The Spotmatic cameras were introduced by Asahi Optical Company in 1964 and marketed through 1976. The camera was one of the first commercially available 35mm SLRs to include through-the-lens metering. The camera name is derived from the use of spot metering on the original design of the camera. The metering system was changed to average metering prior to its release but the change happened too late to change the marketing materials, so the original name continued to be used. A series of different models were made with minor changes and improvements. All Spotmatics use the M42 lens mount. In the United States, Spotmatic cameras were imported and marketed by Honeywell and bear the name "Honeywell Spotmatic". Cameras manufactured for sale outside the US were badged "Asahi Spotmatic".
The Spotmatic SP
The Spotmatic SP was introduced by Asahi Optical Company in 1964, and was one of the first 35mm SLR cameras 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. Mercury batteries are now banned but Zinc-Air batteries can 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 batteries. 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 center a needle on the right edge of the viewfinder. The body took lenses with an M42 screw thread, providing a large range of available lenses. The system became the workhorse of many professionals of the period. Three variants of the Spotmatic SP are common: 1) Black and chrome body with Asahi Pentax badge on prism housing, Spotmatic badge on front below shutter release and SP badge on top near the rewide knob. 2) All black body with Asahi Pentax badge on prism housing, Spotmatic badge on front below shutter release and SPbadge on top near the rewind knob. 3) Blank and chrome body with Honeywell Pentax badge on prism housing and Spotmatic badge on front below shutter release (but no correspond SPbadge). The Spotmatic SP did not have a hotshoe.
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 second, flash sync 1/60 second
Metering: CdS TTL metering (stopped-down manual match-needle metering system) EV 1.7 ~ 18 (ISO 100) ASA range 20-1600 (on original Spotmatic)