
where βFw denotes a lateral magnification of the focusing lens group in the wide-angle end state.
15. The zoom optical system according to claim 1 , wherein the following conditional expression is satisfied:
0.100< DGXR/fXR< 1.500
where DGXR denotes a thickness, on an optical axis, of a lens group closest to the image surface in the front-side lens group.
16. The zoom optical system according to claim 1 , wherein the lens group closest to the image surface in the rear-side lens group is the third lens group and has positive refractive power.
17. The zoom optical system according to claim 1 , wherein the lens group closest to the object side in the rear-side lens group is the fifth lens group.
18. An optical device comprising the zoom optical system according to claim 1 .
19. The zoom optical system according to claim 1 , wherein
the focusing lens group includes a negative lens and has negative refractive power as a whole, and
the following conditional expressions are satisfied:
ndn+ 0.0075 ×νdn− 2.175<0
ν dn> 50.00
where ndn denotes a refractive index of a medium of the negative lens with respect to d-line, and
νdn denotes an Abbe number of the medium of the negative lens with respect to d-line.
20. A zoom optical system comprising, in order from an object side:
a first lens group having positive refractive power;
a front-side lens group;
an intermediate lens group having positive refractive power; and
a rear-side lens group,
wherein the front-side lens group is composed of one or more lens groups and has a negative lens group,
at least part of the intermediate lens group is a focusing lens group,
the rear-side lens group is composed of one or more lens groups,
upon zooming, the first lens group, the front-side lens group, the intermediate lens group, and the rear-side lens group are moved relative to an image surface, a distance between the first lens group and the front-side lens group is changed, and a distance between the intermediate lens group and the rear-side lens group is changed, and
the following conditional expression is satisfied:
1.490<( rB+rA )/( rB−rA )<3.570
where rA denotes a radius of curvature of a lens surface facing a lens surface closest to the object side in the focusing lens group with a distance in between, and
rB denotes a radius of curvature of the lens surface closest to the object side in the focusing lens group.
21. The zoom optical system according to claim 20 , wherein
the rear-side lens group is composed of two or more lens groups,
upon zooming from a wide-angle end state to a telephoto end state, the intermediate lens group moves toward the object side, and a distance between the intermediate lens group and the rear-side lens group increases, and
the following conditional expressions are satisfied:
0.170<| fF/fRF|< 10.000
0.010<( DMRT−DMRW )/ fF< 1.000
32.000≤ Wω
Tω≤ 20.000
where fF denotes a focal length of the focusing lens group,
fRF denotes a focal length of a lens group closest to the object side in the rear-side lens group,
DMRW denotes a distance between the intermediate lens group and a lens group closest to the object side in the rear-side lens group in the wide-angle end state,
DMRT denotes a distance between the intermediate lens group and the lens group closest to the object side in the rear-side lens group in the telephoto end state,
Wω denotes a half angle of view in the wide-angle end state, and
Tω denotes a half angle of view in the telephoto end state.
22. The zoom optical system according to claim 20 , wherein the following conditional expressions are satisfied:
0.001< DXRFT/fF< 1.500
Tω≤ 20.000
0.100< DGXR/fXR< 1.500
where DXRFT denotes a distance between a lens group closest to an the image surface in the front-side lens group and the focusing lens group in a telephoto end state,
fF denotes a focal length of the focusing lens group,
Tω denotes a half angle of view in the telephoto end state,
DGXR denotes a thickness, on an optical axis, of a lens group closest to the image surface in the front-side lens group, and
fXR denotes a focal length of a lens group closest to the image surface in the front-side lens group.
23. The zoom optical system according to claim 20 , wherein the following conditional expressions are satisfied:
−10.000< fF/fRF< 10.000
0.010< fF/fXR< 10.000
0.100< DGXR/fXR< 1.500
where fF denotes a focal length of the focusing lens group,
fRF denotes a focal length of a lens group closest to the object side in the rear-side lens group,
fXR denotes a focal length of a lens group closest to the image surface in the front-side lens group, and
DGXR denotes a thickness, on an optical axis, of a lens group closest to the image surface in the front-side lens group.
24. The zoom optical system according to claim 20 , wherein upon zooming from wide-angle end state to a telephoto end state, the distance between the lens group closest to the image surface in the front-side lens group and the intermediate lens group increases when approaching an intermediate focal length state from the wide-angle end state and decreases when approaching the telephoto end state from the intermediate focal length state.
25. The zoom optical system according to claim 20 , wherein the following conditional expressions are satisfied:
−10.000< fRF/fRF 2<10.000
0.100< DGXR/fXR< 1.500
where fRF denotes a focal length of a lens group closest to the object side in the rear-side lens group,
fRF2 denotes a focal length of a lens group second closest to the object side in the rear-side lens group,
DGXR denotes a thickness, on an optical axis, of a lens group closest to the image surface in the front-side lens group, and
fXR denotes a focal length of a lens group closest to the image surface in the front-side lens group.
