Patent ID: 6867917
Filing Date: 2005-03-15
Classification: G02B

Abstract:
1. A real-image finder optical system comprising a positive objective optical system, an erecting optical system, and a positive eyepiece optical system; wherein an object image, which is formed by said objective optical system, and is upside down and reversed from left to right, is reinverted by said erecting optical system to the proper orientation; wherein said erecting optical system comprises a plurality of reflection surfaces, at least one of which is provided along an optical path on the object side with respect to a position where said object image is formed, and at least another of which is provided along an optical path on the eyepiece side with respect to said position where said object image is formed; wherein said eyepiece optical system comprises a positive lens element; wherein said positive lens element is provided between said position where said object image is formed and said reflection surface provided along said optical path on the eyepiece side with respect to said position where said object image is formed; and wherein said positive lens element satisfies the following condition: wherein mp designates the transverse magnification of the positive lens element; and wherein said real-image finder optical system satisfies the following condition: wherein fp designates the focal length of said positive lens element; and feL designates the focal length of the optical system, excluding said positive lens element, on the eyepiece side with respect to said positive lens element.