White balance and degrees Kelvin

If you have seriously done photography for a while you would know the term "white balance". You may even know that white balance can be measured using the Kelvin temperature scale. Digital cameras have the ability to adjust the image to compensate for the environmental white balance being photographed. This represents a tremendously useful function as an off-colour scene will appear unusual. A common place where this is noticed is with people's skin tones. They may come out blue or green or yellow, anything but what a proper flesh tone should look like.

The Kelvin scale is related to the Celcius scale. A change of 1° is exactly the same in both Celcius and Kelvin. The difference is their starting points; 0 on the Celsius scale is the temperature that water freezes at. For Kelvin, 0 is at absolute zero, the coldest temperature possible. Water freezes at 273°K. So, what does temperature have to do with the colour of light?

Things that are very hot glow. When you file metal down using a grinder, the hot filings glow and emit light. The colour of the light hot metal emits depends on the temperature. At low temperatures, around 2000°K, the light emitted is red in colour. That changes to yellow, then, around 5000°K it becomes "white-hot." As temperatures increase past that various shades of blue light are emitted.

Your digital camera comes with the ability to determine white balance, but only in a very general manner. You can also choose to select specific white balance values, such as tungsten, cloud, shade, sun, and so on. The problem with picking these "ball-parked" values is that white balance is usually off by a bit. Some cameras allow you to fine-tune that setting to obtain better results. The grid shown above right is one such method. You can alter the colour balance by moving the point cursor in the desired direction.

I find the best way to set white balance is by customizing it through the custom white balance function. The manner in which it is set varies, but the outcome is the same. A white sheet of paper works as a neutral example, but any gray or even black object will suffice as long as there is no tint present. Follow the instructions in-camera or from the manual and you will have obtained the perfect white balance for that situation.

In the hockey photo above, I used the ice as a neutral object. Setting my camera to record the custom white balance was easy; a couple of button presses and it was finished. After that, the ice looked white instead of sporting a greenish hue. Using custom white balance or fine-tuning an existing setting will improve the quality of your photos as skin colours will be true instead of some peculiar shade of blue or orange. You'll be amazed by the difference.

Thanks for reading.     Ericspix     Eric Svendsen