Patent ID: 8085475

Claim:
A zoom lens system comprising a plurality of lens units and performing zooming by changing intervals among the lens units, wherein the plurality of lens units, in order from an object side to an image side, includes: a first lens unit having negative optical power; a second lens unit having positive optical power; a third lens unit having positive optical power; and a fourth lens, and the following conditions are satisfied: 1.4 <DL/YM< 2.5 (10) 1.2<BF W /YM< 1.6 (11) (where, 100<2ω W <140) where, DL is an effective diameter of the lens surface closest to the image side, BF W is the back focus at a wide-angle limit, YM is the maximum image height at a wide-angle limit, and ω W is a half view angle (°) at a wide-angle limit.