I just got a SIGMA 17-70 1:2:8-4 DC (C) lense. Mount looks very much like Canon EF (S) but it's smaller. Added a foto from a 70-200 EF to compare. Anybody knows what this mount is for? Many thanks in advance
Thanks @Nate S. for his answer.
This looks like the same thing, so yes, SA: https://www.worthpoint.com/worthopedia/sigma-17-70mm-2-4-macro-dc-sigma-sa-1791976047
Solution is Sigma SA Mount