Patent ID: 8773783
Filing Date: 2014-07-08
Classification: G02B,H04N

Abstract:
1. An optical system comprising, in order from an object side to an image side, a front unit having a positive refractive power, an aperture diaphragm, and a rear unit, wherein the front unit includes a first lens unit having a positive refractive power, the rear unit includes a second lens unit adjacent to the aperture diaphragm and configured to move in focusing, and the first lens unit includes n (which is an integer equal to or larger than 2) positive lenses and one or more negative lenses, wherein materials of at least two positive lenses of the n positive lenses in the first lens unit satisfy the following conditional expression: where ΔθgF is an abnormal partial dispersion of each material, wherein the material of one or more positive lenses of the n positive lenses in the first lens unit satisfies the following conditional expression: wherein the following conditional expressions are satisfied: where Rp denotes a radius of curvature of a refractive surface that is concave and closest to an image in the first lens unit, Rn denotes a radius of curvature of a refractive surface that is concave and closest to an object in the second lens unit, and ftotal is a focal length of an entire optical system.