Patent ID: 8395848

Claim:
A zoom lens system having a plurality of lens units each composed of at least one lens element and, in order from an object side to an image side, comprising: a first lens unit having negative optical power and consisting of two lens elements; 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 during image taking, at least the first lens unit and the second lens unit move along an optical axis, wherein on the image side relative to the second lens unit, an aperture diaphragm is arranged that moves along the optical axis integrally with the second lens unit during zooming, wherein the second lens unit, in order from the object side to the image side, consists of a first cemented lens element constructed by cementing two lens elements with each other and a second cemented lens element constructed by cementing two lens elements with each other, and wherein the following condition (28) is satisfied: 2.00< f G2a /f G2b <3.00 (28) where, f G2a is a focal length of the first cemented lens element, and f G2b is a focal length of the second cemented lens element.