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

Claim 4:
5. 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, a fourth lens group having negative refractive power, and a fifth lens group having positive 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, a distance between the third lens group and the fourth lens group being varied, and a distance between the fourth lens group and the fifth lens group being varied;
upon focusing, the fourth lens group being moved;
a vibration reduction lens group being movable to have a displacement component in a direction perpendicular to the optical axis; and
the following conditional expressions being satisfied:

1.067≤|fvr|/f3<1.60

0.55<f2/f4<1.40

where f3 denotes a focal length of the third lens group; fvr denotes a focal length of the vibration reduction lens group; f2 denotes a focal length of the second lens group; and f4 denotes a focal length of the fourth lens group.