Patent ID: 7102830
Filing Date: 2006-09-05
Classification: G02B

Abstract:
1. An electronic imaging system comprising a zoom lens and an image pickup device located on an image side of the zoom lens, wherein: the zoom lens comprises, 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, and further comprises an aperture stop that is interposed between the first lens group and the second lens group and moves in unison with the second lens group, for zooming from a wide-angle end to a telephoto end of the zoom lens upon focused on an object point at infinity, the second lens group moves only toward the object side and the third lens group moves in a locus different from that of the second lens group while a spacing between adjacent lens groups varies, the second lens group comprises, in order from an object side thereof, four lens elements, a positive first lens element L the third lens group moves independently during focusing, and the second lens group satisfies the following conditions (1), (2) and (3): where ν 23 is a d-line based Abbe number of the third lens element L 23 in the second lens group, ν 24 is a d-line based Abbe number of the fourth lens element L 24 in the second lens group, R 23F is an axial radius of curvature of an object side-surface of the third lens element L 23 in the second lens group, R 23R is an axial radius of curvature of an image side-surface of the third lens element L 23 in the second lens group, L is a diagonal length of an effective image pickup area of the image pickup device, and f 2R is a composite focal length of the third lens element L 23 and the fourth lens element L 24 in the second lens group.