Patent ID: 7443606
Filing Date: 2008-10-28
Classification: G02B

Abstract:
1. A zoom lens system comprising, in order from an object side to an image side: a first lens unit of positive optical power; a second lens unit of negative optical power; a third lens unit of positive optical power; and a fourth lens unit of positive optical power, wherein zooming is performed by moving each of the lens units, wherein the first lens unit moves during zooming so that position of the first lens unit, which corresponds to a telephoto end, is closer to the object side than position of the first lens unit, which corresponds to a wide-angle end and the third lens unit moves during zooming so that position of the third lens unit, which corresponds to a telephoto end, is closer to the object side than position of the third lens unit, which corresponds to a wide-angle end, and wherein a ratio β2z of an imaging magnification of the second lens unit corresponding to the telephoto end, to an imaging magnification of the second lens unit corresponding to the wide-angle end, a ratio β3z of an imaging magnification of the third lens unit corresponding to the telephoto end, to an imaging magnification of the third lens unit corresponding to the wide-angle end, a focal length f wherein the third lens unit moves to have a component in a direction perpendicular to an optical axis, and wherein an image formed by the zoom lens system is changed by movement of the third lens unit.