breech-lock mount

The Petri Flex 7 is a single lens reflex camera introduced by Petri in 1964 and is claimed to be the world’s first SLR with a fully integrated cadmium sulfide light meter. Known by many as “the poor man’s Contarex” for its superficial (and most likely intentional) resemblance to the Zeiss Ikon Contarex “Bullseye”, the Flex 7 was marketed as Petri’s flagship model and was supposedly meant to compete with the nigh untouchable Nikon F. Advertisements put special emphasis on the camera’s auto-indexing feature (meaning that the lens’s aperture setting would be automatically relayed to the body), the fact that its integrated light meter had an in-viewfinder indicator, and how Petri’s mastery of mass production meant high quality cameras at low prices.