Patent ID: 6919994

Claim:
A zoom lens comprising three lens groups, in order from the object side, as follows: a first lens group of negative refractive power; a second lens group of positive refractive power; and a third lens group of positive refractive power; wherein the first lens group includes, in order from the object side, a lens element of negative refractive power and a lens element of positive refractive power; the second lens group includes a lens component of positive refractive power, a lens component that includes a first lens element of positive refractive power that is intimately bonded to a second lens element of negative refractive power, a lens component of negative refractive power, and a stop for controlling the amount of light that passes through the zoom lens; the distance between the third lens group and an image plane of the zoom lens remains substantially constant during zooming while the zoom lens is focused at infinity, the third lens group includes a lens component having positive refractive power, and the third lens group moves toward the object side from a reference position during focusing from infinity to a near point; at least two lens surfaces of each of the first and second lens groups are aspheric; the first and the second lens groups are moved so that the first and second lens groups become closer together and so that the second and third lens groups become farther apart during zooming from the wide-angle end to the telephoto end; and the following conditions are satisfied: 0.4 <f w /|f 1 |<0.6 0.25 <f 2 /f 3 <0.45 where f w is the focal length of the zoom lens at the wide-angle end, f 1 is the focal length of the first lens group, f 2 is the focal length of the second lens group, and f 3 is the focal length of the third lens group.