Patent ID: 6943960
Filing Date: 2005-09-13
Classification: G02B

Abstract:
1. A zoom lens formed of only three lens groups, arranged along an optical axis in order from the object side, as follows: a first lens group of negative refractive power; a second lens group of positive refractive power; and a third lens group of negative or positive refractive power; wherein the first and the second lens groups are moved so that the first and second lens groups become closer together during zooming from the wide-angle end to the telephoto end; the first lens group includes at least one lens element that includes at least one aspheric lens surface; and the shape of said at least one aspheric lens surface is given by an aspheric lens equation that includes at least one non-zero coefficient of an even power of Y, and at least one non-zero coefficient of an odd power of Y, where Y is the distance of a point on the aspheric lens surface from the optical axis.