Patent ID: 7164539

Claim:
A zoom lens having an image side and an object side and formed of only three lens groups arranged along an optical axis in order from the object side as follows: a first lens group having negative refractive power and including an aspheric surface; a second lens group having positive refractive power and including an aspheric surface; and a third lens group having positive refractive power; wherein the second lens group includes a stop that controls the amount of light that passes through the zoom lens; when zooming from the wide-angle end to the telephoto end, the first lens group moves closer to the second lens group and the second lens group moves relative to the third lens group so that the second lens group and the third lens group become farther apart; the third lens group moves toward the object side during focusing from a distant object to a nearby object; the first lens group includes, in order from the object side, a lens element having negative refractive power and a lens element having positive refractive power; the second lens group includes, in order from the object side, a biconvex lens element, a biconcave lens element cemented to the biconvex lens element, and a lens element that forms a separate lens component having positive refractive power and is made of plastic; the third lens group consists of a single lens element having positive refractive power and made of plastic; and the following conditions are satisfied: v 3 −v 4>15 |f 3 /v 3 +f 4 /v 4|<0.07 fw/|f 5|<0.18 where v 3 is the Abbe number at the d-line of said biconvex lens element; v 4 is the Abbe number at the d-line of said biconcave lens element; f 3 is the focal length of said biconvex lens element; f 4 is the focal length of said biconcave lens element; fw is the focal length of the zoom lens at the wide-angle end; and f 5 is the focal length of the separate lens component of the second lens group.