White Balance: what you need to know

White balance 1

Do you know how to effectively control White Balance on your DSLR camera? Accurately recording color temperature during exposure is a critical skill thall all photographers should learn. (Copyright 2013 / Andrew Boyd)

Your DSLR camera is probably set for Auto White Balance, or AWB, and that’s fine up to a point. The key to Auto White Balance is understanding what’s it’s doing and how it’s doing it; from there, an understanding of white balance and how to control it will definitely make you a better photographer.

WHAT IS WHITE BALANCE?

Kelvin scale

An illustrated Kelvin scale of relative warmth/coolness. The cooler (read bluer) the light source, the higher the Kelvin number, and vice versa. (Copyright 2013 / Andrew Boyd)

 

When making an exposure, your camera must adjust for the color temperature in a given situation. What is color temperature? It’s the relative warmth or coolness of your shooting scene, measured in degrees Kelvin, or Kelvin temperature. (Check the link there for another post that explains Kelvin Temperature).  Put at its simplest, the warmer the light in a scene, the lower the Kelvin temperature, and vice versa: so a room in your home, lit by lamp light, has a Kelvin temperature of probably around 2800 degrees. Outside in the shade away from the sun, the bluish light there will read around 8000 Kelvin. Middle of the day direct sun has a Kelvin temperature of around 5500 to 6000 degrees. (Strobe units are all designed to shoot around 5500 degrees Kelvin.) So what does this mean for your camera?

 

In order to make exposures that the average person will find acceptable, cameras must take the Kelvin temperature in a room and render it into a neutral skin tone exposure: usually something closer to the 5500 degrees Kelvin described above. Cameras do this by searching your composition, right before the exposure is made, for something that is WHITE.  The camera’s computer then takes that information—‘this is a white object’—and creates color for the rest of the scene based upon that white object.  This is ‘Auto White Balance’ at its simplest, and almost all of the time, it works great!

 

But: sometimes it fails miserably. This happens most often when there is no white object in your scene. I’ve seen this a lot lately out of smart phone photos. If the background is, say, green, and your subject in front of that green wall has no white clothing on, the camera doesn’t know how to render the colors in the photo. A weird color cast is usually the result.

White Balance 2

The problem with Auto White Balance: top photo is AWB and with no white reference in the frame, the camera makes a guess at color temperature. Bottom photo taken after a Custom White Balance is set. This color is much, much more accurate. (Copyright 2013 / Andrew Boyd)

So Auto White Balance won’t work here. How to fix it?

SETTING A CUSTOM WHITE BALANCE

You’re going to have to consult your camera documentation for your particular white balance procedure but the basic approach is the same:

  • With your camera set for Custom White Balance (or something similar), you’ll shoot a frame with a large white reference card filling the center of the frame. It’s critical that the white card be under the same illumination that you want the white balance set for.
  • You’ll then go back into your camera settings and tell the camera to save that white balance as your Custom White Balance. (Many cameras will allow you to save several versions and even name them. This is handy if it’s a situation you shoot regularly.)

The goal is an accurate rendition of the color within your frame.  ‘Before and after’ example shots can be truly surprising as our eyes are accustomed to making allowances for different color casts as we move through our day. This just gets past that and gives you great color, meaning less fixing in Photoshop and better overall results.

Auto white balance

Top exposure made with Auto White Balance, and it does a pretty decent job of rendering this scene, until you compare it with the bottom version, made with Custom White Balance. The bottom photo takes the white balance reading off of the white sofa cushion. 1/500th sec @ f2.8, ISO 6400, Canon Macro 50mm f2.5 lens on a Canon EOS-1D X camera. (Copyright 2013 / Andrew Boyd)

Hi, I’m Andrew Boyd, a.k.a. The Discerning Photographer, and I hope this post has been interesting and informative. Please leave me a comment about it, let me know what you’d like to see more of on the site! You can also sign up for email delivery of all future articles or my RSS feed. Or subscribe to our Facebook page ,Google+ page or our Twitter feed. Thanks!–DiscerningPhotog

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