25%WHAT IS A WHITE BALANCE & WHY IS IT IMPORTANT?
White Balance is an important function found in most Digital Cameras and can mean the difference between a beautifully exposed and balanced digital portrait and a picture resembling the Jolly Green Giant.
It all comes down to the concept of colour temperature. The colour temperature is a way of measuring the quality of a light source and is based on the ratio of the amount of blue light to red light. For example lighting with a higher colour temperature such as fluorescent tubes has more blue light than lighting with a lower colour temperature such as standard light bulbs.
The human eye in combination with the brain can see white paper as white paper no matter if viewed under strong sunlight or in a bulb lit room. Digital cameras however use built-in sensors to measure the current colour temperature and then use an algorithm to process the image in an effort to reproduce the colours a human might see.
Most digital cameras are set to use an automatic white balance. The automatic settings usually do an adequate job of adjusting to different sources of light. Unfortunately the algorithm being used may not always be accurate enough to make every situation correct and the settings may need to be changed manually
The most common white balance settings are: daylight (adjustment made for direct sunlight); cloudy (when shooting under cloudy skies); fluorescent (used when fluorescent lamps are the main source of light) and incandescent (standard light bulbs lighting the scene).
It is important to choose the correct white balance settings otherwise there may be a colour shift in the image. For example, suppose the camera is set to use a colour temperature of sunlight to take an image of an object illuminated by indoors. The camera will expect lots of blue light and less red and will therefore mute blue and boost red accordingly. However, in an environment illuminated with incandescent lights, colour temperature is low with more red than blue. As a result the image will come out reddish or yellowish and the colours will be incorrect.
Setting the camera to the correct white balance is very important and time should be taken to make sure that the chosen setting gives an accurate colour representation. Some of the more advanced digital cameras have manual settings for measuring the colour temperature of an environment's lighting and allow you to define your own white balance reference.
Before taking a critical shot, you can focus/zoom at an area in the scene which is white or neutral grey and allow the camera to calibrate it's settings from that. The camera will then use this reference when taking the shot. Auto white balance is fine most of the time but for those occasions when you are not happy with the colour cast of your picture, choose one of the presets. If this still doesn't give acceptable colour rendition, try manually setting the white balance by using a white card or sheet of paper. For ultimate control over white balance, consider shooting in the RAW file format, and adjust the white balance afterwards.