How to Set White Balance
Setting White Balance is simply changing the background color of photographs.
White balance can be really confusing at first. Remember how film would turn out greenish for a picture under fluorescent light, or if the area was just lit by incandescent bulbs how the picture would look yellow? Maybe you can remember taking a picture of somebody in the shade and it didn't look that good even if the photograph was properly exposed.
White Balance makes fluorescent light, tungsten incandescent lights, and daylight all look about the same to the digital camera, just like it looks about the same to your eyes. There is film available to do the same thing, but with digital SLR cameras, we just change the setting instead of changing the film!
White Balance in digital cameras fixes lighting problems. Some digital cameras do it automatically. Knowing which settings are best for the situation can really help.
The settings are based on Kelvin temperatures for the type of light that is given off from an element burning at higher and higher temperatures. Shade has one of the highest temperatures and has a bluish cast to it.
1900 K is for a candle flame
2800 K is for Tungsten or incandescent light bulb (standard light bulb)
3400 K studio or spot lights
4100 K moonlight
5000 K Typical day
6000 K Typical flash unit. Also the same as Shade
6500 K Strong daylight
7300 K Shade
9200 K Analog TV screen
Shade as it turns out is the most useful thing for me to remember. I can also use the Shade White Balance setting to make my high noon daylight pictures warmer, as well as things in the shade. Setting higher Kelvin temperature will give warmer tones to high temperature lighting like shade, and setting lower Kelvin temperatures will make lighting that is too yellow or warm look brighter, like pictures under an incandescent light bulb. For example, setting the Kelvin temperature at 3200 K would produce warm pictures under incandescent light bulbs (regular light bulbs) because 2400-2800 K would make incandescent light bulbs look normal.
Remember how blue light bends more then red light as discussed in the Lens section? Blue light scatters more in our atmosphere, making the sky blue during the day, and making subjects in the shade bluish. Sunsets are red partially because of the atmosphere, but mainly because the sun is shining directly at us though the atmosphere sideways. The blue light is scattered, leaving mostly the red and yellow light visible.