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Phtography Talk
White Balance and Color Temperature
by Bob Dean

Most high end point and shoot and virtually all digital SLR’s have provisions for selecting white balance and color temperature. What this means is pretty simple. The photographer can select the camera’s method of representing color on the recorded image.

White balance is simply the camera’s way of looking at all colors of the spectrum and generating true white. The basic setting is AWB or auto white balance. In this mode the camera looks at the entire scene, assumes the light is about midday and comes to a conclusion as to what white should look like. The most creative white balance control is the custom one. Depending on your camera (check the manual) you can find a white object and use it to set the white balance so the camera can accurately record white in the light that’s available. You can also use other neutral colors to cause a shift in white balance but be careful; you can get some “interesting” and perhaps not too pleasant results.

If you really want to be able to alter a scene however, try the color temperature adjustment on your camera. Light is measured in “color temperature” and there is a relation between this value and warmth or coolness of the light. It’s a little confusing, but the lower the color temperature, the warmer the light. This is a collision between science and art. Some examples are:

  • Candle light: 1500 degrees
  • Incandescent light bulbs: about 3000 degrees
  • Morning and evening light: between 3400 and 4000 degrees
  • Midday light: is 5000 to 5500 degrees
  • Flash: typically between 6000 and 6800 degrees
  • Heavy overcast: 6000 to 7500 degrees
As is common practice when discussing color temperatures, all of these numbers are in the Kelvin temperature scale. Check out the final paragraph of this article for more details.

There are two ways to compensate for color temperature. One is the post processing phase (on the computer with an image processing software tool) and the other is in the camera. Anything you can do in the camera is inherently better because you are not disturbing the digital image through recompression and manipulation. It does take some experimenting to use color temperature corrections but consider these tips:

To warm up a scene, adjust the color temperature to a high (cooler) value. This is not as confusing as it first appears. The color temperature adjustment on the camera tells the software what color the light is on the subject. If you tell the camera that the light is very cool (high color temperature) the processor will “warm it up” to come to the midday neutral color. If you’re shooting at midday, try setting the color temp to 6500 if your camera uses degrees or to the “overcast” setting if it uses verbal settings. In both cases the camera will warm up the scene.

Don’t rely on the LCD screen on the camera to give you instant feedback on color. These little screens are great for checking to see if you recorded the image, if the exposure was relatively OK and if your composition was close to what you wanted. They are not good for checking color, focus or details of the image. You don’t see those until you view the image with a calibrated monitor or properly produced print.

Using color temperature creatively requires the old fashioned concept of taking notes and then reviewing the final images. From this you can start to learn how to most effectively use this creative control.

By the way, for those of you interested in how color temperature measurements are determined, here is a brief physics lesson. In you were to take an object physicists call a black body and heat it until it started to glow, the color of the object will be related to how hot it is. The lower temperatures will generate a warm orange glow that will become whiter as the temperature increases. The temperature is measured on a scale known as the Kelvin scale. This is similar to the Celsius (or centigrade) scale in which water freezes at 0 degrees and water boils at 100 degrees, but it is shifted so that 0 degrees Kelvin is the theoretical absolute zero of approximately -273 degrees Celsius.