Patent ID: 8300322

Claim:
A variable magnification optical system comprising: a first lens group having negative refractive power; a stop; and a second lens group having positive refractive power, which are arranged from the object side of the variable magnification optical system in the order mentioned above, wherein the magnification of the variable magnification optical system is changed by changing a distance between the first lens group and the second lens group in the direction of an optical axis, and wherein the first lens group includes a plastic lens having negative refractive power, and wherein the second lens group includes a plastic lens having positive refractive power, and wherein the following formulas (1) and (2) are satisfied: 5.0 <fpp/fw< 7.5 (1); and −7.0 <fpn/fw<− 6.0 (2), where fpn is the focal length of the plastic lens having negative refractive power, fpp is the focal length of the plastic lens having positive refractive power, and fw is the focal length of the entire system of the variable magnification optical system at a wide angle end.