The Mamiya/Sekor 500 TL and 1000 TL, introduced in October 1966, were fully mechanical 35mm SLR cameras with M42 screw mount. The numerals represented the highest shutter speed (1/500 or 1/1000 sec.), and the letters "TL" signified Through-the-Lens spot light metering.
The Mamiya/Sekor 500 DTL and 1000 DTL, introduced in July 1968, offered choice of two exposure metering systems - the spot metering for limited area light measuring and the average metering for full area light measuring. Mamiya also introduced a black-bodied 2000 DTL in 1969.
Auto and preset Mamiya/Sekor lenses were part of the system.