The Pentax and its later development and likewise classic 1964 Pentax Spotmatic allowed Asahi Optical Company to develop into a photographic multinational company, eventually leading the company to rename itself "Pentax" after its seminal product.
The Asahi Pentax of 1957 featured:
Moreover, the Pentax placed controls in locations that would become standard on 35 mm SLRs from all manufacturers, such as the right-handed rapid wind lever, the bottom right mounted rewind release, and film speed reminder around the film rewind crank, a location that remained standard even when the dial went from being merely a reminder to the photographer to actually controlling the light-meter built into later SLRs.
The Pentax offered these features at a relatively low price, introducing many photographers to 35 mm SLR photography.
The Pentax became so dominant that the 42 mm screw lens mount used on the Pentax and Pentax Spotmatic become known as the "Pentax universal screw mount" although it had actually been introduced by Contax in 1949. Previously most makes of camera used proprietary mounts; the use of this mount by other manufacturers allowed owners of M42-equipped cameras to mount lenses from Zeiss, Yashica, Soligor, Vivitar, Topcon, Sigma, Chinon, and many more as well as Asahi's own highly regarded Takumar lenses. These lenses had no other communication with the camera than a diaphragm interface which allowed focussing at full aperture, the lens being stopped down to working aperture on pressing the shutter release. Later cameras required more lens-body communication to implement shutter priority exposure, program auto exposure, and finally, autofocussing, and different manufacturers used different interfaces, ending the era of interoperability. In 1975 Pentax introduced the k mount to replace the 42 mm screw lens mount used so successfully until then. Its design has been upgraded so carefully over the years the the lates 2008 models, Pentax K20D and Pentax K200D are the only digital cameras that can used any previously available lens for film.