Patent ID: 7230772
Filing Date: 2007-06-12
Classification: G02B

Abstract:
1. 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: wherein f f f f 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.