Patent ID: 7830615
Filing Date: 2010-11-09
Classification: G02B

Abstract:
1. A zoom lens comprising: a first lens group having a negative refractive power, a second lens group having a positive refractive power, and a third lens group having a positive refractive power, in that order from an object side to an image side, wherein, during zooming from a wide-angle end to a telephoto end, the first lens group is moved, and the second lens group is moved to the object side, in an optical-axis direction such that an air distance between the first and second lens groups is decreased and an air distance between the second and third lens groups is increased, wherein the second lens group includes a first lens having a positive refractive power, a second lens having a negative refractive power, a third lens having a negative refractive power, and a fourth lens having a positive refractive power, in that order from the object side to the image side, wherein the third and fourth lenses of the second lens group are bonded to each other to serve as a cemented lens, and wherein the zoom lens is configured to satisfy Conditional Expressions (1) and (2) as follows, where f2 is a focal length of the second lens group, f2R is a combined focal length of the cemented lens including the third and fourth lenses of the second lens group, L2 is an overall length on an optical axis of the second lens group, and LT is an optical overall length at the telephoto end.