Patent ID: 7440196
Filing Date: 2008-10-21
Classification: G02B

Abstract:
1. An image forming optical system comprising, in order from an object side: a first lens unit having a positive refractive power; an aperture stop; and a second lens unit having a positive refractive power, the first lens unit being a lens unit which is closest to the object side in the image forming optical system; the second lens unit being a lens unit which is closest to an image side in the image forming optical system, the second lens unit comprising, in order from the object side: the image forming optical system satisfying the following conditions (1) and (2): wherein R 2 denotes a paraxial radius of curvature of the surface of the front lens unit closest to the image side, R 3 denotes a paraxial radius of curvature of the surface of the rear lens unit closest to the object side, ΣD 2 G denotes an axial length from the surface closest to the object side to the surface closest to the image side in the second lens unit, and FL denotes a focal length of the image forming optical system.