lgrobe

Hi, I am a bit confused. I just bought one as a cs-mount lens on ebay: https://www.ebay.de/itm/Fujinon-1-4mm-f-1-8-Fisheye-lens-CS-Mount-DF1-4HB-L1-Ideal-for-All-Sky-Camera/123866962892?hash=item1cd70bdbcc:g:HAkAAOSwDuZdSr43 I have a ZWO ASI 120mm. Since the camera is sold with a CS lens (150° fisheye), I hoped to be able to simply replace it. Yet I did not manage to get a sharp image out of this combination. The problem may be that I am not able to screw it deep enough into the M41 to C-mount adapter shipped with the camera - the threaded part of the lens is not very long, and the ZWO adapter is 7mm thick. How did others attach this lens to the ASI 120mm? Best, Lars.