Patent ID: 7667899

Claim:
A zoom lens system comprising, in order from an object side: a first lens group having a positive refractive power; a second lens group having a negative refractive power; a stop; a third lens group having a positive refractive power; and a fourth lens group having a positive refractive power, wherein zooming is performed by moving at least the first lens group, the second lens group, the stop, and the third lens group along an optical axis, during the zooming, a position of the stop on the optical axis at a wide-angle end is closer to an image plane than that at a telephoto end, a space on the optical axis at the wide-angle end between the stop and the third lens group is larger than that at the telephoto end, and the following conditional expression is satisfied: 0.4<( Pt−Pw )/ fw< 0.9 (1) where fw denotes a focal length of the whole system at the wide-angle end, Pw denotes a distance on the optical axis at the wide-angle end between the image plane and the stop, and Pt denotes a distance on the optical axis at the telephoto end between the image plane and the stop.