An Introduction to White Balance


Michigan UP.  Canon 10D 17-40L USM at 17mm.  f11 1sec.

The importance of White Balance:  The rise of digital photography brought several unique new benefits.  Some are easily recognizable, such as the low cost per image and the ability to review shots.  But there's an equally valuable capability that isn't initially apparent to most people as they begin with digital.  White Balance controls are worth a study.  They are so important, they are even available in entry-level consumer digitals.

The effect of White Balance:  White Balance (WB) controls have both technical and artistic merits.  From a technical perspective, accurate white balance is an essential aspect of creating  good photographs.  And artistically, white balance can be used to influence the "mood" of a photograph.  Consider the warm glow of sunset, or the crisp coolness of a cloudy snow-laden day.  Often, these casts can be an important part of the scene.  But these casts can also lend unnecessary distraction to images -- consider the harsh green tint of fluorescent office lights.  Prior to digital, photographers relied upon glass filters to "color correct" for a given scene, or they used specialized film to match the environment.  As with many things, it's better with digital. 
 

Sunrise at 2800K    (f13 at 1/90)

Sunrise at 7900K    (f13 at 1/90)

Light has a temperature.  In order to thoroughly understand the topic, a slight diversion into the realm of physics is necessary.  Different light sources have varying amounts of red, green, and blue light.  This affects the temperature of the light.   This difference in color temperature even has a scientific measure, using the Kelvin scale.  The lower the measure, the redder the light.  The higher the measure, the bluer the light.  Candlelight and sunsets are around 2000K.  Noon on a sunny day is around 5500K.  In the shade, it's about 8500K. 

Trust the camera; most of the time.  Most cameras have an auto-WB feature.  And it generally works well enough for snapshots and most photographic situations.  But there are occasions when the camera won't be able to adjust correctly, and it's up the photographer to take charge.  The most-common of these situations are indoor lighting.  Without proper adjustment, photos under traditional light bulbs will appear more orange than is natural.   Photos under fluorescent lights will appear more blue.  Shady scenes also appear blue.  Most cameras provide "quick sets" for these types of situations, and include instructions in the owner's manual.

Complex situations require simple tools.  For lighting that defies definition, many cameras allow custom WB settings using a "white card."  A white card is just a sheet of typing paper.  The process involves taking a picture of the paper -- filling as much of the scene as possible -- and instructing the camera to use the photo to determine an optimal WB setting.  Cameras differ on how to do this, but the process should be covered in the manual.  Any sheet of paper that is mostly blank and completely white will work.  A few folds in the paper won't hurt, as long as they don't create strong shadows.  There are also third-party products on the market.

Creative photography requires creative thinking. When using WB controls to achieve creative control, there's some thinking involved.  You have to lie to the camera.  If you want to create the effect of a warm sunset, the camera must be set to take pictures as if it were taking an ordinary photo in cool shade (8000K).  This will have to effect of removing blue light from the photo, which allows the red to shine through.  Likewise, photos that feel crisp and cool are made with the camera set for sun set (2800K). 
Consider the following three exposures.  All three are shot with identical settings, except the WB controls have been varied.  The effect speaks for itself.

2800K

Auto -- 5200K

9400K

This technique is effective -- within certain limits.  It won't turn rain clouds into sunny skies.   But it will turn afternoon sunrays into golden light, and sunny expanses into cool meadows.

Try it for yourself.  There are a couple ways to experiment with WB.  Some are easier than others, and the capabilities of your camera will determine which is best for you.  Experimentation is easiest if your camera can save photos in a RAW format.  Simply load your RAW file into the software that came with your camera (or Photoshop CS), and adjust the color temperature setting.  If your camera only supports JPG (or JPEG) files, then you're you'll have to experiment by taking multiple photos, changing your camera's settings each time.

Use RAW files if possible.  The use of RAW files is a topic for a separate article.  Some people swear by them, other photographers prefer the time-savings afforded by JPG files.  Regardless of your preference, it makes sense to shoot in RAW anytime you're uncertain what color temperature is optimal.  This is especially true for sunrise and sunset photos.  Once the camera has assigned the WB setting to a JPG file, there's not much of an opportunity to alter the shot later.  But with RAW files, photographers can wait until they are in front of their monitors before deciding which WB setting is best.


Waterfall photos: Canon 10D on a tripod, using a 17-40L USM lens.
Sunset photos: Canon 10D on a tripod, using a 75-300 IS USM lens.