Patent ID: 11892611
Assignee: NIKON CORPORATION
Field: nan (nan)
Classification: CPC nan | 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 rear lens group having positive refractive power;
the rear lens group comprising, in order from the object side, a fourth lens group having positive refractive power and a fifth 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, 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;
the rear lens group comprising a focusing lens group which is moved upon carrying out focusing;
the fifth lens group consisting of one lens component constituted by a single lens or a cemented lens composed of a plurality of lenses cemented together; and
the following conditional expressions being satisfied:

4.00<f1/fw<6.500

0.100<BFw/fw<1.00

−3.000<f5/f3<−0.500

where f1 denotes a focal length of the first lens group, fw denotes a focal length of the variable magnification optical system in a wide angle end state, BFw denotes a back focus of the variable magnification optical system in the wide angle end state, f3 denotes a focal length of the third lens group, and f5 denotes a focal length of the fifth lens group.