How to get the best raw exposure, part 2

This may help you understand what white balance is:
www.fastrawviewer.com/white-balance-as-per-channel-exposure-correction

I think that when you distill Jim’s work into practice, it is only applicable for high precision applications. I don’t think it can be used in most sports, street, or wildlife photography. I didn’t know that ETTR is only useful at base ISO. There are many conditions where such shooting is not possible.

But if you’re doing studio or landscape photography, it delivers the best results. In fact, I could see a studio photographer taking this a step farther, by shooting test images and opening them up in a RAW histogram viewer on a PC, and adjusting exposure as needed.

I've done that.

Knowing that ETTR isn't useful at higher ISOs has huge implications for sports, street, and wildlife photography.

"ETTR with ISO", as some (mis-)call it, is of very limited value.

I've said it before but continuing "ISO" with digital cameras has caused more confusion than it's worth.

And now I'll claim that ETTR is a gross over-simplification of proper exposure.

For me, both are equally useless. Come back film ... all is forgiven, ho ho ...

I'm still struggling with your discussion of the Hasselblad shot. You said there was no clipping in the original shot and you supported that proposition by posting the raw histogram for that version followed by a raw histogram for a +1/3 Ev version of the scene. Although the original version doesn't have as much clipping in the green channels as the +1/3 version (of course), the raw histogram DOES clearly indicate that there are max'd out green pixels. Thus, the in-camera histogram indication for the green channel really isn't misleading in any meaningful way, as far as I'm concerned. The inclusion of the post-conversion histograms from Lightroom and Phocus doesn't really add any clarification to the question of how much (if at all) the in-camera histogram is off. Slight differences in default raw converter behavior (including the amount of any highlight shouldering and reconstruction in Adobe's converter) are to be expected and tell us nothing helpful about the in-camera histogram particulars in play with your Hasselblad.

Moreover, the observation that the in-camera histogram continued to show green channel clipping until -1 2/3 Ev relative to the so-called ETTR version is just confirmation of the (near) specular nature of the very small number of clipped green pixels that are present in the white flowers. These (near) specular highlights are commonly encountered in shots that feature sunlit flowers. The missed lesson here that could have been explained to your readers is how troublesome such highlights can be when relying on in-camera histograms and blinkies for optimizing exposure. Specular highlights are the primary reason, of course, for qualifying your advice at the end of the article to "Check the histogram or the zebras to make sure you’re not going to clip any important highlights." The key word in your end-of-article advice is "important," and it's one that isn't really addressed at all. In my experience, the challenge of distinguishing "important" from non-important highlights when reading histograms/blinkies is usually a bigger challenge to effective exposure optimization than the other issues (the impact of application of WB co-efficients and tone curves) that are emphasized.

A successful ETTR photographer needs to be able to recognize why the green channel "clipping" shown in the in-camera histogram of your example isn't important either in the sense that clipping certain highlights are often acceptable relative to the lower tonal SNR benefits to be gained but ALSO in the sense that these green channel-only clipped highlights pose no problem for recovery in a competent raw converter. Without integrating a raw conversion and post-conversion strategy into one's thinking about the optimal exposure determination in the field (ala Adams' previsualization and zone system thinking), ETTRing quickly becomes counterproductive and discouraging (as we've now seen in this very thread).

When I was shooting film, especially slide film, I used the Weston meter with the Invercone and got good exposures. You could do the same on digital with fully manual settings.

However, I usually set digital cameras to evaluative metering, which I find works well.

Don

I call it "pseudo-ETTR" and especially in the age of AI-based denoising, it's really of very limited value.

No it doesn't have huge implications for those genres whatsoever. Folks in those genres can:

1. Know the theory and ignore it as they need to setup for nailing the shot.
   or
2. 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:

www.photonstophotos.net/Charts/PDR.htm

Why does DR fall as ISO climbs?

It's practice when one really knows it.

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.

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?

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.