« on: December 04, 2012, 04:35:13 PM »
What I found I had to do: With the 40mm (the only microadjusted lens, in my case) on the camera, I turn AFMA to "Disable." (As far as I know, you do not lose registered AFMA values by doing so.) Then I take a shot with the 40mm and the new setting (disabled AFMA) before turning off the camera and switching to the 300mm+TC.
Taking this extra shot with AFMA disabled seems to be the key. I also tested some more, taking a shot with a lens having +0 adjustment is not enough, you have to set AFMA to Disable. Doing this doesn't lose the registered values.
Now I feel lucky that my tele and macro lenses are fine with +0 .