A system consisting of fully mechanical 35mm SLR cameras with TTL exposure metering and an extensive line of M42 screw mount lenses, from ultra wide angle to super telephoto. The first two cameras in the system - Singlex TLS (1967) and TLS 401 (1970) - provided stop down metering, the latter also allowed to choose either spot or average metering. The SLX 500 (1975) is a stripped-down version of the Singlex TLS with a shutter speed range of 1/30 - 1/500 sec. The Singlex II (1976) is similar to the Singlex TLS, but the shutter speed dial is located on the top of the camera body. The Auto TLS EE (1976) added full aperture exposure metering and shutter-priority automatic exposure metering with Rikenon EE (Electric-Eye) lenses.