The Exposure Triangle Is Misleading And Unnecessary.

Definitely, if you are shooting JPEG, the ISO setting is essential. We agree on this, yes?

If you are shooting RAW, the ISO setting is necessary unless your sensor is ISO invariant. I would say that the definition of an ISO invariant sensor is one in which you can get the exact same result using you RAW editor’s Brightness or “Exposure” slider as you can by you can by adjusting ISO in the camera.

I tried using Canon’s DPPro software to adjust the brightness in my RAW images to equal the effect of the camera’s ISO setting, but it did not work. I took fixed manual exposure shots in daylight, using a tripod and adjusting ISO. The ISO 800+ shots were blown out. Unrecoverable.

You may be correct in theory; I have no idea. But in practice, on the Canon platform, the ISO setting definitely matters for both JPEG and RAW.

This is a situation where ISO doesn’t matter, because presumably you control your lighting for an ISO 100 anyway, as well as the shutter and Aperture you want, correct?

In my view, the photographer still needs to account for the ISO of 100, even though it’s being held constant. It seems like we should just move off the ISO discussion and talk about the paper and the lighting setup, which is much more interesting.

Or they can account for the outcome.

Yes, and nothing like

Some people (not me, fgs!) are doing OOC JPEG output. They like to have a certain lightness on their images, depending on the scene. For them, it is important to understand how ISO, F-stop and shutter speed interact. Call it a triangle or anything, but you need to understand the three things. I prefer a more practical approach.

c) making the lighting brighter

"fill it"? Needs explication.

The noise source is not an "analog amplifier," though, through brightening, the noise is made more visible. Raising ISO (without changing exposure) lowers the noise.

Analog amplification in practice in modern cameras does not add to the input-referred read noise, and may make that smaller.

Hey, can I request a new forum feature? It would be called "Sparing my blushes". It's function would be to search all posts for a certain phrase and issue an automatic correction addendum to each post.

Thanks

Dave

p.s.

I found a very useful article on DPR from back in 2007 all about ETTR and ISO technicalities and strategies. Bizarrely, it seems to support what people are saying here. Most disconcerting 😁

IMO, the best thing that can happen to me on the forum is when I have made a mistake (I am trying to avoid it, though). When others have corrected me, I have learned something, and the time spent on forums is not entirely wasted :).

Mistakes and failures (in business) are opportunities to learn, not a reason to feel humiliated.

I think many folks assume the lighting is a given. But looking for ways to make the scene brighter is very effective, and should be front of mind for all photographers, even beginners.

Have you calculated input referred read noise vs ISO curves? Failing that, have you looked at the curves that others have calculated?

Analog gain reduces the input-referred effects of noise sources further down the pixel pipeline than the programmable gain amplifier.

Bolding mine. WRT the bolded text, that's not true in any camera system for which I've calculated photon transfer curves.