I own a 50mm f/1.4. AF is accurate, but not always consistent. In other words, 6-7 times out of 10 it will be spot on. Those other 3-4 times will be a crapshoot, though. Just something to think about. It's a sharp lens and well worth the ~$400USD, though. You'll find a lot posters on here that hate on that lens, but it's quite good, especially for the money. I've heard others making the jump from the f/1.8 II to the f/1.4, and for the most part they've had good things to say about making the switch.