Zoom optical system, optical device and method for manufacturing the zoom optical system
A zoom optical system comprises, 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. 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, distances between the first lens group and the front-side lens group, between the front-side lens group and the intermediate lens group, and between the intermediate lens group and the rear-side lens group change. The following conditional expressions are satisfied: −10.000< fF/fRF <10.000 0.010<| fF/fXR |<10.000 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, and fXR denotes a focal length of a lens group closet to an image surface in the front-side lens group.
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, a distance between the first lens group and the front-side lens group is changed, a distance between the front-side lens group and the intermediate 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:
−10.000 <fF/fRF< 10.000
0.010 <|fF/fXR|< 10.000
0.100 <DGXR/fXR <1.500
2.250< TLW/ZD 1<10.000
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,
fXR denotes a focal length of a lens group closet to an image surface in the front-side lens group,
DGXR denotes a thickness of the lens group closest to an image in the front-side lens group on an optical axis,
TLW denotes an entire lentght of the optical system in a wide angle end state, and
ZD1 denotes a movement amount of the first lens group upon zooming from the wide angle end state to a telephoto end state.
2. The zoom optical system according to claim 1 , wherein the following conditional expression is satisfied:
−10.000 <fRF/fRF 2<10.000
where
fRF2 denotes a focal length of a lens group second closest to the object side in the rear-side lens group.
3. The zoom optical system according to claim 1 , wherein the following conditional expression is satisfied:
32.000 ≤Wω
where
Wω: a half angle of view in the wide angle end state.
4. The zoom optical system according to claim 1 , wherein the following conditional expression is satisfied:
Tω≤ 20.000
where
Tω denotes a half angle of view in telephoto end state.
5. The zoom optical system according to claim 1 , wherein the following conditional expression is satisfied:
0.000 <βFw< 0.800
where
βFw denotes a lateral magnification of the focusing lens group in the wide angle end state.
6. The zoom optical system according to claim 1 , wherein the following conditional expression is satisfied:
0.010 <fF/fW< 8.000
where
fW denotes a focal length of the entire system in wide angle end state.
7. The zoom optical system according to claim 1 , wherein the following conditional expression is satisfied:
0.420<(− fXn )/ fXR< 2.000
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.
8. The zoom optical system according to claim 1 , wherein the following conditional expression is satisfied:
0.010<(− fXn )/ fXR< 1.000
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.
9. The zoom optical system according to claim 1 , wherein the following conditional expression is satisfied:
0.170 <|fF/fRF |<10.000.
10. The zoom optical system according to claim 1 , wherein the following conditional expression is satisfied:
0.010 <fF/fXR< 10.000.
11. An optical device comprising the zoom optical system according to claim 1 .
12. A method for manufacturing a zoom optical system, comprising:
arranging, in a lens barrel and 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,
the front-side lens group being composed of one or more lens groups and having a negative lens group,
at least part of the intermediate lens group being a focusing lens group,
the rear-side lens group being composed of one or more lens groups,
the arrangement being such that upon zooming, a distance between the first lens group and the front-side lens group is changed, a distance between the front-side lens group and the intermediate lens group is changed, and a distance between the intermediate lens group and the rear-side lens group is changed; and
satisfying the following conditional expressions:
−10.000 <fF/fRF< 10.000
0.010 <|fF/fXR|< 10.000
0.100 <DGXR/fXR <1.500
2.250< TLW/ZD 1<10.000
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,
fXR denotes a focal length of a lens group closet to an image surface in the front-side lens group,
DGXR denotes a thickness of the lens group closest to an image in the front-side lens group on an optical axis,
TLW denotes an entire lentght of the optical system in a wide angle end state, and
ZD1 denotes a movement amount of the first lens group upon zooming from the wide angle end state to a telephoto end state.