Understanding White Balance
For many of us who’ve recently switched to digital photography there are new things to learn. One of the more confusing new tidbits of knowledge is just how White Balance works.
When we used film we would select a daylight balanced film type for general photography outdoors or with flash, or a tungsten balanced type for indoor lighting. If the lighting was too cool, we might add a warming filter. Under fluorescent light we’d install a filter that adds blue. So, with film photography we were carrying various filters and film types to adjust to the light’s “Kelvin” color.
With digital photography we are still faced with various lighting types (Kelvin color “temperatures”). However, we can now adjust for any light range without filters by setting the White Balance controls in-camera.
How does White Balance Works?
If we recall our science classes in school, we were taught about the Kelvin temperature range in relation to astronomical objects like stars. Remember that a red giant star is “cool,” while a blue/white star is “hot.” Well, reverse that understanding and you have the White Balance Kelvin system used in most digital cameras today.
With camera white balance we use the Kelvin temperature range in reverse. Why? I haven’t been able to determine that yet; if you know, tell me. However, when you walk out on a cold snowy day and your lips turn blue, do you feel hot like a blue star? No! And when you are out in the setting sun in photography’s magic hour of golden light, does the redness of the light make you feel cool, like a giant red star? No, again!
Just remember we use the Kelvin temperature range in reverse, and that warm colors are reddish while blue colors are cool. This is backwards from what we were taught in school. But, it fits our situation better. Blue seems cool while red seems warm to photographers! Just don’t let your astronomer friends convince you otherwise.
Normally, the White Balance (WB) controls are used to adjust the camera so that whites are truly white, and other colors are accurate under whatever light source you’re shooting. Or you could use the White Balance controls to deliberately introduce color casts into your image for interesting special effects.
Understanding White Balance in a simplified way is simply realizing that light has a range of colors that go from cool to warm. This is called the Kelvin Color Temperature range.
We can adjust our cameras to use the available light in an accurate neutral “balanced” way that matches the actual light source, or allow a color cast to enter the image by unbalancing the settings. We will discuss this from the standpoint of the Nikon D200’s camera controls and how they deal with White Balance.
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