I was fooling around in the yard today using the T3i and my Russian Jupiter 37A 135mm f/3.5 lens. It's in Pentax Screwmount (M42), easily adapted to Canon SLRs. The Jupiter 37A was set at f/5.6. I used Live View and the T3i's sweet tiltable screen. Pretty sharp, yes? I will admit to some mild sharpening during processing, but believe me, it takes a sharp image to make a sharp image.