Patent ID: 8223439
Filing Date: 2012-07-17
Classification: G02B

Abstract:
1. An optical system comprising, in order from an object side to an image side: a first lens unit; a stop; and a second lens unit, wherein the first lens unit includes: wherein the second lens unit includes a positive lens Gp having a positive refractive power, wherein a material of each of the negative lens Gn and the positive lens Gp satisfies the following condition: where “νd” denotes an Abbe number of a lens material and “θgF” denotes a relative partial dispersion with respect to g-line light and F-line light, and wherein an angle (θ) to an optical axis of an off-axis principal ray incident on a lens surface of the first negative lens facing the object side at an arbitrary image height y and a focal length (f) of the entire optical system satisfy the following condition: