Patent ID: 7212349
Filing Date: 2007-05-01
Classification: G02B

Abstract:
1. A zoom lens system comprising, in order from an object along an optical axis: 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, when a state of lens group positions varies from a wide-angle end state to a telephoto end state, the first lens group and the second lens group being moved such that a distance between the first lens group and the second lens group decreases, and a distance between the second lens group and the third lens group increases, the second lens group being composed of at least two positive lens elements and one negative lens element, and at least one positive lens element and the negative lens element in the second lens group satisfying the following conditional expressions: where θgF2p denotes a partial dispersion ratio of a material of the at least one positive lens element in the second lens group, νd2p denotes Abbe number of the material of the at least one positive lens element in the second lens group at d-line (wavelength λ=587.6 nm), θgF2n denotes a partial dispersion ratio of a material of the negative lens element in the second lens group, and νd2n denotes Abbe number of the material of the negative lens element in the second lens group at d-line (wavelength λ=587.6 nm).