Basic Training
Intro to White Balance

Kyle Cassidy
September 2008

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White is white, right? Well, yes and no. Take a white sheet of paper - it looks white. Look at it under a red light bulb, though, and it looks pink. You may not see red light bulbs every day in the course of your videography, but the light that you do interact with on a day-to-day basis has a very distinct impact on the colors your camera sees. In order for your camera to record colors accurately under different lighting sources, it needs to be white-balanced. Your brain white-balances automatically - you can walk from bright sunlight into a room lit by overhead fluorescent bulbs, and your brain automatically readjusts for the slight shift in coloring. If you're careful and pay attention, you may notice slight differences. Take a look around the room right now at different lighting sources, and see if whites look redder or bluer under different conditions. What colors do the light sources themselves seem to be?

Fluorescent lighting, you may notice, puts a greenish cast on people, while tungsten light makes things look a little red. The people who built your camera know this, and physicists who study light have spent a lot of time trying to figure out exactly why things look the way they do. The color of light, for very complex reasons that you don't really need to know, is measured in degrees Kelvin and is referred to as color temperature. The color temperature of bright sunlight is about 6000K (six thousand degrees, Kelvin). Tungsten bulbs are considerably cooler at between 3000K and 3500K. Most of the other light that you will be working with exists somewhere in between.

By telling your camera what type of light you're working under, you can correct for types of light that don't look like sunlight and make your colors consistent from shot to shot, regardless of the light source. Without the proper balance, your colors will shift a bit and affect everything in your shot (e.g., skin tones, the color of water in a tropical scene, etc.), creating a less realistic look.

Your camera will most likely have a number of presets which are useful starting points. These have nearly universal icons for shade, sunlight, fluorescent and tungsten. There's also an automatic setting where your camera will make its best guess as to what the color balance ought to be. It's often good enough, but rarely exact.

Fluorescent's green shift is not as harsh as it once was, and you can now buy daylight-balanced fluorescent tubes, which means the lights emit nearly the same color as the sun. This is very helpful if you're shooting a scene with both interior light and sunlight - more on this later.

One shade of light isn't actually any better than any other, but, since the sun is the light we know best and the one we've known since long before we had others to compare it to, every light is an imitation of sunlight. For that reason, sunlight is the temperature of light that we try to duplicate. On some other planet that's lit by a giant fluorescent tube millions of miles across, filmmakers may be trying to make their other lights look a bit green.

Here are the color temperatures that correspond to the various white-balance settings you'll find on your camera:

Auto: your camera's best guess
Sunlight: 6000K
Clouds: 6500K
Fluorescent: 5500-4000K
Incandescent: 3000-3500K
Temperature: you manually pick a temperature (in degrees Kelvin) that most closely approximates your light source (very useful with lighting sources that have a range of color temperature)
Pre/manual: you manually set the white balance by showing the camera a specific white or neutral grey surface

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