Viewfinder mask orienting device in a camera

Claim 1

In a photographic camera having a viewfinder optical system with a square or substantially square focusing screen and a film holder mounted rotatably about the optical axis of the camera to change the orientation of an oblong optical image of a photographed object projected on its film, the combination therewith of a viewfinder mask orienting device comprising: a base plate disposed in said viewfinder optical system and supporting said focusing screen in optical axial alignment with said optical system on that side of said base plate affording greater facility in interchanging of said focusing screen; two Y-shaped levers each having two angularly disposed blade arms and one short arm, said levers being pivotally supported at their junctures of said three arms on said base plate near diagonally opposite corners of said focusing screen, each of said Y-shaped levers being pivotable between a first position at which one of the angularly disposed blade arms masks the edge part of its associated side of said focusing screen and a second position at which the other blade arm masks the edge part of its associated side of said focusing screen, one of the opposing blade arms of said Y-shaped levers masking one pair of opposed sides of said focusing screen at the same time in said first position, the other of said opposing blade arms of said Y-shaped levers masking the other pair of opposed sides of said focusing screen at the same time in said second position, said Y-shaped levers being disposed for cooperation to alternately mask edge parts of the two pairs of opposed sides of said focusing screen thereby to form an oblong viewfinder image of the object and change the orientation of the same image to conform to that of the image on the film; and transmission means interposed between said film holder and said short arms of said Y-shaped levers so as to be actuated by the rotation of said film holder to thus operate said Y-shaped levers.