Also I should answer a question I have received many times-sorry I was not able to reply to individual emails.

Q: I MA my zoom lens it works great at long focal length but it looks off at the wide end, what is wrong?
A: Current Canon firmware only stores a single value for a zoom lens. The focus shift changes with the focal length, so unfortunately there is no way around this. Good news is 1DX can store different MA values for different focal lengths of a zoom lens. Maybe the Goddess of EOS will decide to provide this feature to other cameras via future firmware updates.