Patent ID: 8223437
Filing Date: 2012-07-17
Classification: G02B

Abstract:
1. A wide-angle zoom lens system comprises a negative first lens group, a positive second lens group, and a positive third lens group, in this order from an object, wherein upon zooming from the short focal length extremity to the long focal length extremity, each of said negative first lens group, said positive second lens group and said positive third lens group move along the optical axis thereof while a distance between said negative first lens group and said positive second lens group decreases, and a distance between said positive second lens group and said positive third lens group also decreases; wherein said wide-angle zoom lens system satisfies the following condition: wherein f3 designates the focal length of said positive third lens group; and fw designates the focal length of the entire wide-angle zoom lens system at the short focal length extremity; wherein said positive second lens group is moved toward the image in order to perform a focusing operation from an object at infinity to an object at a closer distance.