Patent ID: 7817350

Claim:
A zoom lens system that forms an optical image of an object with variable magnification and that, in order from the object side to the image side, comprises: a first lens unit having negative optical power; a second lens unit that has positive optical power and that contains a bi-convex lens element composed of a resin material and serving as the most image side lens element; and a third lens unit having positive optical power, wherein the lens units move respectively along an optical axis in such a manner that intervals between the individual lens units should vary so that the variable magnification is achieved, and the following condition (I-1) is satisfied: |( R 2mi1 +R 2mi2 )/( R 2mi1 −R 2mi2 )|<1.0 (I-1) where, R 2mi1 is a radius of curvature on the object side of the most image side lens element of the second lens unit, and R 2mi2 is a radius of curvature on the image side of the most image side lens element of the second lens unit.