Auto Tamron 28mm f2.8 (Adaptamatic)
This is a somewhat rare lens these days. The adaptamatic mount was abandoned in favor of the adaptall mount. It was in production for only four years. My copy has an M42 mount. It handles well on the T2i. It is very well built. Focus dampening is perfect. The only issue I had was inconsistent exposure in aperture priority mode. Usually the T2i overexposes at f5.6 & up when I use adapters. With this lens the T2i gradually overexposes from 3.5 up.
It is soft at f2.8 with noticeable vignetting. At f4 it tightens up. At f5.6 it is tack sharp.
Contrast is a bit low thru the entire range of f stops. Shadow detail is excellent.
Colors are a bit muted but accurate.
It lacks BBAR coating but it handles fringing and flare well. Use a lens hood at all times to preserve contrast.
Bokeh is not very smooth but it is consistent and not too distracting.