Selective mode angle finder for SLR camera

Claim 1

A selective mode viewfinder attachment for a single lens reflex camera, comprising: (a) a bent cylindrical housing member having an L-shaped cross-section and open at both ends, (b) a mirror disposed in the housing member to define an optical axis therethrough from one end to the other having an angular bend of approximately 90°, (c) a telescopic optical system disposed in the housing member in alignment with the optical axis, (d) a cylinder member rotatably mounted in the housing member about an axis parallel to but offset from the optical axis, said cylinder member including a solid portion selectively alignable with the optical axis of the attachment to thereby block any reverse incident light from entering the viewfinder eyepiece, (e) a pair of spaced passages defined in the cylinder member and extending longitudinally therethrough parallel to the cylinder axis and radially spaced therefrom a distance equal to the offset distance between the cylinder axis and the optical axis, (f) magnifying lens means disposed in one of the passages, and (g) means for attaching one end of the housing member to the viewfinder eyepiece of an SLR camera in alignment with the optical axis thereof, whereby picture composition and accurate focusing may be implemented by rotating the cylinder member to align a selected one of the passages with the optical axis of the attachment.