eh non c est le Sonnar qu il faut regler
reponse du SAV Zeiss :
"Dear Mr. Leseinne,
thanks for your request.
The focus shift is a character of this classical lens design. To get best results with this lens, it was calibrated to minimize focus shift at f/2.8.
If you would like to have no focus shift full open, you can send the lens to us for adjusting.
Therefore, please send the lens (including warranty card and copy of invoice) to us
...."