[davidmanze]

Well, it's good to know both flaws (DSLR and mirrorless ones) from the inside. I think, if I had such a problem with a Sigma lens, the dealer/importer would fix it in less than a week - Sigma CH is really quick. I know, that's not helping you.

 

is there some kind of analogy between D500 and D750? Like "if one is +5, the other will be -3"? I found that always strange, of course D850 and D810 have different AFMA on the same lens, but on another lens the difference between both AFMA values is not the same.

 

Now, knowing your DIY skills, the next thing will be you become Mr. Sigma and get the lens back on track? Is there something mechanical one could do? I really don't know, but I guess, not all is firmware based, some things could also be adjusted by hardware?

 

   Funny you should mention that JoJu, I took out the spacer shims behind the bayonet.......thoughts being that the lens would be closer bla bla bla....to no avail......  what happens is the AF just compensates for it....the point didn't move a millimetre!   so, it's all down to where the AF algorithms decide it should stop the lens in relation to what it is seeing from the AF range-finders!

 

   The analogy is difficult to spot, my guess on the D750 it "needs"" +25 (max +5)  and  "gets" +5 on the D500.... knowing that both cameras are well set up it must be more to do with a non compatibility.......that's incomprehensible to all but the chosen few!