I have a friend who took some macro photos of snowflakes with the WB preset to "Cloudy", but lighted from an 11-watt flourescent bulb. Snowflakes look more pleasing with a blue tint, rather than "warm", so to correct for it, the WB slider had to be slid all the way to the left to make it look good. The question I have is, would such a drastic change in WB in any way contribute to the "noisiness" of the photo? I would have been inclined to say no, but I found an article at Red.com which seems to indicate otherwise. To quote:
Ultimately, any white balance change amplifies some colors compared to others. Extreme deviations from daylight can therefore affect image noise in a similar way to higher ISO speeds. This is particularly true with neutrally balanced candle or tungsten lighting, since white balancing amplifies cooler colors compared to warmer ones. This disadvantage can be offset by using a warming or cooling filter directly in front of the lens, or gels with studio lighting. However, these often also end up reducing available light—and progressively more so depending on the strength of the gel or filter.
What got me to thinking about it, was the "known" fact that WB changes to a RAW file are completely non-destructive. So if changing the WB does indeed affect noise, then shooting a scene with "extreme deviations from daylight" will likely affect the the noise/grain in the photo; whether the camera sets the WB, or I change it manually in Adobe Lightroom or similar software.
Does this sound reasonable? Or is there something simple that I'm missing?
Here's a related question, but it doesn't really answer either. Does the camera white balance setting affect the raw image at all?