Patent ID: 7768718

Claim:
A zoom lens comprising: a first group having a negative refractive power; a diaphragm; and a second group having a positive refractive power, wherein: the first group, the diaphragm and the second group are arranged in order from an object side, upon varying a power from a wide angle end to a telephoto end, power variation is executed by moving the second group toward the object side along an optical axis, correction of an image plane associated with the power variation is made by moving the first group along the optical axis, the second group comprises: a first lens having a positive refractive power, a cemented lens formed of a second lens having a positive refractive power and a third lens having a negative refractive power, a fourth lens having a negative refractive power, wherein a surface of the fourth lens on the object side has a convex shape and a surface of the fourth lens on an image side has a concave shape, and a fifth lens having a positive refractive power, and the first lens, the cemented lens, the fourth lens and the fifth lens are arranged in order from the object side, and wherein the following conditional expressions are satisfied: 20.0<ν d2f <45.0 (2) where ν d2f denotes an Abbe number of a lens, closest to an image side, of the second group with respect to d-line, and | R 25r |>3 |R 25f | where R 25r denotes a radius of curvature of the fifth lens on the image side and R 25f denotes a radius of curvature of the fifth lens on the object side.