Patent ID: 7907349

Claim:
A zoom lens comprising, in order from its object side: a first lens unit having a positive refracting power, which is movable during zooming; a second lens unit having a negative refracting power, which is movable during zooming; a third lens unit having a positive refracting power, which is movable during zooming; a fourth lens unit having a positive refracting power, which is movable during zooming; a fifth lens unit having a positive refracting power, which is movable or stationary during zooming, wherein the zoom lens comprises an aperture stop, which moves integrally with the third lens unit during zooming, the first lens unit is located closer to the object side at the telephoto end than at the wide angle end; the third lens unit is located closer to the object side at the telephoto end than at the wide angle end; the first lens unit consists of a cemented lens made up of a negative lens element and a positive lens element that are arranged in order from the object side and cemented together, and the third lens unit comprises two positive lens elements; wherein the zoom lens satisfies the following conditional expression (1): −1.03<( r G1RF +r G1RR )/( r G1RF −r G1RR )<−0.30 (1) where r G1RF is a paraxial radius of curvature of a lens surface closest to the object side in the first lens unit, and r G1RR is a paraxial radius of curvature of a lens surface closest to the image side in the first lens unit.