What the hell is… WHITE BALANCE?
If the colours in your photos look strange, it’s probably due to colour temperature. Marcus Hawkins shows you how to fix it
What does ‘white balance’ actually mean?
‘White balancing’ enables you to remove colour casts from pictures. Unlike a camera, our eyes compensate for the colour temperatures of different sources of light. For instance, we know that a white sheet of paper is white whether it’s viewed in cool shade on a summer’s day or lit by the warm glow of a lamp indoors. A camera doesn’t. It makes a best-guess at the colour temperature, based on the light reflected through the lens.
Colour temperature?
Light can be measured on a colour temperature scale, using degrees Kelvin. Confusingly, even though we refer to red, orange and yellow light sources as ‘warm’ and blue light as ‘cool’, it’s the reverse on the colour temperature scale. Orange light has a low colour temperature, while blue light has a high colour temperature. This is because the temperature of the light is based on the colours radiated when a black object such as a piece of iron is heated: it will turn from red to white and eventually blue.
Where do I find the white balance controls on my camera?
Some cameras have a WB button: press this and rotate the main dial to scroll through the options on the top display. Or you may find the White Balance menu on the rear control screen or in the shooting menu.
The White Balance menu consists of an automatic setting, plus a number of manual presets that match various light sources, such as Daylight, Shade and Tungsten/ Incandescent. These are indicated by icons and the colour temperature of the light source for which they’re calibrated. You’ll also find a Custom white balance option, enabling you to
manually take a white balance reading from a white or neutral-grey object.
Is the automatic setting any use?
Yes, auto white balance delivers accurate colours in a wide range of situations, but it can get things wrong. It can struggle to give neutral colours under artificial lighting, and it may over-compensate when there’s a predominant amount of blue or red.
You can dial in white balance compensation to improve the colours, increasing or decreasing the amount of blue or amber, or correcting any magenta or green tint. White balance can be automatically bracketed, with multiple versions of an image saved at different settings. But these options are only relevant if you save images as JPEGs – shoot in raw and you can change the white balance later.
How do I do that?
Unlike JPEGs, raw files are the pure, unprocessed image data, with none of the camera’s image-processing options permanently applied. Using raw conversion software such as Lightroom or Photoshop’s Adobe Camera Raw plug-in, you can change the colour temperature and save a version without affecting the original.
So should I just use the AWB setting and fix any problems in Photoshop?
You could, but getting it right in-camera makes processing easier. With auto white balance, all it takes is a subtle shift in camera position or composition, and the white balance can change. This could be problematic when it comes to batch-processing a sequence of shots, as you wouldn’t be able to apply a single adjustment across all the pictures. If you use one of the manual presets or create a custom white balance, then the colour temperature will remain consistent.
How will I know that the white balance setting is correct?
You can use the Live View screen to preview the effect, enabling you to fine-tune the white balance before you take a shot. It’s easy to get too clinical about colour temperature though. If the character of the light is something that drew you to take a photo, the last thing you want to do is to remove it. Try and treat white balance as just another tool for creative photography.