Patent ID: 9709779
Date: 2017-07-18
CPC Classifications: G02B

Claim:
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; an aperture stop; a third lens group having positive refractive power; and a fourth lens group having positive refractive power; upon zooming from a wide-angle end state to a telephoto end state, a distance between the first lens group and the second lens group, a distance between the second lens group and the aperture stop, a distance between the aperture stop and the third lens group, and a distance between the third lens group and the fourth lens group being varied, and a distance between the aperture stop and the fourth lens group being constant; and the following conditional expressions being satisfied: where fw denotes a focal length of the variable magnification optical system in the wide-angle end state, f1 denotes a focal length of the first lens group, f2 denotes a focal length of the second lens group, and f4 denotes a focal length of the fourth lens group.