Tamron's Adaptall system released in 1973 and allowed the company to make one lens for all popular mounts. Instead of designing specific versions for each lens mount, Tamron designed one lens and a series of adapters that fit all types of cameras. Automatic aperture and metering were possible with the first version, and the later Adaptall-2 made it possible for maximum aperture data to be transmitted as well. Both versions can be used interchangeably.
Adapters exist to mount Adaptall lenses to most modern systems, although some of them cannot communicate aperture information.