MFA says +3?

Q. Am I right that means the 40 mm pancake is front focusing?

As I understand it ; a positive MFA number means it will shift the focus point further away behind the standard auto focus point.

Looks like the two L lenses are smack on zero.

All assuming using the dot tune method my first zero shot was in focus.

I am a bit unsure of one aspect of the Dot Tune method.
Should your first AF try just be left at zero, to calculate the in focus values positive and negative, and then calculate the mid point. And set that as the MFA amount.

I need to carefully review all the respective images before saying whether it works for me.

I always felt the two L lenses were extremely accurate,and the 40mm very good. But then a suppose +3 is not a lot.

Yes.

+3 is not a lot, especially at f2.8 and even more especially at 40mm. I'd say it makes a difference on my 135 @f2 at portrait distances.

Using Magic Lantern's Auto Dot Tune on my Sigma 24-70, I kept getting inconsistent results - once as much as +45 and other times in the 20s; 28, 24, 21. Then I saw a post here saying to do it in strong sunlight, so I set up outside and at 70 mm got three results at +11 and at 24 mm three times +12. So +11 is the magic number (long end is more critical) and it has changed the lens dramatically.

tzalman wrote in post #16637574
Using Magic Lantern's Auto Dot Tune on my Sigma 24-70, I kept getting inconsistent results - once as much as +45 and other times in the 20s; 28, 24, 21. Then I saw a post here saying to do it in strong sunlight, so I set up outside and at 70 mm got three results at +11 and at 24 mm three times +12. So +11 is the magic number (long end is more critical) and it has changed the lens dramatically.

I used a 600 watt video light to illuminate my target. Not sure if that mattered or was a good thing.

Submariner wrote in post #16636204
All assuming using the dot tune method my first zero shot was in focus.

I am a bit unsure of one aspect of the Dot Tune method.
Should your first AF try just be left at zero, to calculate the in focus values positive and negative, and then calculate the mid point. And set that as the MFA amount.

Maybe I'm misreading this bit - but no your reference focus should not be set using PDAF (through the lens phase detect auto focus).
Use live view on x10mag to AF (and refine using manual focus if need be) to set your reference focus.
Then turn LV off and proceed with the dot tune method to determine near / far confirmation points.

TerminalCity wrote in post #16640010
Maybe I'm misreading this bit - but no your reference focus should not be set using PDAF (through the lens phase detect auto focus).
Use live view on x10mag to AF (and refine using manual focus if need be) to set your reference focus.
Then turn LV off and proceed with the dot tune method to determine near / far confirmation points.

Thanks for the clarification I actually did it that way - more by accident than design. Other than I accepted the 10x AF in Live View because it seemed spot on. So just didn't refine the aUto AF with a Manual fine tune.