Patent ID: 6909846

Claim:
A zoom lens system comprising, in order from an object; a first lens group having negative refractive power; an aperture stop; a second lens group having positive refractive power; and a third lens group having positive refractive power; wherein when the state of lens group positions varies from a wide-angle end state to a telephoto end state; the first lens group and the second lens group are moved and the third lens group is fixed such that a distance between the first lens group and the second lens group varies; and a distance between the second lens group and the third lens group increases; and wherein the second lens group is composed of four lenses or less; the second lens group includes a diffractive optical surface formed on a lens surface except the most object side lens surface; and the following conditional expression is satisfied: 0.2 <C/fw <2.0 where C denotes the effective diameter of the diffractive optical surface, and fw denotes the focal length of the zoom lens system in the wide-angle end state.