Tamron 28mm f/2.8 — first-generation Adaptall wide-angle prime (CW-28), multi-mount fit
Tamron sold the 28mm f/2.8 as model CW-28 under its original Adaptall interchangeable-mount system, introduced in the mid-1970s before the Adaptall-2 revision arrived in 1979. It represented Tamron's standard-speed wide-angle prime of that generation.
As an early Adaptall lens, the CW-28 uses the first-generation adapter interface, offered with mounts including Canon FD, Nikon F, Minolta MD, Olympus OM, Pentax K, Konica AR and the M42 screw thread that was still common on Praktica and Pentax bodies at the time.
A conventional f/2.8 speed and simpler optical formula than Tamron's later CF Macro primes make it a straightforward, unfussy wide-angle rather than a specialist close-focusing lens, prioritising compactness and light weight over extra features.
Being an early Adaptall lens, examples on the used market are older than the more common Adaptall-2 range and worth checking carefully for fungus, haze and aperture-blade oil. First-generation Adaptall adapters do not fit later Adaptall-2 mounts, so confirm which generation a listing includes.