I receive lot´s of questions on white balancing. Most people are staggered , when I tell them: “Don´t even think of touching that button”. Here is why.
White Balancing was introduced to video cameras (imagine Trailer VO voice) in a world where Da Vinci was considered an Italian painter and Red Giant a tomato brand. At a time when color correction or grading for most ENG or documentary material wasn’t even an option. So it was necessary to get it right in the camera while shooting. This was later brought over to consumer camcorders.
As most convenient things, WB comes with a trade off and that is noise, especially in the blue channel – which is the noisiest anyway.
If you shoot under tungsten the WB (manual or automatic) tries to fight the warm, orange light by raising the gain in the blue channel a few db- and there comes the noise.
Usually camcorders have at least 3 settings. 3200k or Tungsten, 5600 k or daylight and a button for manual WB. 3200k raises the blue gain to compensate for the warmish tones in household bulbs, if you use the manual WB and a white/gray card it is even more aggressive – hence even more blue noise.
This tests where made with a HVX 200 under a 60 watt tungsten bulb. The results are similar in all video cameras, except maybe the ARRI Alexa, which has a surprisingly clean blue channel . Maybe ARRI is lowering the red gain instead of raising the blue, which would make much more sense (but that was only a prototype, so who knows).
The first 4 pictures show the effect of the different WB options.
Here are the blue channels. As you can see, the manual WB and the 3200k settings are the ones which introduce the most noise, especially in the shadows of course.
If you leave the setting to 5600k you get a much cleaner picture, but it has a very warm tone, not what everybody always wants.
And here comes the interesting part. If you lower the red levels in post, instead of raising the blue in camera and then push the exposure a bit, you get a nicer, sharper and cleaner overall picture.
So don´t even think about touching that button (unless you don´t have the time or nerves to do at least a one-light color grading in post).