Enhanced variable power zoom lens

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<f3B/f3<4.0, and
• 0.1<f3B/ft<0.3
• where f3B is the focal length of the second foremost lens subset of the third lens group, f3 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.