If you look at your camera, you will find a button to change the white balance. You can choose either auto white balance or one of the other predefined settings. But it is also possible to set the color temperature itself. Is there a difference between color temperature and white balance?
I think most photographers will use the auto white balance setting on their camera. Others might use a predefined setting like sunny, cloudy, shade, or tungsten. These settings can give the image a natural look under the right circumstances.
Color and Its Temperature
Color has a temperature. Or better said, temperature has a color. When we look at the definition, it says: "the color temperature of a light source is the temperature of an ideal black body radiator that radiates light of a color that’s comparable to that of the light source." (source: Wikipedia) The temperature is given in Kelvin.
This black body radiator seems like a strange thing, but it’s quite simple. It’s an object that absorbs radiation and thus becomes warmer. Eventually, it starts glowing, just like iron starts glowing when it’s heated. First, it glows red, and when it gets warmer, the color eventually turns white.
Below 1,000 K, we won’t see any color emerging from the black body radiator. But at 1,000 K, it will start to glow a red color. At 2,000 K, the color is orange, and at 5,000 K, it will be yellow. If it is going towards 7,000 K, the black body radiator will be white and eventually blue when it reaches 8,000 K or more.
It won’t surprise you when I refer to the sun. It’s a glowing ball of gas that is very similar to a black body radiator. It has a surface temperature of approximately 5,600 K, which equals yellow light. We don’t see that yellow color because our eyes are neutralizing the yellow color cast. We want to do the same with our camera; we want any color cast removed.
Setting the Color Temperature
Most of us know about the different possible light colors during the daytime. Daylight is yellowish, but because our eyes are calibrated for that color, it appears to be neutral. Tungsten shifts towards orange, and something in the shadows will appear blue. Each of these colors have a different color temperature. Orange tungsten is about 2,500 – 3,000 K, daylight is about 5,000 – 5,500 K, and a shadow in full sunlight is 7,000 K.
These color temperatures can be set on our camera, either with the predefined settings through a custom color temperature settings. The predefined settings are indicated with the symbols sun, shade, cloud, tungsten, K. The letter K stands for Kelvin and allows us to tune in the exact color temperature. Just set the appropriate setting for the right situation, and any color cast is neutralized.
Setting the White Balance
In fact, the last sentence of the previous chapter is telling us exactly the relation between color temperature and white balance. By setting the camera at the right color temperature, we will reach a good white balance. In that case, a white piece of paper will appear to be exactly white in the picture.
I want to show this by a couple of examples, shot with the model light of a Profoto B10 flash at different temperatures and different in-camera color temperature settings. It's a variation of the first example with the different white balance settings during a daytime situation. I made photos of the black and white surface of the Spyder Lenscal card to show the differences.
These examples show clearly how white becomes white when the color temperature setting matches the color temperature of the light. At the moment the match is made, the white balance is set.
Using a White Balance Calibration Card
It can be difficult to determine the correct white balance when different colors of light are present. For instance, the combination of tungsten and daylight makes it difficult to achieve the correct white balance.
Fortunately, every camera has an auto white balance setting. It will determine the color temperature in the frame and set the correct white balance accordingly. The downside to auto white balance is the risk of filtering out a wanted color cast. The red colors during sunset or sunrise are a good example, as these can be neutralized by the auto white balance. The before-after example below shows a yellow photo with an in-camera setting of 5,000 K, the other one has the auto white balance setting.
A lot of modern cameras have different auto white balance options available. These can take a natural color cast into account, leaving those nice, rich colors during sunset or sunrise untouched. These special auto white balance settings might even leave some warm tungsten colors in the frame, instead of turning those warm indoor lights cold and unfriendly.
If a correct white balance is essential, it’s advisable to use a white balance calibration card. Most often, an 18% gray card is used, but this is not correct. The 18% gray card is intended for exposure measurements. You have to use a piece of white paper for calibrating the white balance in the proper way. You could also use a Spyder Color Checker. This card will allow you to make a camera profile to get the color and white balance perfect for the lights you are using.
It is possible to achieve a custom white balance in-camera, not only by measuring a scenery and setting white balance accordingly, but also by fine-tuning the color balance. Perhaps not every camera will offer this possibility, but Canon offers it.
For the photographer that shoots in raw file format, the color temperature for a good white balance can be set in the post. But the in-camera color temperature settings can offer the JPEG photographer a lot of possibilities for fine-tuning the colors.
Is the Perfect White Balance Necessary?
You might wonder if it’s necessary to have the most perfect white balance possible. If you’re photographing subjects for which the perfect color rendition is essential, it will be necessary to have full control over the color temperature and white balance. Using a white balance calibration card or color checker will be imperative.
But in all other situations, an exact white balance is almost never necessary. It doesn’t matter if you are off by a few hundred Kelvin. The reason is simple: the light throughout the day is changing constantly, and colors will differ if the day progresses. It’s often okay to see the changes in your photos. It keeps the atmosphere of the moment.
If you would prefer the perfect white balance in any given moment, it might be wise to use a white balance calibration card for every photo you take. But the downside of this would be the loss of all the nice colors that may be present.
To answer the question about the difference between white balance and color temperature: the color temperature is about the color of light, given in Kelvin. If a color temperature setting is used that will render a white subject truly white, regardless of the color temperature that is present, you have a correct white balance.
How do you use white balance? Do you set a color temperature yourself, or do you let the camera have control? It all depends on the subject you shoot, of course. Please share your way of using white balance and color temperature in the comments below.