Patent ID: 7126762

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, collectively referred to as lens units, wherein, magnification varying is performed by varying distances along an optical axis between at least any two of the lens units, during magnification varying from a wide-angle limit to a telephoto limit, the third lens unit moves to the object side, and the first and second lens units move with locus of a convex to the image side, the third lens unit comprises at least two lens elements including a third lens unit object side lens element which is a positive lens element disposed at a position closest to the object side and whose high-curvature surface faces the object side and a third lens unit image side lens element which is a negative lens element disposed at a position closest to the image side and concave in relation to the image side, and the following conditions are satisfied: 7.0 <L W /f W <9.0 (1) 1.5 <L T /f T <2.1 (2) (here, Z=f T /f W >5.0) where L W is an optical overall length at a wide-angle limit, f W is a focal length of an entire lens system at the wide-angle limit, L T is an optical overall length at a telephoto limit, and f T is a focal length of the entire lens system at the telephoto limit Z is a magnification variation ratio at the wide-angle and telephoto limits.