Patent ID: 6940656

Claim:
A zoom lens formed of only four lens groups, in order from the object side along an optical axis, as follows: a first lens group having positive refractive power and that includes on the object side a biconcave lens element; a second lens group having negative refractive power; a third lens group having positive refractive power; and a fourth lens group having positive refractive power; wherein the first lens group and the fourth lens group do not move during zooming; the second lens group and the third lens group are moved along the optical axis during zooming; and the following conditions are satisfied: L/f w >1.17 N L1 >1.75 v L1 >38 where L is the distance between two points of an image formed by the zoom lens on the image plane of the zoom lens that are diametrically opposite each other with respect to the optical axis of the zoom lens, f w is the focal length of the zoom lens at its wide-angle end, N L1 is the refractive index at the e-line of the material of the object side lens element of the zoom lens, and v L1 is the Abbe number at the d-line of the material of the object side lens element of the zoom lens.