Patent ID: 7230772

Claim:
A wide-angle zoom lens system comprises a negative first lens group, a positive second lens group, a negative third lens group and a positive fourth lens group, in this order from an object; wherein upon zooming from the short focal length extremity to the long focal length extremity, a distance between said negative first lens group and said positive second lens group decreases, a distance between said positive second lens group and said negative third lens group increases, and a distance between said negative third lens group and said positive fourth lens group decreases; and wherein said wide-angle zoom lens system satisfies the following conditions: 1.1 <|f 1 |/fw <2.0( f 1 <0) 2.0 <f 4 / fw <3.5 2.5 <fBw/fw <3.5 0.5 <f 2 / ft< 1.2 0.5 <|f 3 |/ft< 1.4( f 3 <0) wherein f 1 designates the focal length of said negative first lens group; f 2 designates the focal length of said positive second lens group; f 3 designates the focal length of said negative third lens group; f 4 designates the focal length of said positive fourth lens group; ft designates the focal length of the entire wide-angle zoom lens system at the long focal length extremity; fw designates the focal length of the entire wide-angle zoom lens system at the short focal length extremity; and fBw designates the equivalent air thickness from the most image-side lens surface to the image plane at the short focal length extremity.