Patent ID: 8576501

Claim:
A wide-angle optical system comprising: a front lens group; a rear lens group; and an aperture stop arranged between the front lens group and the rear lens group, wherein the front lens group includes at least two negative lenses and at least one positive lens, at least one of a positive lens or positive lenses in the front lens group includes at least one aspheric surface, and the front lens group satisfies the following conditional expression: vdp <29, where vdp is a minimum Abbe number of the positive lens or positive lenses in the front lens group, wherein the wide-angle optical system satisfies the following conditional expression: Y′/TL > 0.1, where Y′ is a maximum image height, and TL is a distance along an optical axis from a surface vertex on a lens surface arranged at a closest position to an object, to an image plane, where a back focal length is measured in an air conversion length, and wherein the at least one positive lens satisfies the following conditional expression: |Hp|/Rp> 0.65, where Hp is a height (a distance from an optical axis) of a principal ray of a light flux corresponding to a maximum image height on an object-side surface of the at least one positive lens, and Rp is a maximum effective radius of the object-side surface of the at least one positive lens.