So I've had my 50mm 1.2 lens for about a year now and went on a mission trip to the Philippines. I noticed during the second week while I was there, my lens would occasionally get stuck while using the AF. When I would AF on a subject close, it would be fine, but when I would AF on something far, it would get stuck! I would then have to move the ring manually to get it to work again. I don't know if it had something to do with the humidity, because when i got back to the states, the lens performed fine! Anyone experience something similar to this? I'm thinking of sending it to canon... how much would it cost to repair?