I've just begun my test of the Tamron 27A. It is Tamron's successor to the legendary 35-80mm f2.8-3.8 01A. They are often compared which may be a bit unfair to the 27A. I am fortunate to have a nice copy of this lens. My Adaptall to Eos adapter has a little play in it. Focus dampening is light but positive. Aperture clicks nicely with 1/2 stops thru f32. The zoom ring is a tad thin for my taste but it works smoothly. From what I've seen so far this lens is very sharp. It is a tad soft wide open but it is razor sharp at f5.6. Macro mode is very easy to use. From 35-80mm the lens focuses down to14 inches. Performance in macro mode is excellent. There is some vignetting wide open. The lens will also fringe in high contrast backlight. In high contrast side lighting it does not show any fringing. Bokeh is a bit busy at f5.6 and up. Bokeh fringing is well controlled at 28mm f5.6, but bokeh fringing at 50mm and 80mm is quite noticeable. Distortion is not noticeable. Color rendition is spot on. Colors are accurate and nicely saturated. Shadow detail is excellent. This lens is a keeper for me. It is sharp and versatile.