I know you can make the individual AF adjustments (for back and/or front focus) for AF lenses made my Pentax, and Pentax only.
My Sigma 24-60 needed an adjustment for front focus and now it is just fine (most likely it presents itself as a Pentax lens, I don't know; but it works). However, there seems to be no way to adjust my two other Sigmas as they are recognized as the "same" lens (that is 24-60mm). Unfortunately, the adjustment needed by the 24-60mm is just the opposite of the other two. When I mount them they start front focusing heavily due to the prior dedicated AF adjustment.
1) Does this mean simply that I can use only one of my Sigma lenses on my K20D?
I also have a K10D body which allows for global AF adjustment (and it needed that to correct consistent back focus with every lens). That adjustment works only to some extent (as long as all the lenses need the same/similar value).
2) Is there a way (as yet undocumented & undisclosed!) to make "individual" AF adjustments on the K10D? If yes, then I can use one of my other Sigmas on it...
I guess the answers are 1-Yes and 2-No.
Still, there is no harm asking