Patent ID: 6522476
Filing Date: 2003-02-18
Classification: G02B

Abstract:
A three-group zoom lens having, from an object side, a first group lens, a second ground lens and a third group lens,said first lens group having a negative power, said second lens group having a positive power, said second lens group including an aperture stop, said third lens group consisting of a single positive lens, wherein, when a distance to be focused is infinity, only said first lens group and said second lens group move for zooming, wherein said single positive lens has at least one aspherical surface with a positive power that is stronger at a portion farther from an optical axis of said single positive lens, wherein said zoom lens satisfies the following conditions: âˆ’0.852/f1and5.0<f3/fw<8.0, wherein, fw represents a focal length when said zoom lens is positioned at a wide-extremity, f1 represents a focal length of said first lens group, f2 represents a focal length of said second lens group, and f3 represents a focal length of said third lens group.