Patent ID: 8427762
Filing Date: 2013-04-23
Classification: G02B

Abstract:
1. An optical system comprising, in order from an object side to an image side: a first lens unit having a positive refractive power; an aperture stop; and a rear lens group, wherein the rear lens group includes a second lens unit configured to move during focusing, wherein the first lens unit includes n positive lenses (n is an integer greater than 1) and one or more negative lenses, and wherein, when i (i is an integer equal to or greater than 1) is an order of an optical member counted from the object side to the image side, Ndi and νdi are respectively a refractive index and an Abbe number of a material of an i-th positive lens of the first lens unit with respect to d-line light, max(νdi) and min (νdi) are respectively maximum and minimum values of the Abbe number νdi, min(Ndi) is a minimum value of the refractive index Ndi, fp is a focal length of the first lens unit, and f is a focal length of the entire optical system, the following conditions are satisfied: