Just a quick question. I have an old Meyer-Optik 58 f/1.9, M42 screwmount lens that I was just testing on my 5D, since I wanted to see what kind of effects I could get with its 14-blade diaphragm. Anyways, I noticed that even tho the shot was focused and looked sharp in the viewfinder, the RAW files didn't really look that sharp until the lens was stopped down to f/8 or f/11. Slightly curious, I then took three more shots at f/4 - one where the lens was focused so the shot looked good in the eyepiece and then two more, with the lens focused slightly in front of and slightly behind the main object in the shot. And you know what? The shot with the lens focused slightly behind came out very sharp. So, I'm wondering if this is just an issue with the lens - perhaps it needs to be serviced so the focus is accurate? Or, is this just a side effect of mounting an M42 lens on a Canon 5D?