Here's a teaser on where I'm starting to take this:
June 11, 2023
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Well, I stuck with the language that I replied to. I don't know what happens with increased input, but I would assume that the two different conversions gains had different asymptotes after they also went non-linear at different levels.
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When you say different levels, do you mean charge levels or voltage levels?
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Outside the pale of course, but the first Foveon (F7) said "Well capacity is approximately 77,000 electrons per photodiode but the usual operating point (for restricted non-linearity) corresponds to about 45,000 electrons"
kronometric.org/phot/sensor/fov/SD9%20sensor%20in%20depth.pdf
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Photon levels.
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Not all, as Jim just said.
On one of my cameras, the ISO setting does not change the raw data at all.
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I was talking about the asymptote value, not the stimulus.
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Then you have the other extreme, like the Canon G9 I have (CCD), which uses analog gain to vary all ISO settings, but there is no visible difference at all. The camera goes from ISO 80 to 1600, but if you expose for 6400 in raw mode at either 80 or 1600, the read noise looks exactly the same. I coined the term, "gain in vain" for this camera. It may as well just use the gain from ISO 80 at all ISOs. Yes, the histogram is very natural and filled at ISO 1600; it's not an arithmetic push. The pre-gain read noise is just so much higher than the post-gain read noise (even at ISO 80) that you can't see the post-gain read noise (which means it probably has little spatial correlation).
