Patent ID: 7697215

Claim:
A zoom lens system, in order from an object side, comprising: a first lens unit of negative optical power, the first lens unit, in order from the object side, consisting of a first lens element having a negative meniscus shape with a surface of strong curvature facing the image side, and a second lens element which is a positive lens element with a surface of strong curvature facing the object side; a second lens unit of positive optical power, the second lens unit including at least one cemented lens element, the second lens unit including a most object side surface convex to the object side and a most image side surface convex to the image side; and a third lens unit of positive optical power, the third lens unit comprising solely one positive lens element, wherein the lens units move respectively along an optical axis so that a magnification is changed with changing a distance between the respective lens units, wherein the first lens unit moves with locus of a convex to image side, while the second lens unit monotonically moves to object side in magnification change from a wide-angle limit to a telephoto limit, and wherein the following condition is satisfied: 1.9 <f G2 /f W <2.4 (2) (where, Z=f T /f W >2.5) wherein, f G2 is a focal length of the second lens unit, f T is a focal length of the entire lens system at a telephoto limit, and f W is a focal length of the entire lens system at a wide-angle limit.