Patent ID: 7492524
Filing Date: 2009-02-17
Classification: G02B

Abstract:
1. A zoom lens system comprising, in order from an object: a first lens group having positive refractive power; 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; upon zooming from a wide-angle end state to a telephoto end state, a distance between the first lens group and the second lens group varying, a distance between the second lens group and the third lens group varying, and a distance between the third lens group and the fourth lens group varying; the third lens group comprising, in order from the object, a front group having positive refractive power, and a rear group having negative refractive power; wherein the rear group is movable in a direction substantially perpendicular to the optical axis, and the following conditional expressions are satisfied: where fw denotes a focal length of the zoom lens system in the wide-angle end state, ft denotes a focal length of zoom lens system in the telephoto end state, and f