John didn't suggest setting the ISO to less than base ISO except in the example. He certainly didn't suggest setting the ISO to 25. Re-read what he said.
there is no live RGB histogram on my a74. thats the point.
But my field monitor has live RGB wave forms, and i can see what the WB is doing when changing the settings. The a74 has amazing AWB anyway and i can always fine tune in ACR for important photoshoots. other wise i have my white balance very fine tuned for studio work, but i still need to correct colour shifts from using several speed and studio lights.
you want some more evidence. my a74 doesnt have RGB live histogram. but my field monitor has RGB wave forms. i can clip all the colours on the wave form
monitor which is streaming from hdmi. but my incamera histogram still has room to move. so when i set exposure with the camera histogram the wave form monitor has clipped. a good stop
Because we know exactly how this story plays out with you. If you can't see it for yourself using your own equipment and doing your own testing, you simply won't accept as proof what any of the rest of us offer. However, if you give your word now that you will repeat the same test with your A6300 that you used yesterday to "prove" the camera's live luminance histogram matches the raw histogram but this time using a shot dominated by one or more red flowers or similarly vibrantly red subject(s) and include the corresponding raw file and OOC JPEG, then I promise I'll do a similar test using my current working camera (an Oly EM1iii) and, likewise, submit the raw and OOC JPEG here for anyone to view and analyze. Do we have a deal?
Below is a history of the edits you made to your post trying to weazle your way out of what you agreed to. It proves you said "have a deal". People can judge for themselves what you meant.
I re-read this several times because it didn't seem to make any sense but Jim "liked" it, but I still can't make any sense out of it. How do you "underexpose" by using a higher ISO setting with the same exposure that is not strong enough for ETTR at base ISO? You will be further to the right of the ISO setting that you wind up with.
I think a big part of the inefficient communication on such topics stems from the fact that some people are not distinguishing between the empirical phenomena of exposure, ISO settings, and raw files and the personal approaches to risk taking and optimization that people use. Facts vs editorial. Disagreement in editorial seems to some people to be arguments about the empirical facts, but they are not, and need to be kept separate. The empirical facts are fairly simple; much simpler than the range of "strategies".
There really is nothing contradictory about two people who understand the underlying facts choosing different "approaches".
One problem with a lot of discussions is that many people hear "mandate" when someone is describing an option.
I remember when I used to shoot slide film in the '70s; I sent or took the roll to a lab, and if my ISO exposure index did not match the ASA setting, I got dark or bright slides, unsuitable for aesthetic projection. The message is that exposure of digital cameras with raw is very different, and you get to trade off between SNR and headroom, with no need to even think about final image "lightness" because it is not deterministic at shooting time, if you just move some sliders in your converter to normalize lightness.
Less SNR due to less exposure. What is "greater proportion"? It sounds confusing and does not suggest a useful model of noise.
Actually, the more DR in the scene, the more you could benefit from "ISO to the right" with a given exposure, because you may have deeper shadows where read noise is more visible.
This reminds me of my first year law class in contracts. Was there a meeting of the minds? Was the rescission of the acceptance of the offer valid? I'm breaking out in sweat just thinking about it. 😂 Donald realizes that he's cornered, even if he doesn't fully grasp the technical reasons why.