Patent ID: 7474472
Filing Date: 2009-01-06
Classification: G02B

Abstract:
1. A zoom lens, comprising, in order from an object side thereof: a first lens group having negative refracting power, a second lens group having positive refracting power, and a third lens group having positive refracting power, wherein, upon zooming from a wide-angle end to a telephoto end of said zoom lens, said first lens group, said second zoom lens and said third lens group each move along an optical axis of said zoom lens, a spacing between said first lens group and said second lens group becomes narrow, and a spacing between said second lens group and said third lens group becomes wide, wherein: said first lens group comprises one single lens that is a double-concave negative lens or two lenses: a double-concave negative lens and a positive lens, said first lens group includes a total of at most two lenses, said second lens group comprises two positive lenses and one negative lens, said second lens group includes a total of three lenses, at least one of said two positive lenses in said second lens group has an aspheric lens surface, and the following condition is satisfied: where h 1w is a height of an axial marginal ray at an entrance surface in the first lens group at the wide-angle end and upon focusing on the farthest distance, and C jw is a length from the entrance surface in the first lens group to an image plane at the wide-angle end and upon focusing on the farthest distance.