Noun
pentaprism (plural pentaprisms)
(photography) A five-sided prism used in the viewfinder of most single-lens reflex cameras
Almost all SLR cameras use a front surfaced mirror in the optical path to direct the light from the lens via a viewing screen and pentaprism to the eyepiece. Source: Internet
The sighting for the device was originally intended to be a cheap pentaprism device, which would allow the user to look down from above and see the sight picture. Source: Internet
Most SLR cameras permit upright and laterally correct viewing through use of a roof pentaprism situated in the optical path between the reflex mirror and viewfinder. Source: Internet
Pentax SLRs are the exception, with a few ancient exceptions, they all feature pentaprism finders and many also include weather sealing. Source: Internet
Technically impossible? ie. take an Sony A7, add a pentaprism, and call it a day. Source: Internet
In 1957, the Asahi Pentax combined the fixed pentaprism and the right-hand thumb wind lever. Source: Internet