Where can I find a good tutorial on how to perform a micro adjust for my lenses? I looked around a little on this forum without success. I have a 50D and 4 lenses; 10-22, 85 f/1.8, 24-105 f/4, and a 70-200 f/4 IS. 'd like to get the most accurate focusing possible, especially when using the 70-200at the MFD.