Most people are uncomfortable with the white balance settings and just leave it on automatic. This is fine most of the time, but there are occasions when another setting will result in a much better image capture.
If there are only one or two dominant colours in the image, if there is no white at all or if there is more than one light source in the shot, take it off automatic. Believe me, it is much easier to resolve that issue with the white balance settings in the camera before taking the shot than it is to wrestle with masking areas for colour balance in an image editing program.
If you are shooting in RAW, you can set your white balance on the camera or you can do it later in editing. You will get the colours exactly as they are in the light conditions that are present when you shoot.
What is white balance?
You can find excellent tutorials about colour, like this PDF from X-Rrite, if you want to learn in depth. Here we are going to focus on the practical aspects, rather than delve into all the whys and wherefores. Basically, the colours in your photograph will be correct if white is correct. It’s just that simple.
Have you ever noticed that certain light gives things a colour cast? Department stores were notorious for having terrible lighting that turned healthy complexions into sickly green and we can thank the old fluorescent tubes for that colour shift. Now we have fluorescent that ranges from warm to very cool. Incandescent light is very warm, so while that can be more flattering than green, the colours are too red. Bright daylight is very blue and can be quite cold and harsh. You see? Even if the eye is not aware of these differences, the camera records it faithfully and that can ruin your photo.
When we set a white balance, we are really choosing a filter that will render white faithfully under different colour temperatures.
What is white in RGB values? It is what happens when you combine red, green and blue all at a value of 255. While I did say we weren’t going to get into this, it is important to understand the basic concept of light and temperature. A temperature system was devised that measures degrees on a Kelvin scale and this is what is used to measure light. Reds have lower temperatures than blues. Incandescent bulbs light our rooms at about 2700K while daylight at noon on a clear day can reach 6000K. Lighting in a television studio or photo studio is about 3500K. Heavily overcast days can be around 10,000K.
As we mentioned in the beginning, when you have very different light sources converging on the subject you are shooting, guessing won’t work. You need to set a custom white balance for good results. The easiest way to set a custom white balance is to use a white card. Hold it up in front of your subject so it fills the centre of your viewfinder and focus. If focusing is difficult, switch to manual focus. Take the shot. The white balance is set and now you are ready to shoot. It’s that simple.
If the white is correct, that means the balance of red, green and blue will be captured perfectly under the current light conditions. Isn’t that easy?