How to get the best raw exposure, part 2

That's the problem. Clear thinking depends on denoting different concepts with different words. I'm not 'an expert on the correct terminology' - I just know that if you muddle words and the words 'all mean the same thing to you' you'll never think clearly - simply because you're muddling different concepts and think that different things are all the same.

This isn't 'physics and engineering language'. It's photographic language. Terms like 'exposure' and 'lightness; come from the vocabulary of photography. Most physicists and engineers who are not photographers wouldn't be familiar with them. There are plenty of glossaries, most threads like tis the definitions get given, disputed, argued about. The base problem these days is that most of the information resources from which photographers learn get the basics wrong.

I'm just pointing out how confusing the terminology confuses thinking. Being 'tolerant' of confused terminology doesn't help clear up the confused thinking.

Which 'ETTR' do you mean?

Well, if you thought that 'ETTR' is 'correct', then that's a given that anything less is 'under', isn't it? Still I would say that ETTR is a means to an end, not an end in itself. Most ETTR techniques I have seen will not maximise exposure - if maximising exposure is what you're aiming at. And of course there are always constraints to how large an exposure you can have, so what about those? If the exposure you're calling 'ETTR' at base ISO causes you to get camera shake and insufficient DOF for your subject, is it still the 'correct exposure'? If it isn't, then a smaller exposure would be 'correct' in those circumstances, wouldn't it? And if raising the ISO caused less noise, that would be an improvement rather than 'lying to yourself', is it not?

There are a few things that I think you've said that don't fit the reality. I pointed them out in earlier posts. So things that seem to me to be confused in your mental model are (at least)
- the relationship between exposure and noise.
- the role of maximum recorded exposure in DR.
- the relationship between noise and DR.
- the constraints on exposure.
- the difference between the nature of the input and output of a camera.
and several other things. As we discuss more, I can try to work out how I think these things are connected in the way you are thinking, but I can't see inside your head.

Both mischaracterisations. You're engaging in a very common (and ego based) fallacy which might be called "I'm a pro so I know." There are several problems with it. First, there's quite a few pros that don't know, so saying just that you're a pro doesn't prove anything. Second, it kind of assumes that you speak for all pros, and thus leads you to wrongly decide that anyone who disagrees with you can't be one. So far as Iliah goes, I've come to realise that he doesn't say anything without a great deal of thought. It's also a lot to do with learning style, as I said to Don B upthread somewhere. Different folks approach learning and its application to problem solving in different ways. Some take a trial and error approach, where they try different things, find out what works for them and adopt it. No problem with that. Others take a more model based approach - which is to try to understand how the system they are dealing with works then apply that knowledge to the problem they want to solve. In my experience those that adopt the second approach generally end up with better solutions more quickly, whilst those that take the first will often find good solutions, generally in a more time, depending whether you factor in the tie taken to understand how the system works or not.

OK. I could quibble with some of that, but let's take that as a working definition, at least for now.

Both can be controlled. Shot noise by controlling the number of photons incident on the sensor (which equates to exposure if we ignore sensor size). In the majority of cameras the ISO control offers some control over read noise, but not in a documented or standardised way - you need to investigate you camera to know how it works in this respect.

Yes

I find that to be so simplistic as to be unhelpful. In the best of all possible worlds, the best SNR is the highest one. How much or which type of noise is 'objectionable' is dependent on so many factors - usage - viewing size - characteristic of the noise - artistic intent - whether the consequences of reducing the noise are more objectionable - and on and on.

That's the only way of increasing the shot noise SNR. It has no effect on read noise.

That's not a definition of ETTR that I would subscribe to. As I said earlier, ETTR is a means to an end, not an end in itself. The end goal is to maximise exposure subject to your working and pictorial constraints. ETTR - that is increasing exposure until a displayed histogram shows that all the recorded exposures in the image are within the bounds of the histogram, but there is no free space 'to the right' - is one technique that can be used to achieve that goal, but there are others. One of the issues with ETTR is what the histogram actually represents. So far as I know, no present camera offers a raw histogram. There are hacks to try to get around that of various kinds, some more successful than others.

Nor does it get less light on the sensor - so if the exposure is limited by working and pictorial constraints, boosting ISO is not an issue. And since on most cameras, at least over some of the ISO range, boosting ISO will reduce read noise, it's worthwhile in those cases.

Theres a question worth asking pure ETTR advocates. If you've set the slowest shutter speed that you can whilst avoiding shake, and you've set the widest aperture that you can, which will give sufficient DOF, and the meter shows 'underexposed' at base ISO, what will you do?
1. Take the photo at base ISO with that exposure?
2. Increase exposure and risk shake or insufficient DOF?
3. Increase the ISO?
4. Decide not to take the photo?
and why is your choice the right one?