26. The zoom optical system according to claim 20 , wherein the following conditional expressions are satisfied:
0.010<(− fXn )/ fXR< 1.000
0.100< DGXR/fXR< 1.500
where fXn denotes a focal length of a lens group with a largest absolute value of refractive power in a negative lens group of the front-side lens group,
fXR denotes a focal length of a lens group closest to the image surface in the front-side lens group, and
DGXR denotes a thickness, on an optical axis, of a lens group closest to the image surface in the front-side lens group.
27. The zoom optical system according to claim 20 , wherein the following conditional expression is satisfied:
0.390< DXnW/ZD 1<5.000
where DXnW denotes a distance between a lens group with a largest absolute value of refractive power in negative lens groups of the front-side lens group in a wide-angle end state and a lens group closest to the image surface in the front-side lens group, and
ZD1 denotes a movement amount of the first lens group upon zooming from the wide-angle end state to a telephoto end state.
28. The zoom optical system according to claim 2 , wherein
an air lens having a meniscus shape is formed by a lens surface on the image surface side of a lens closest to the image surface among lenses disposed to the object side of the focusing lens group and a lens surface closest to the object side in the focusing lens group, and
the following conditional expression is satisfied:
−0.400<β Ft< 0.400
where βFt denotes a lateral magnification of the focusing lens group in a telephoto end state.
29. The zoom optical system according to claim 20 , wherein the focusing lens group includes a negative lens having a meniscus shape with a concave surface facing the object side.
30. The zoom optical system according to claim 20 , wherein
the focusing lens group has positive refractive power.
31. The zoom optical system according to claim 20 , wherein a distance between the focusing lens group and an adjacent lens disposed to the object side of the focusing lens group is reduced and then increased, upon zooming from a wide-angle end state to a telephoto end state.
32. The zoom optical system according to claim 20 , wherein the following conditional expression is satisfied:
0.000<β Fw< 0.800
where βFw denotes a lateral magnification of the focusing lens group in a wide-angle end state.
33. The zoom optical system according to claim 20 , wherein the following conditional expression is satisfied:
0.100< DGXR/fXR< 1.500
where DGXR denotes a thickness, on an optical axis, of a lens group closest to the image surface in the front-side lens group, and
fXR denotes a focal length of a lens group closest to the image surface in the front-side lens group.
34. The zoom optical system according to claim 20 , wherein the lens group closest to the image surface in the rear-side lens group is the third lens group and has positive refractive power.
35. The zoom optical system according to claim 20 , wherein the lens group closest to the object side in the rear-side lens group is the fifth lens group.
36. An optical device comprising the zoom optical system according to claim 20 .
37. The zoom optical system according to claim 20 , wherein
the focusing lens group includes a negative lens and has negative refractive power as a whole, and
the following conditional expressions are satisfied:
ndn+ 0.0075 ×νdn− 2.175<0
ν dn> 50.00
where ndn denotes a refractive index of a medium of the negative lens with respect to d-line, and
νdn denotes an Abbe number of the medium of the negative lens with respect to d-line.
38. A method for manufacturing a zoom optical system, comprising:
arranging, in order from an object side, a first lens group having positive refractive power, a front-side lens group, an intermediate lens group having positive refractive power, and a rear-side lens group,
wherein the front-side lens group is composed of one or more lens groups and has a negative lens group,
at least part of the intermediate lens group is a focusing lens group,
the rear-side lens group is composed of one or more lens groups,
the lens groups are arranged in a lens barrel in such a manner that, upon zooming, the first lens group and the intermediate lens group are moved with respect to an image surface, a distance between the first lens group and the front-side lens group is changed, and a distance between the intermediate lens group and the rear-side lens group is changed, and
the following conditional expressions are satisfied:
0.430<| fF/fRF|< 10.000
0.420<(− fXn )/ fXR< 2.000
0.010< fF/fW< 8.000
32.000≤ Wω
where fF denotes a focal length of the focusing lens group,
fRF denotes a focal length of a lens group closest to the object side in the rear-side lens group,
fXn denotes a focal length of a lens group with a largest absolute value of refractive power in a negative lens group of the front-side lens group,
fXR denotes a focal length of a lens group closest to the image surface in the front-side lens group,
fW denotes a focal length of the zoom optical system in a wide-angle end state, and
Wω denotes a half angle of view in the wide-angle end state.
39. A method for manufacturing a zoom optical system, comprising:
arranging, in order from an object side, a first lens group having positive refractive power, a front-side lens group, an intermediate lens group having positive refractive power, and a rear-side lens group,
wherein the front-side lens group is composed of one or more lens groups and has a negative lens group,
at least part of the intermediate lens group is a focusing lens group,
the rear-side lens group is composed of one or more lens groups,
the lens groups are arranged in a lens barrel in such a manner that, upon zooming,
the first lens group, the front-side lens group, the intermediate lens group, and the rear-side lens group are moved with respect to an image surface, a distance between the first lens group and the front-side lens group is changed, and a distance between the intermediate lens group and the rear-side lens group is changed, and
the following conditional expression is satisfied:
1.490<( rB+rA )/( rB−rA )<3.570
where rA denotes a radius of curvature of a lens surface facing a lens surface closest to the object side in the focusing lens group with a distance in between, and
rB denotes a radius of curvature of the lens surface closest to the object side in the focusing lens group.