Patent ID: 11933950
Assignee: NIKON CORPORATION
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. A variable magnification optical system comprising, in order from an object side, a first lens group having positive refractive power, a second lens group having negative refractive power, a third lens group having positive refractive power, and a fourth lens group having negative refractive power;
upon varying a magnification, a distance between the first lens group and the second lens group being varied, a distance between the second lens group and the third lens group being varied, and a distance between the third lens group and the fourth lens group being varied;
upon focusing, the fourth lens group being moved; and
the following conditional expressions being satisfied:

0.55<f2/f4<1.40

1.40<f1/fw<2.80

0.82<(−f2)/f3<1.30

2.00<f1/(−f2)<3.50

where f1 denotes a focal length of the first lens group; f2 denotes a focal length of the second lens group; f3 denotes a focal length of the third lens group; f4 denotes a focal length of the fourth lens group; and fw denotes a focal length of the variable magnification optical system in the wide angle end state;
the variable magnification optical system further comprising a vibration reduction lens group that is movable to have a displacement component in a direction perpendicular to the optical axis,
wherein the following conditional expression is satisfied:

0.70<|fvr|/f3<1.60

where fvr denotes a focal length of the vibration reduction lens group.