Patent ID: 7277235
Filing Date: 2007-10-02
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, zooming from a wide-angle end state to a telephoto end state being carried out by moving each lens group along the optical axis such that a distance between the first lens group and the second lens group increases, a distance between the second lens group and the third lens group decreases, and a distance between the third lens group and the fourth lens group decreases, a zoom ratio of the zoom lens system being 5.0 or more, and the following conditional expressions being satisfied: where D 2 w denotes a distance between the second lens group and the third lens group in the wide-angle end state upon focusing on infinity, D 2 t denotes a distance between the second lens group and the third lens group in the telephoto end state upon focusing on infinity, D 3 w denotes a distance between the third lens group and the fourth lens group in the wide-angle end state upon focusing on infinity, D 3 t denotes a distance between the third lens group and the fourth lens group in the telephoto end state upon focusing on infinity, IL denotes a diagonal length of an effective image, f 3 denotes a focal length of the third lens group, f 4 denotes a focal length of the fourth lens group, and Z denotes a zoom ratio.