Originally posted by stevebrot Sadly, the headroom is all in the high values, at least from the purely data perspective
Ya, I really don't think much about a raw data perspective, my viewpoint is all empirical. What can I do with it?
My point to date in terms of raw data, is, using 14 bit raw you never max it out. You always have 100 times more than you can use in a jpeg.
The reason for going to 14 bit raw is to avoid the limitations of 8 bit jpeg, it accomplished what it set out to do, and eliminated the need to worry about colour accuracy and lack of gradation in the low end. 8 bit is fine for what you see. 14 bit is what you need to shift values in post. But I've seen no evidence that you need more than 16 different blacks in your final image. As has been pointed out repeatedly, we regularly pull detail out of completely black values in the original jpeg thumbnails. Maybe you had to worry about such things with film, not so much with digital. There is a lot of detail down there you will never want to access, it's there just in case, and usually the case involves you totally blew the exposure by shifting to the right so much you left part of the image unexposed because you didn't exceed minimum sensitivity. 14 bit raw is serious overkill situation. Even 12 bit is.
If your histogram tells you you're almost all the way to the left, you're good to go, in most circumstances. And I'd argue that's the best approach. But the other perspective is you want the mid section of the course on your subject. Based on what I see, the theoretical stuff is just lame attempts to explain my results. Honestly, I don't know and don't care. It's amazing how often I get drawn into these theoretical discussions with folks disputing my practice and results based on theoretical nit picking. I use theory, only to explain my results. It's not like I and others don't post relevant images.
It's completely inappropriate to try and dispute practical knowledge with theoretical objections. Show me what you mean with practical examples and we can talk. I'm sharing practical observations of how it works, trying to provide some theoretical background. But it's based on my results. Theoretical objections may be of interest for discussion, but they can't change the observed results.
Without practical examples I can't tell if folks are just blowing hot air or are actually on to something. Repeatable samples are critical to extending knowledge. I don't really want to know what you think. I want to know what benefit to me there might be to thinking that way. Then I still want to evaluate if your thinking is straight or you just lucked into something that is actually unrelated to your logic.
My current practice is "Get the back screen jpeg and histogram as close as you can to what you want, clean it up in post processing." There is all the latitude you need with that approach in even a 12 bit Raw.
IN the case of ETTR, I thought about it, I tried is, it doesn't stack up. It will cost you images. Chimping and using the histogram is better, in my experience. The histogram may not be precise, but it's consistent, but you can learn to interpret what you see. I see ETTR as a theory relevant to the days before chimping was possible.
If someone tells me they do it that way... no problem, believe what you want. If they are implying it's what everyone should use, that's a problem.