Patent ID: 6862411
Filing Date: 2005-03-01
Classification: G02B

Abstract:
1. A real image mode finder optical system comprising, in order from an object side: an objective optical system with a positive refracting power; a field frame located in the proximity of an imaging position of said objective optical system; and an eyepiece optical system with a positive refracting power, wherein said objective optical system has image erecting means including four reflecting surfaces, and wherein a focal length of said objective optical system is variable, and when a magnification of said finder optical system is changed, at least two lens units are moved along different paths and a focal length of said objective optical system at a wide-angle position thereof is shorter than a focal length of said eyepiece optical system, said real image mode finder optical system satisfying the following condition:  where mh is a maximum width of said field frame and fe is a focal length of said eyepiece optical system.