Patent ID: 7450319

Claim:
A zoom lens comprising, in order from an object side thereof, a first lens group having positive refracting power, a second lens group having negative refracting power and a third lens group having positive refracting power, wherein: there is an aperture stop located between said second lens group and said third lens group; upon zooming from a wide-angle end to a telephoto end of the zoom lens, said first lens group moves in unison, and said second lens group moves in unison, and said first lens group and said second lens group are positioned nearer to the object side at said telephoto end than said wide-angle end with an increasing spacing between said first lens group and said second lens group and a decreasing spacing between said second lens group and said third lens group; and said zoom lens is a three lens group type zoom lens that satisfies the following conditions (1) and (2): 0.7< f 1 /f t <1.2 (1) 0.3< m 1 /f t <0.45 (2) where f 1 is a focal length of the first lens group, f t is a focal length of the whole zoom lens system at the telephoto end, and m 1 is a difference in the position of the first lens group between at the wide-angle end and at the telephoto end, provided that a plus sign is indicative of movement of the first lens group toward the object side.