One of the major points of concern for the digital photographer is color temperature. That might be a difficult term to fully wrap your head around, but it’s essential for anyone shooting in color to understand.

What is this “color temperature” you speak of?

Color temperature is a characteristic of light. Every light source can be measured by its luminosity (or brightness) and by its color temperature. Color temperature is not the same as hue, though it obviously deals with the color of light. In this sense it’s important to associate two colors with the idea of color temperature: blue and red. They are in the opposite direction in terms of the color temperature spectrum. That spectrum is measured in degrees Kelvin (K). However, in a twist of illogical denomination on said spectrum, the lower the number the warmer (redder) the temperature, the higher the number the cooler (bluer) the temperature. The warmer end of the spectrum lives around 1700 degrees Kelvin, which is in the neighborhood of a match flame. The cooler end of the spectrum is upwards of 15,000 degrees Kelvin, which is about the color of a clear, pole-ward sky. That is to say, pretty blue.

How do I use this information in the real world?

When you’re shooting either digitally or on film, you need to consider white balance. Shooting digitally affords you perhaps more control over this as you can set your white balance manually and in very small increments. On film you can choose film stocks which are either daylight balanced or tungsten balanced. Daylight balanced film stock (being on the cooler end of the spectrum) is intended to be shot outside in- you guessed it- daylight. The Result is that a white surface shot in daylight on daylight-balanced film (or daylight calibrated white balance on a digital camera) will, when properly exposed, look white in the resulting photo. If you took that same stock, and shot it indoors with tungsten balanced lights (which most lights tend to be) a white surface, and indeed the entirety of your image will have a blue tint to it. Take that same photo indoors with tungsten-balanced film stock (or a tungsten calibrated white balance on your digital camera) will result in a white surfaces looking white. On the other end of that, a tungsten calibrated white balance shot in daylight will result in a warm, orangey tint.

Now as far as digital photography is concerned, white balance setting doesn’t have to be anywhere near as permanent a decision as it is with film. You can’t change your film stock’s white balance on the fly; you just need to literally change the roll out of your camera. But with a digital camera you can change your white balance at any point. Further, and this was covered to some degree in our article about RAW photography, you can actually change the white balance of a RAW photo file after it’s shot. When you open a RAW file in a photo-editing program (like Photoshop) you can actually adjust your white balance by altering the color temperature of the photo, and you can do so in extremely small increments, as color temperature is measured in a wide spectrum. This is super helpful since in-camera setting jump a lot in degrees Kelvin and the color temperature of, say, the sun can vary a lot depending on the time of day, how cloudy it is and even what your latitude on the planet is. Nuts, I know… This level of flexibility opens a lot of creative doors as well, though.

Also of note is the manner in which other forms of light read when the light balance is set a certain way. For example, tungsten calibrated white balance will turn florescent lights green.

These factors can be particularly interesting when you have variable temperatures from different light sources in one image, like the warmth of firelight on a face in a room fill with cool, ambient moonlight.

Also, setting white balance against the color temperature of the light source, or pushing it a bit further, can help tell a story. Making a family photo a little warmer in color temperature can imply something very different than the greenish, sickly tint you got because you were shooting under a florescent.

When all that is taken into consideration, hopefully you can achieve something closer to what you intended before you started shooting. If anything it will give you an understanding of why your images look a certain way and how to change it if so desired. The beautiful thing about color temperature and white balance is that it’s a great variable to experiment with and discover avenues you didn’t quite before.