Patent ID: 7453648

Claim:
A zoom lens system for forming an optical image of an object with a variable magnification, in order from the object side to the image side, comprising: a first lens unit having negative optical power; a second lens unit having positive optical power; and a third lens unit having positive optical power, wherein in zooming from a wide-angle limit to a telephoto limit, the lens units move respectively along an optical axis in such a manner that an interval between the first lens unit and the second lens unit decreases while an interval between the second lens unit and the third lens unit changes so that the variable magnification is achieved, the first lens unit comprises: one object side negative lens element; and one image side positive lens element with a convex surface facing the object side, the second lens unit has at least three lens elements, each of the two lens elements constituting the first lens unit has an aspheric surface, and the following conditions (1) and (2) are satisfied: n12>1.88 (1) ν12<26 (2) where, n12 is a refractive index of the image side positive lens element of the first lens unit, and ν12 is an Abbe number of the image side positive lens element of the first lens unit.