Dear Rainer, Thierry ans Stefan,
Thank you very much for your analysis , explanation and advice.
I think you are right, my problem has nothing to do with the lens resolution.
I was shooting in the studio with the concrete floor, on a FOBA stand with the new 4,5 m. cable and thought that I covered all bases with that.
Now I realize I was wrong. I will try to tame the system over the weekend with no people in the studio, and I will use different lights. I think that a part of my problem was the small metal plate ( a sort of a spacer, a Sinar part) which I had to install between the camera body and the ballhead. Without that adapter it was impossible to secure the camera on the stand because the H back (different here than eMotion) protrudes to the bottom more. The plate is too small. I will eliminate that with putting the camera in the vertical position without the spacer.
Thank you again,