I can't eloquently put into words how much I love this lens. It performs beautifully on my 5Dmk2 and 7D; it's the kind of lens you just leave on a 5D to bring everywhere. I'm in the middle of shooting a weekend of dance performances right now, for which I rented my other favorite lens the Canon 135 f/2. Both produce just awesome images on my 5Dmk2 at 1600iso f/2.2 1/800 under stage lights. It's good enough I'm probably going to sell my 50 f/1.4 for an 85 f/1.8 because I find I just don't use my 50mm anymore.