Tamron SP 60-300mm f/3.8-5.4 — Adaptall-2 telephoto superzoom (23A), long production run
Tamron's SP 60-300mm f/3.8-5.4 launched in 1983 as model 23A within the premium SP line of the Adaptall-2 system, and remained in production remarkably long, reportedly into the early 2000s, well after most Adaptall-2 lenses had been discontinued.
As an SP-branded lens, the 23A received Tamron's better multi-coating and build quality of the era, covering a wide 5x zoom range from short telephoto to super-telephoto with a variable f/3.8-5.4 aperture. It uses the Adaptall-2 mount, available with adapters for Canon FD, Nikon F, Minolta MD, Olympus OM, Pentax K, Konica AR, Contax/Yashica and M42.
The unusually broad range for a single lens made it popular with photographers wanting one telephoto to cover portraits through distant subjects without changing lenses, at the cost of a slower and narrower maximum aperture at the long end than dedicated telephoto primes.
Its long production run means both older and newer-condition examples appear on the used market. Check the extending zoom barrel for wear and looseness, confirm smooth aperture operation across the range, and verify which mount adapter is included, since Tamron updated the Adaptall-2 adapter design over the lens's lifespan.