Patent ID: 7916399

Claim:
A zoom lens comprising: a first lens group having a positive refractive power; a second lens group having a negative refractive power; a third lens group having a negative refractive power; and a fourth lens group having a positive refractive power, in order from an object side of the zooming lens, wherein the second lens group monotonically moves toward an image side of the zooming lens along an optical axis of the zooming lens for a zooming from a wide-angle end to a telephoto end of the zooming lens, wherein the third lens group moves along the optical axis to compensate of a fluctuation of an image surface of the zooming lens resulting from the zooming of the second lens group, and wherein at least one positive lens having an optical material satisfying conditional expressions (1) and (2) shown below is included in at least one of the first lens group and the fourth lens group which are positive lens groups: vd>60 (1) θ C,A′< 0.001198 vd+ 0.2765 (2) wherein vd represents an Abbe number of the optical material at the d-line, θC,A′ represents a partial dispersion ratio when a partial dispersion of the optical material is set to (nC−nA′), nC represents a refractive index of the optical material at the C-line, and nA′ represents a refractive index of the optical material at the A′-line.