Apparemment, les micro réglages AF seront de la partie.

The EOS 6D does, however offer the same AF microadjust as the 5D Mark III. Adjustments can be made separately for the wide and telephoto ends of zoom lenses, and can also be made per serial-numbered lens (should you have two copies of the same lens that require differing amounts of adjustment).
Source Canon EOS 6D Hands-on Preview: Digital Photography Review