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.
With the exception of 50, 55 and 60mm lenses, the rest of the Mamiya/Sekor lenses of this system are suspiciously similar to Tokina models made in the mid-1960s - mid-1970s. But even the 50, 55 and 60mm lenses may not have been Mamiya's own developments, but optical designs licensed from Tomioka.