Patent ID: 11892610
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 rear lens group;
upon zooming, a distance between the first lens group and the second lens group, a distance between the second lens group and the third lens group, and a distance between the third lens group and the rear lens group being varied, and the second lens group and the third lens group being moved; and
the following conditional expression being satisfied:

5.00<f1/(−f2)<10.00

where f1 denotes a focal length of the first lens group, and f2 denotes a focal length of the second lens group,
wherein at least one lens satisfies the following conditional expressions:

1.928<ndh 

28.60<νdh 

where ndh denotes refractive index at d-line (wavelength λ=587.6 nm) of the lens, and νdh denotes Abbe number at d-line (wavelength λ=587.6 nm) of the lens.