Patent ID: 8045276

Claim:
A zoom lens with three lens groups, along an optical axis thereof, comprising in order from an object side to an image side, a negative power first lens group, a positive power second lens group and a positive power third lens group, wherein the first lens group comprising two lens, a negative power first biconcave lens with a first surface facing the object side and a positive power second meniscus lens with a first convex surface facing the object side along the optical axis from the object side to the image side; the second lens group comprising three lens, a biconvex cylindrical third lens, a biconcave fourth lens and a fifth meniscus lens with its concave surface facing the object side while an image side lens surface of the third lens connects with an object side lens surface of the fourth lens; the third lens group comprising a lens that is a positive power sixth lens; wherein the first lens group, the second lens group, and the third lens group each has at least one aspherical surface; while changing from a WIDE position to a TELE position of the zoom lens with three lens groups, the distance between the first lens group and the second lens group is reduced while the distance between the second lens group and the third lens group is increased and the distance between the third lens group and an imaging forming plane is reduced; focal length of the first lens group, the second lens group, and the third lens group meets the conditions: 2.5 <  f G ⁢ ⁢ 1 f W  < 3.0 ; 1.1 <  f G ⁢ ⁢ 1 f G ⁢ ⁢ 2  < 1.7 ; 1.0 < f G ⁢ ⁢ 3 f T < 1.3 ; and 0.08 <  f 3 v 3 + f 4 v 4  < 0.28 wherein f W : focal length in the WIDE position; f G1 : focal length of the first lens group; f G2 : focal length of the second lens group; f T : focal length in the TELE position; f G3 : focal length of the third lens group; f 3 : focal length of the third lens; f 4 : focal length of the fourth lens; v 3 : Abbe number of the third lens; v 4 : Abbe number of the fourth lens.