A 35mm film SLR system that added TTL stop-down metering compared to the earlier Mamiya CP system. It consisted of the following models:
- 500 TL - a basic SLR with standard automatic-aperture variation of the M42 screw mount, top shutter speed of 1/500th of a second, TTL spot light metering, match needle system in the viewfinder, without a self timer;
- 1000 TL - a 500 TL with top shutter speed of 1/1000th of a second and a self-timer;
- 500 DTL - a 500 TL with two separate TTL metering systems selected by a switch beside the lens mount: spot for reading just 6% of the total picture and average for full area light measuring;
- 1000 DTL - a 500 DTL with top shutter speed of 1/1000th of a second and a self-timer;
- 2000 DTL - a 1000 DTL in a professional black finish and with top shutter speed of 1/2000th of a second.
Mamiya produced a useful range of Mamiya/Sekor lenses for this system, from the moderate wide-angle 28mm to the super telephoto 400mm. Most of them had automatic diaphragm, and only the 60/2.8 Macro and 400/6.3 were equipped with preset diaphragms. Lenses designed for the TL series cameras had a silver diaphragm ring and a silver front rim; it was just a fashion element of the time that was not unique to Mamiya lenses. Later DTL series lenses were all black.