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.