Id be interested to hear from anyone who check columation between different mounts. We are fining that you can change a mount and replace the same mount and it goes back with near exact same columation, I don't have figures for this. We are finding that different mounts do need change of back focus though. i.e. PL to Canon or Allstar. We are very careful with our camera columation set up and regularly check it, I don't know how frequently other users check columation on cameras.