I just picked up my Sigma 50... and the fast answer is... wow! A lot of Canon people are getting issues with proper focus on their units and the odd Nikon, but I swear, I must have a horse shoe up somewhere, because mine is incredible out of the box. Like every new lens, it takes some getting used to before getting the best out of it, especially watching the focus points and razor thin DOF at F/1.4. I think that this is a prime that I am going to enjoy playing with! Oh... I cannot recall who off the top of my head, but someone wanted me to do a few specific kinds of tests with it. Now is the time to ask.