Hey guys -
I've been using my Sigma 70-200 2.8 (newest one non-OS) with the Canon 7D for half a year and have mixed results. I shot a basketball game last night and it seems like the 7D was back focusing on the long end. I had sent the lens in to Sigma to fix this and it seemed okay upon arrival. I've shot with it extensively since and the problem only comes up in Al Servo mode. The focus is sharp on One Shot. To be sure it wasn't the lens, I switched it to my 1D2 and the results were immediately better. I shot AF expansion on the 7D, have tracking set to slow - what am I doing wrong? Should I only use center AF point? Any suggestions would be greatly appreciated.