If you want to follow along with me as I explore the world of true raw histograms — defined as histograms in the native color space of the sensor — you’re going to need a a program you probably don’t have. The one I suggest is called Rawdigger. Point your web browser here, and download the version appropriate for your operating system.
There may be other programs that let you look at the real raw histograms. If you know of any, feel free to use it, and please let me know about it.
Load a few raw files into Rawdigger or your chosen alternative, poke around a bit, and compare the histograms to the ones you see in the back of the camera or in Lightroom or Camera Raw. If you want to take a more passive approach, wait for me to post my results, starting tomorrow.