Patent ID: 7508599
Filing Date: 2009-03-24
Classification: G02B

Abstract:
1. An optical system comprising: a plurality of lens elements having respective lens surfaces; and an optical member including an interference film formed on one of the lens surfaces of the lens elements; the optical system including a negative lens group and a positive lens group adjacent to the negative lens group; the positive lens group including a positive lens element located most toward the object side of the positive lens group; and the optical member being formed on the image side surface of the positive lens element; wherein the following conditional expressions are satisfied: 0<|Φ/R|<0.6 0°≦|B|<13° where Φ denotes the effective diameter of the lens surface, R denotes the radius of curvature of the lens surface, and B denotes an angle of the principal ray passing through the lens surface relative to the optical axis at the lens surface in the air side.