ok sorry for the unprecise question
at the end what we are searching for is a way to render out hdri images like. with the high range.
then you produce hdri images with a cam,you take more images with different fstops and put them together into one single file (at least this is the way i understand this). and we’re on the search to render out such images, just to have more possibilities in compositing.
i know that the guys at weta render out floating point ( i spoke to the guy who did the lighting on many gollum shots for two towers a few days ago), so there must be a way.