Photography is all about light. Once you master the concept of light you will begin to understand photography. But does light have color? Does it have temperature? Well yes! But first, White Balance (or “WB” thereafter) is the process of removing unrealistic color casts, so that objects which appear true white your photo. That being said, you should know that our eyes are very good at knowing what is white under different light sources, but digital cameras often have difficulty with auto white balance (AWB) — and can create blue, orange, or even green color casts. Understanding digital white balance can help you avoid these color casts, thereby improving your photos under a wider range of lighting conditions specially if you shoot in JPG rather than RAW because RAW format preserve all light temperature options that you can retrieve later on in post-processing.
The unit for measuring light temperature is in Kelvin (K). A light with higher color temperature (i.e., larger Kelvin value) has "more" blue lights than a light with lower color temperature (i.e., smaller Kelvin value). Thus, a cooler light has a higher color temperature. The following table shows the color temperature of some light sources.
Light Sources: Color Temperature in K
Clear Blue Sky : 10,000 to 15,000
Overcast Sky: 6,000 to 8,000
Noon Sun and Clear Sky: 6,500
Sunlight: 5,400 to 6,000
Electronic Flash: 5,400 to 6,000
Household Lighting Bulb : 2,500 to 3,000
Candlelight: 1,200 to 1,500
Note that an electronic flash is intentionally made to have a similar color temperature than sunlight.
Our human brain is a complex system that can quickly adjust
to different color temperatures. Our eyes give the signal to our brain to see a
white paper as a white paper no matter in what condition it is viewed under whether
strong sunlight or in a room illuminated with fluorescent light. Unfortunately,
camera sensors can only record the colors in certain range of color
Your camera comes with preset WB settings and those usually are:
Auto (AWB) –the camera makes a guess on a light metering basis. It works in many situations but sometimes in trickier situations like in weddings and concerts the camera will get confused.
Tungsten – that little bulb symbol on your camera display. Usually used for indoors under tungsten (incandescent) lighting such as bulbs. This settings cools photos by adding blue i.e. the opposite of yellow to match the color cast.
Fluorescent – fluorescent light have that cool blue color case. This setting compensates for the ‘cool’ light and warms up your shots.
Daylight – symbolized by that sun icon, this setting is used for noon sun or sunny average daylights.
Cloudy – symbolized by a cloud icon, this setting warms things up a little more than ‘daylight’.
Flash – this mode will warm up your shots a little.
Shade – symbolized by a little house with a shady area next to it, will also warm things up a little.
On pro DSLRs you can also set manual white balance by entering a Kelvin degree.
Now if you are a precision freak and want to nail that white color 100%, DSLRs also have the ability to get a reading from something white (or grey). Shoot anything white (or grey) like a paper or an object around you then switch that WB mode to “Custom WB” and select the image you just shot.
Setting WB incorrectly may cause a different color cast in the image than the one you remember seeing in that viewfinder when you took the image. See examples below for different WB option I took of the sunset and changed in Lightroom.
Unless you are shooting a product or a brand catalogue, when
it comes to creativity, there is no right or wrong in WB selection. You might
want to intentionally give that sunset above a blue-ish look to give your
audience the look-n-feel of a dramatic landscape. You are the decision maker
but as an advice always shoot in RAW and decide later in post-processing on the
temperature you want.