Real-image finder optical system

Abstract

A real-image finder optical system includes a positive objective optical system, an erecting optical system, and a positive eyepiece optical system, thereby an object image, which is formed by the objective optical system, and is upside down and reversed from left to right, is reinverted by the erecting optical system to the proper orientation. The erecting optical system includes a plurality of reflection surfaces, at least one of which is provided along an optical path on the object side with respect to the position where the object image is formed, and at least another of which is provided along an optical path on the eyepiece side with respect to the position where the object image is formed. The eyepiece optical system includes a positive lens element having a transverse magnification of more than 1.0 provided between the object image (finder image) and the reflection surface provided on the eyepiece side with respect to the position where the object image is formed.

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 objective optical system comprises a negative lens element which has a transverse magnification of more than 1.0, and is provided on the object side with respect to a position where said object image is formed; and    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 said negative lens element, 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.    
   
   
       2 . 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 objective optical system comprises a negative lens element which has a transverse magnification of more than 1.0, and is provided on the object side with respect to a position where said object image is formed; and    wherein said erecting optical system comprises a plurality of reflection surfaces, at least one of which is provided along an optical path between said position where said object image is formed and said negative lens element, 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.    
   
   
       3 . 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 objective optical system comprises a negative lens element which has a transverse magnification of more than 1.0, and is provided on the object side with respect to a position where said object image is formed; and    wherein said erecting optical system comprises two reflection surfaces that are provided along an optical path on the object side with respect to said negative lens element, and wherein said two reflection surfaces comprise a roof reflection surface.    
   
   
       4 . 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 objective optical system comprises a negative lens element which has a transverse magnification of more than 1.0, and is provided on the object side with respect to a position where said object image is formed; and    wherein said erecting optical system comprises two reflection surfaces that are provided along an optical path between said negative lens element and said position where said object image is formed, and said two reflection surfaces comprise a roof reflection surface.