Thanks for the link. I sincerely believe that there is no substitute for experience. Before digital was so ubiquitous, the light meter was the best information you could get about the exposure characteristics of a scene and I think we can agree that some of the most timeless and iconic photographs in history were made with a combination of the light meter and experience. I also believe that the histogram is incalculably useful to those who know how to read it, even if it’s an approximation based on compressed data.

When it comes to information, the more the merrier!

It seems to me that the RAW data may have to be massaged somewhat in order for the histogram to make sense to the user (why or how I am not certain of), but it would defeat the purpose of the histogram to display the data after processing by the JPEG system because that system (in Canon cameras, the DIGIC processor) often changes the tone curve as part of its enhancement process, so I’m confident that it isn’t true for Canon cameras at least.

I could do an experiment, taking the same photo in JPEG and in RAW mode and see if the histogram appears different on the screen. Perhaps I will.