Originally posted by spillway Is a white card an indespensible part of a camera bag?
I'm one of those folks who's using ExpoDisc. It basically replaces the neutral color card and, in my opinion and that of many others who've tried it, it's superior to the use of a neutral card. ExpoDisc attaches to the end of the lens like a filter. You use the process for setting custom white balance, but when you're instructed to take a picture, you take a picture with the ExpoDisc on, instead of photographing a white/gray card. Save your white balance, take the ExpoDisc off the camera and shoot. I have not made extensive use of it yet, but in my few tests so far, the results have been pretty good. It seems to me that it's advantageous to get the white balance right when you're shooting if you can, even if you are shooting Raw.
The only problem with ExpoDisc is that it's expensive. The ExpoCap (which seems to be an earlier version of the product) cost me about $55 for my 52mm lenses. I just ordered a larger ExpoDisc and it was over $100. Might be worth seeing how well you do with a blank white card for a while.
Will