Patent ID: 8300321

Claim:
A zoom lens system comprising a negative first lens group, a positive second lens group, and a positive third lens group, in that order from the object side, wherein upon zooming from the short focal length extremity to the long focal length extremity, each of the first through third lens groups move along the optical axis, wherein said second lens group comprises a positive lens element, a negative lens element and a negative lens element, in that order from the object side, and wherein the following conditions (1) and (2) are satisfied: 2.0 <|VD 1 t−VD 1 w |/( ft/fw )<3.4 (1), and 0.89 <|m 2 w/m 3 w| (2), wherein VD1 t designates the distance along the optical axis, at the long focal length extremity, from the surface on the image side of the lens element provided closest to the image side within said first lens group to the surface on the object side of the positive lens element provided closest to the object side within said second lens group; VD1 w designates the distance along the optical axis, at the short focal length extremity, from the surface on the image side of the lens element provided closest to the image side within said first lens group to the surface on the object side of the positive lens element provided closest to the object side within said second lens group; ft designates the focal length of the entire said zoom lens system at the long focal length extremity; fw designates the focal length of the entire said zoom lens system at the short focal length extremity; m2 w designates the lateral magnification of said second lens group at the short focal length extremity when focused on an object at infinity; and m3 w designates the lateral magnification of said third lens group at the short focal length extremity when focused on an object at infinity.