This Vivitar Series 1 28-90mm f/2.8-3.5 lens is available in several mounts, I used it with Minolta XD-11 camera, Minolta MD mount. Fully metallic construction, well made, zooming and focusing are smooth and convenient. You have to refocus when you zoom, but Vivitar claims that because of this better image sharpness is achieved at various focal distances; besides at 28mm you can focus to ~2cm, achieving 1/3 Macro reproduction ratio. This was the first "Vivitar Series One" lens in this zoom range, the series was later extended to 28-105, 28-200mm, the construction became plastic, there are reviews that the image quality in these longer zooms deteriorated as compared to the original 28-90. From my experience 28-90 is already larger range than Vivitar could afford in terms of quality. Vignetting is a very serious issue from 28 to ~60mm unless stopped down to ~ f/8 at 28mm, f/5.6 is enough at 45-60mm. At longer end the lens is soft when wide open, stopping down 2 steps is enough to produce sharp images.