Please note, that only one value of 4 is used (so camera effectively 12 bit at this ISO).
With such high noise (screenshot #1, see histogram bell width) difference in one 'real' level is very hard to see in practice (and I do not see any visible difference between automatic black level and manual set to 2047 or 2048).
Thank you for the sample (I've checked only EOS cameras, will inspect G9X2 in more depth).
Here is histogram of masked pixels: https://www.dropbox.com/s/06nyv7dhu56n4i1/Screenshot%202017-03-25%2022.4...
(black subtraction turned off).
And here is the same histogram, but zoomed in: https://www.dropbox.com/s/d1grqdcl343tncj/Screenshot%202017-03-25%2022.5...
Please note, that only one value of 4 is used (so camera effectively 12 bit at this ISO).
With such high noise (screenshot #1, see histogram bell width) difference in one 'real' level is very hard to see in practice (and I do not see any visible difference between automatic black level and manual set to 2047 or 2048).