Patent ID: 8390938
Filing Date: 2013-03-05
Classification: G02B

Abstract:
1. A zoom lens comprising a plurality of lens units, wherein the plurality of lens units comprises, in order from its object side, a first lens unit having a negative refracting power, and a second lens unit having a positive refracting power, the first lens unit comprises a biconcave negative lens, the second lens unit comprises four lens elements comprising a positive lens and a negative lens, the total number of lens elements in the second lens unit is four, during zooming from the wide angle end to the telephoto end, a distance between the lens units changes, and the second lens unit moves toward the object side, the zoom lens comprises an aperture stop that moves integrally with the second lens unit during zooming from the wide angle end to the telephoto end, and the zoom lens satisfies the following conditional expressions (1A) and (3A): where r 11a is a paraxial radius of curvature of an object side surface of the biconcave negative lens in the first lens unit, r 11b is a paraxial radius of curvature of an image side surface of the biconcave negative lens in the first lens unit, f t is a focal length of the entire zoom lens system at the telephoto end, and f w is a focal length of the entire zoom lens system at the wide angle end.