White Balance - Impact on exposure estimation

Hi Folks, It's my first post here, after several months of reading and learning from this great forum!

I'm shooting a Nikon D80 with an Ikelite system. Due to the fact that setting a custom wb via whitecard/grey card/sand/my fins is such a hassle with my system (dunno if there's an easy and ergonomic solution from other camera manufacturers), i often shoot in auto wb, and set the wb in post-processing.

As far as i can see there's a catch to this method: the channel histograms that are being shown by the in-camera preview can be far off the mark, and propperly judging my exposures by reading the histograms is next to impossible. Instead, if i manage to set a cusom wb, histograms are very useful for this purpose. I realised this while shooting a wreck in 13m. Using auto wb without flash, histograms were showing a completely blown out green channel, which required underexposing 2stops. I set up a cusom wb using either the sand or my grey cressi gara2000ld fins (both wbs were identical), and voila: no need to underexpose, the green channel suddenly shows up in the histogram!

The other thing that bugs me is the known issue that the in-camera histograms are not raw histograms, but instead histograms of what-would-be jpegs processed by the camera. This is quite annoying.

What about the new D40, D300, D3, 1D? Are they showing real histograms, and are they allowing a quick and EASY custom wb? I dream of a dedicated WB button

Else I'm very happy with the D80, and I hope Nikon will keep on delivering at least one model that has great ergonomy and image quality packed in a small and lightweight body.

I haven't heard of any DSLR that allows the option of displaying RAW histograms. There is a technique for some Nikon cameras that sufficiently emulates it. Basically, what you do is load a RAW image into NX, set it to a special white balance that sets the channel multipliers to (nearly) one, place the resultant image onto a CF card and have the camera set a custom white balance to those values. The image preview will look bad but you can count on the histograms then.

DSLR manufacturers need to offer that option as it would be particularly useful to us and trivial to implement :-)

Interesting, thanks for the info! Can that be done in adobe's raw converter? Are you guys using that custom wb value?

I haven't done it because it doesn't work with the D2xs (although it does with the D2x). My understanding is that NX is required, though. Look for "UniWB" or "NearUniWB" at the dpreview forums. "NearUniWB" is the one you want if you will be using ACR for your conversions.