Patent ID: 8542449

Claim:
An enhanced variable power zoom lens having an image plane and an optical axis, the zoom lens operable from a wide-angle position to a telephoto position, the zoom lens comprising: a foremost or first lens group of positive refractivity, a second lens group of negative refractivity, a third lens group of positive refractivity, a fourth lens group of negative refractivity, and a fifth lens group, the first through fifth lens groups arranged in sequence from a position closer to an object; the fourth lens group being moved toward the image plane for focusing on from the infinity to a proximity of the object, and part of the third lens group being moved in a direction orthogonal to the optical axis for shifting an image, wherein the zoom lens meets requirements as expressed in the following formulae: 0.8 <f 3 B/f 3<4.0, and 0.1 <f 3 B/ft< 0.3 where f 3 B is the focal length of the second foremost lens subset of the third lens group, f 3 is the focal length of the third lens group, and ft is the focal length of the entire optics of the first through fifth lens groups at the telephoto position.