I call it "pseudo-ETTR" and especially in the age of AI-based denoising, it's really of very limited value.
May 9, 2023
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'P' for 'Professional'
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No you're not. You're disparaging everyone else's knowledge if it doesn't accord with the outcome of your 15 years of trial and error. 'Trial and error' is accurate. Maybe you don't know what that means either.
It's confusing you, which is different. The reason for the confusion is a common one - brain being clogged with prior mislearning.
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No it doesn't have huge implications for those genres whatsoever. Folks in those genres can:
- Know the theory and ignore it as they need to setup for nailing the shot.
or - Not know the theory and don't care anyway, as they need to setup for nailing the shot.
Both 1 and 2 lead to the same end result.
That said, you've further piqued my interest now.
If ETTR isn't useful at higher ISO's what is the point of Bill Claff's PhotonstoPhotos DR charts?
I've always been under the impression that things like his DR charts allow you to determine how much your DR falls away as ISO climbs.
But you're saying that's all irrelevant for ETTR at higher ISO's?
I was under the impression that one could use these charts to gain an understanding of how ETTR to lower ISO might eek some more DR to play with.
Maybe I'm wrong (rendering such charts pointless).
I'm happy to learn something new, but it won't change how folks such as us work, as we HAVE to work the way we do.
Here's the chart for my camera:
Credit Bill Claff:
- Know the theory and ignore it as they need to setup for nailing the shot.
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Why does DR fall as ISO climbs?
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It's practice when one really knows it.
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Never nice parading your ignorance but I'll have a go...
Boosting ISO is similar to underexposing except image lightness is brightened either by increasing analogue gain or multiplying raw values mathematically. This also pushes up the values of the highlights. Because you have effectively underexposed, noise increases. Boosting the highlights may risk clipping.
So, DR is reduced by increased noise and potentially reduced by clipping.
Something like that, probably used the wrong terms.
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And you seem to have tripped up trying hard not to get the terminology incorrect. Which is back to front - understanding the terminology should help understanding the issue at hand. It helps cognition. Trying to fit good terminology to misconceptions generally means things und up jumbled.
'Image lightness' would be 'lightened', or simply increased. 'Brightness' would be 'brightened' or increased. 'Brightness' occurs at the input and 'lightness' at the output, and are completely different things. 'Brightness' is a less fancy way of saying 'illuminance'. 'Lightness' is a recipe for how light or dark a human should see something, and hasn't a direct relationship. You can't transform 'brightness' (or even exposure) into lightness just by multiplication or gain.
This is another common fallacy, that 'underexposure' causes noise. The relationship between exposure and SNR is direct. It doesn't depend on whether exposure is 'under' some reference point or not.
Rather, I think you were trying to apply the right terms to the wrong ideas. Things are really difficult for photographers these days because there are so many sources of wrong ideas, and once you get them in your mind they clog thinking up.
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Because Bill Claff has an entire website full of charts for hundreds of cameras that all show the same behaviour.
If he is wrong and you are right I'm happy to be enlightened?
To be very specific, his chart for my specific camera tells me I have 10.9 stops of DR at base ISO100.
But that falls to 6.9 stops of DR at ISO 6400 and further still to 5.4 stops of DR at ISO12800.
Maybe I've been wrong all these years and these charts are useless?
Shooting low light events and living at ISO6400 to 12800 habitually I was under the impression that auto ISO with 1 stop ETTR exposure would buy me an extra 1.5 stops of DR to play with in post, by reducing my ISO from 12800 to 6400. Given that my aperture and shutter speed are already chosen and are non-negotiable to get the shots I need.
But, of course, if these charts are wrong and should actually be a flat horizontal line from base ISO to infinity I'm happy to learn something new?
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I think what you mean is "lowering the exposure".
If exposure is lowered, SNR becomes worse.
However "ETTR with ISO" doesn't always mean one is going to lower the exposure and "compensate" by raising ISO setting. They may want to keep the exposure and still raise the ISO setting until the histogram touches the right wall; in which case the may gain nothing in terms of SNR but pick a lot of avoidable clipping. -
Dave, I'm thinking it's a joke or it's a trap. Hard to believe that Iliah would ask that question unless he's trying to dredge something out of @BurnImage ...
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I think you are confusing ignorance with accepting the theory but steering it away from laboratory best in class results to actual real world use in the field for fast paced event photography and the like.
One has to balance real world usage against this nth degree of theory and come up with best practice in the field, which will vary by genre.
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No, that's not the reason why DR falls as ISO climbs.
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I don't see anything here that disagrees with what I wrote. It just a question of what the right words are.
So raising the ISO is effectively underexposure. Underexposure reduces SNR. This causes noise. DR is a measure from clipping to a given noise floor. If you increase noise you reduce DR.
Lightness/brightness are just words no one can agree to use in a standard way. When talking about the brightness range of the thing you are photographing I always called it Subject Brightness Range, but then no one else understood what that was!
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Neither :)
It's a question to see how one understands things. -
Iilah is always spot on with the theory, but never ever relates it back to real world dynamic fast moving photography. I know what the game is (I think we all do) and I'm ask probing questions to eke out best practice for the likes of events, weddings, street, sports etc.
Not everybody takes pictures on a tripod in a laboratory.......
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No, it can be any exposure. Sometimes I raise both ISO and exposure.
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Indeed. But I wanted to check my understanding :-)
