Asahi Pentax SP

The Spotmatic was introduced by Asahi in 1964 and was the first camera to sell well with Through-the-Lens light metering. The camera was entirely mechanical apart from the light meter, which was powered by a 1.35 volt PX400 mercury cell[1]. A small switch on the (photographer's) left side of the lens housing was pushed up to stop down the lens and activate the meter; the exposure controls would then be adjusted to centre a needle on the right edge of the viewfinder. The body took lenses with a 42mm Pentax/Praktica screw thread, giving a huge range of alternatives. The system became the workhorse of many professionals of the period. Spotmatic SP top plate ↑ Mercury batteries are now banned; "Zinc-Air" cells can now be used instead, or it is possible to carry out a minor modification to the meter circuit to allow the use of 1.55 volt 387S silver-oxide cells. Type: SLR body Manufacturer: Asahi Optical Co. Year of launch: 1964 Films: 35mm, speeds up to 1600 ASA Viewfinder: pentaprism eye-level viewfinder Lens Mount: Pentax/Praktica screwmount (M42) Shutter: Focal plane shutter, speeds 1 - 1/1000 sec. Metering: CdS TTL metering (stopped-down manual match-needle metering system) EV 1.7 ~ 18 (ISO 100) ASA range 20-1600 (on original Spotmatic) The Spotmatic was introduced by Asahi in 1964 and was the first camera to sell well with Through-the-Lens light metering. The camera was entirely mechanical apart from the light meter, which was powered by a 1.35 volt PX400 mercury cell[1]. A small switch on the (photographer's) left side of the lens housing was pushed up to stop down the lens and activate the meter; the exposure controls would then be adjusted to centre a needle on the right edge of the viewfinder. The body took lenses with a 42mm Pentax/Praktica screw thread, giving a huge range of alternatives. The system became the workhorse of many professionals of the period.