Tamron SP 28-135mm f/4-4.5 — Adaptall-2 general-purpose zoom (28A), multi-mount fit
Tamron's SP 28-135mm f/4-4.5 launched in 1983 as model 28A, part of the premium SP range within the Adaptall-2 system, and remained available until 1988. It offered a wide-to-short-telephoto range in a single lens aimed at photographers wanting fewer lens changes.
As an SP lens, the 28A benefited from Tamron's higher-grade coatings and build of the period, spanning wide-angle to short telephoto with a modest variable aperture. It uses the Adaptall-2 mount system, with adapters available for Canon FD, Nikon F, Minolta MD, Olympus OM, Pentax K, Konica AR, Contax/Yashica and M42.
The nearly 5x range made it an unusually versatile single-lens option for its time, predating the affordable general-purpose superzooms that became common in the following decade, though wide-open sharpness and vignetting at 28mm reflect the compromises of covering such a broad range.
SP-branded Adaptall-2 zooms like this tend to hold slightly more value than Tamron's standard-line equivalents. Check the zoom ring for smooth, even travel across the full range, confirm the aperture blades move freely without oil, and verify the mount adapter supplied is a genuine Adaptall-2 unit.