I think it should be CONF_SWAPSIZE
AFAIK CONF_SWAPFILE is for the swap location

Probably I have found the reason: this seems to happen only when using raspstill -t 1. Now I left the default time delay and image qualities are the sames. Strange anyway, I would have expected the quality to be indipendent from --rot. Concerning the question from Jamesh: --rot 90 and 270 were less ...

Since I had to mount the camera upside down, I have to use raspistill -rot 180 . I was quite disappointed with the image quality (too dark), until I realised that this darkness was caused by the rotation itself. After trying unsucessfully to make it lighter by playing with --brightness and --iso, I ...