Have been looking for advice on a couple of FF cameras for astro-imaging. I enjoyed using a modified Canon 6D but have been very keen on the Nikon line. I tried out a temp loaner D750 with a stock 80-200mm F4.5-5.6 Nikon lens and also a few shots prime focus on a Vixen ed103s both with no filters. As expected I noticed the FF vignetting in each case which was probably a hair more than expected in comparison to the 6D. Also I am in an Orange to Yellow sky zone so there was that to contend with. What I did notice was that when pre processing with PI or DSS and then initially using STF and ABE, I would see what was seen in Vostock's image noted in the link below. Ironically enough it was in that same region of sky. It could be mostly processed out but it was a real pain.
Vostock's image with the circular color artifacts:.
I did some reading and came across more info that seemed very applicable and the root of what I want to know about some particular camera responses.
Details provided by Wei Hao in the section discussing non-linearity response (and images) with the
D800 (no FW hack and D810a:
All that said, I am wondering just what the non-linearity level exists with the D750 and how it would compare to the D800 w/FW hack modified or unmodified and the Canon 6D? Even an unofficial estimation seen from initial processing of data would be worth knowing. I hope Wei Hao might chime in on this. I know he said in a different post that he recommended a 6D or (I think) the mod'd D800 w/FW hack, verson for someone but not specifically relating to the non-linearity issue. And I agree that if you don't have to deal with this from the beginning, it makes for much easier post processing hassles.
Edited by skyler, 24 May 2018 - 11:38 AM.