I used kStars 3.5.2 + Ekos on an astroberry for the first time a while ago. I configured the indi_Nikon driver to transfer raws (it's a Nikon D500).
The pictures open up then in fitsviewer, but the histogram x-axis only did displayed a scale from 0..255, so eight bit. I was expecting at least 12 bit.
So
a) What's the recommended setting for transfer with DLSRs, .fits? Does this even influence the transfer off of the camera in any way or is this a indi server - indi client thing? The NEFs get stored on the astroberry, probably using the gphoto2 library.
b) How does the fitsviewer handle the conversion nef -> fits?
c) Do I need to upgrade libraw or install a specific lib for Nikon NEFs?
The default histogram is non-linear 8bit. So that's normal. You can go to Settings --> Configure KStars --> FITS to turn off non-linear histogram. If you're shooting with DSLR, best is to keep them as native all the way.
"If you're shooting with DSLR, best is to keep them as native all the way. "
Unless I'm miss-understanding what you said, this is new information for me. I was under the impression that I would get more useful info (e.g. the solved position, filters, etc) if I saved my images as fits files from the start as EKOS captures them from my Nikon Z7 (attached to a scope).