The Tamron 28-200 mm f/ 3.8-5.6 LD Aspherical IF Adaptall-2 model 171A is a universal zoom lens for 35 mm SLR cameras popular in the 1970-90s (via the interchangeable Adaptall-2 mount).
The lens is multicoated.
The optical scheme employs an aspherical element. Focusing is internal.
The Tamron 28-200mm f/3.8-5.6 LD Aspherical IF Adaptall-2 model 171A lens features a plastic body and a rather simple form factor, which negatively characterizes it as compared to the other Tamron Adaptall-2 lenses. Later on such body design has been adopted by Tamron autofocus lenses.