Patent ID: 7864445

Claim:
A zoom lens, comprising, in order from an object side to an image side: a first lens unit having a positive refractive power; a second lens unit which has a negative refractive power and includes a negative lens; and a subsequent lens group including at least one lens unit, wherein at least the second lens unit is moved on an optical axis so as to increase an interval between the first lens unit and the second lens unit during zooming from a wide angle end to a telephoto end, wherein the first lens unit comprises: a front lens subunit which is not moved during focusing and has a positive refractive power; and a rear lens subunit which is moved during the focusing and has a positive refractive power, wherein the rear lens subunit includes a positive lens, wherein the positive lens included in the rear lens subunit is identified as a PR lens and the negative lens included in the second lens unit is identified as a N2 lens, and wherein the PR lens and the N2 lens are made of a material satisfying the following conditions: 60<Î½d; and âˆ’0.0015 Ã—Î½d+ 0.6425 <Î¸gF, where Î½d denotes an Abbe number of the material and Î¸gF denotes a partial dispersion ratio of the material.