Patent ID: 6972908
Filing Date: 2005-12-06
Classification: G02B

Abstract:
1. A zoom lens comprising, arranged along an optical axis in order from the object side: a first lens group having negative refractive power; a second lens group having positive refractive power; and a third lens group having positive refractive power; wherein the first lens group and the second lens groups move along the optical axis during zooming; the first lens group includes, arranged along the optical axis in order from the object side, a first lens component having negative refractive power and a second lens component having positive refractive power; the second lens group includes, arranged along the optical axis in order from the object side, a third lens component that consists of a lens element made of glass, having a convex surface on the optical axis on the object side, and being aspheric on at least one side, and a fourth lens component that consists of, arranged along the optical axis, a lens element that is cemented on its image side to a lens element that has a concave surface on its image side; the third lens group consists of a fifth lens component with a convex surface on each side; and the following conditions are satisfied: where Tt is the distance from the most object-side lens surface of the zoom lens to the image plane at the telephoto end when the zoom lens is focused on an object at infinity, fw is the focal length of the zoom lens at the wide-angle end when the zoom lens is focused on an object at infinity, and f2g is the focal length of the second lens group.