Patent ID: 8064144

Claim:
A zoom lens system, in order from an object side to an image side, comprising a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, and a fourth lens unit having positive optical power, wherein in zooming from a wide-angle limit to a telephoto limit, all of the first lens unit, the second lens unit, the third lens unit and the fourth lens unit move along an optical axis, and wherein the following conditions are satisfied: 0.15< dG 3/ dG< 0.27 (8) here, 16<f T /f W and ω>35 where, dG 3 is an optical axial center thickness of the third lens unit, dG is a sum of the optical axial thicknesses of the first lens unit, the second lens unit, the third lens unit and the fourth lens unit, ω is a half view angle (°) at a wide-angle limit, f T is a focal length of the entire system at a telephoto limit, and f W is a focal length of the entire system at a wide-angle limit, wherein the third lens unit moves in a direction perpendicular to the optical axis.