What is white balance, and why do photographers suggest using a grey card to achieve better colour?

Bobby Partridge, Jarrow

BRIAN SAYS… White balance (WB) is the term used for the process that digital images are colour adjusted to make accurate or natural looking colours.

Cameras need processing to do the same thing, and that processing is auto WB. WB is complicated when there are multiple light sources and colours illuminating the subject, intelligence in the camera is used to identify faces to help the camera achieve good skin tones.

Select a WB preset and you restrict the range of colour illuminating your subject that is compensated for. Daylight changes colour from morning, through midday and on to dusk, so Daylight WB needs to have a range of colour temp it can deal with. Use it indoors with tungsten light and the shot looks too warm toned. Using cloudy or shade white balance in daylight makes warmer toned images that some prefer.

Accurate colour is achieved by measuring the colour of the light illuminating the subject with a colour meter, then selecting Kelvin WB and inputting the measured temperature. One alternative is to use a known neutral object like a grey card.

To make your own white balance for a scene or subject, you shoot the grey card in the same light as your subject, then use the camera menu to define the white balance for that shot. Set the camera to custom white balance and each frame will have consistent white balance. Remember, that if the light changes, you will need to redo the white balance reference shot.

When working with studio lighting, it is good to get a test shot with a grey card (see inset) to set the white balance for consistent images

Use the grey card shot to set the custom white balance and all shots will have consistent colour until you change the lighting