Well, we could talk about this for hours: this is one of the most controversial, irritating, and spectacular lenses in the lineup. I won’t pretend to know what you’ll think of it, but our customers are evenly divided with “I love it” and “I hate it.” Here are a couple of pointers:

• If you’re not used to working with very narrow depth of field (f/1.2 close up is NARROW) this lens will take some practice. Use one autofocus point only or it will focus where it pleases, not where you want.
• The plane of focus is not flat; it’s slightly curved. Focus-recomposing will guarantee you an out of focus shot. Just don’t do it.
• The 50 f/1.2 L exhibits focus-shift for near distance shots, meaning that shooting objects a few feet away between f/2 and f/4 the lens will probably not autofocus accurately. At f/1.2 it’s accurate, and by f/5.6 the depth of field is wide enough that you won’t see the effect.
• The 50 f/1.2 L is camera specific: a copy that is wonderful on one camera may backfocus on another. It’s best used, for that reason, on cameras with focus adjustment like the 1D series or the 5D mkIII. If you don’t use autofocus adjustment, your images are likely going to be back or front focused.

The bottom line: when this lens is right, the shots are spectacular and the background blur is awesome, just like the 85 f/1.2. But it’s more finicky and more difficult to get those shots with this lens.
March, 2013