The 'histogram to right' theory a la Luminous Landscape is technically correct, in that it minimises SNR. Note that article was a bit controversial when it came out, as it was suggesting the opposite of what most people were doing (underexpose half stop so as to not blow highlights, important when shooting JPEG).
I think it's interesting, and theoretically correct, but in practice I just aim to get a nice bell shaped histogram without clipping either highlights or shadows. Remember it's easier to recover shadow detail than highlights, even with RAW (which I always shoot where possible).
The problem with "histogram to the right" is that strong colors that saturate just one of the channels don't appear all the way to the right. It's possible, especially with blue water, to blow highlights without touching the right side. That's the lesson here.
What's important is understanding the histogram display in camera and how it relates to good exposure underwater. That's what Bonnie was looking for.
I would like a readable, simultaneous three channel histogram even if it just showed the upper quarter of the range.
Level of exposure will not effect color in a digital camera as it can in film. If you desire to avoid cyan water in the type of shot in Bonnie's example, you will need to correct it using a filter or PS. Underexposing it will just give you dark cyan. The camera can only record what its lens sees, and in this case it sees cyan water.
I believe that (some) rules of exposure are different for digital and film. With film, the level of exposure effects color saturation and color balance. With digital, it only effects SNR. Exposing strobe vs. ambient works the same way, but with digital there is no advantage to overall underexposure.
That is because silicon sensors are linear and film is not. Craig and I rambled on for awhile about this on another board. This actually is the best evidence for the point I was trying to make.
