Hi Bob, It was recently said by a supposedly advanced photographer that if one sets the white balance using the camera's menu, that their RAW pictures would improve. This doesn't make sense...does it???
Doesn't the camera record everything hitting the sensor when shooting RAW files? If true, then the only change would be the image seen using live view.
You are correct, the WB settings have no effect on the RAW data, however, it may help the RAW processing software to provide a better first guess which might save you time and fiddling. I have heard that Aperture makes pretty poor WB choices for some cameras, espeically since they might not be able to read the proprietary WB "setting" in the file.
Histograms are another story. The Histograms are based on the JPEG renderings, so picture choices and WB can affect those.
You are correct and the "advanced" photographer is wrong! White balance does not affect the RAW file in any way. WB is simply a color correction which is applied to the sensor date in order to create a JPEG. It doesn't affect the sensor data at all and the RAW file is simply the sensor data.
A few things do affect the RAW file. One is the ISO setting which sets the gain on the amplifiers of the actual sensor output and another is Highlight Tone Priority (not 100% how that one works!). Both of these are hardware functions (or hardware/software combination) and so they directly affect the data from the sensor and as such affect the RAW data as well as any JPEGs.