White Balance

The term “white balance” originates from the world of video imaging where a device (waveform monitor) was used to match the signals from the camera’s red, green, and blue channels to make accurate whites under different colors of light. As you will see below various light sources have various colors or temperatures of light.

For our purposes we will use “white balance” for digital cameras to mean the process of measuring your light source’s color temperature accurately and then using that information to render good color in your images.

What is color temperature and how is it measured?

Color temperature(*) is effectively the warmth or temperature that is emitted from a light source. For example, a 200 W bulb has more intensity in the orange/red end, and shows purples and blues with very little intensity. The term for this is warmth. Daylight has equivalent intensity across the whole spectrum, so you see purples and blues with the same intensity as oranges and reds. But shade or a heavily overcast sky has more intensity in the blue/purple end, so your oranges and reds will have very little intensity. The term for this is "cool".

Here are some examples of color temperatures from common light sources:

Light sources, such as fluorescent and other artificial lighting, require further white balance adjustments since they can make your photos appear either green or magenta.

How does a digital camera auto-detect white balance?

The way that a digital camera works is that the camera searches for a reference point in your scene that represents white. This will/should be the whitest spot. It will then calculate all the other colors based on this white point and the known color spectrum. Simply put: The white balance is the automatic adjustment that makes sure the white color we observe will also appear white in the image.

Setting your camera’s white balance to AWB will provide close color accuracy in many conditions. Your camera will adjust the white balance between 4000K – 7000K using a best guess algorithm. Auto white balance is a good choice for situations where the scene changes frequently. However, there are times when the auto white balance setting swill not be as good:

• Your scene is heavily dominated by one color
• Color accuracy is absolutely imperative
• You are photographing particularly warm or cool scenes (e.g. a sunset)

White Balance Presets

Most digital cameras come with multiple white balance preset options. These presets work well when:

• The light source matches one of the preset white balance options
• Your scene is heavily dominated by one color

Most Common Presets

Tungsten - "Tungsten" is the name of the metal out of which the bulb's filament is made. The color temperature of this setting is fixed at approximately 3,000K.

* Best Use: indoors. However, remember that the window light will be blue by comparison. Otherwise, your exposure will turn out too blue.
* Fun Use: Try setting your exposure compensation to -1 or -2 and try this setting to simulate night.

Fluorescent - This color temperature of this setting is approximately 4,200K. However, these types lights are a different animal. There are many types of bulbs and over time they age and change. The best answer here might be shoot and look. Also, as a side note I am playing with these popular screw in bulbs. The set I currently am using is 2,700 kelvin.

* Best Use: Because of the wide variations of these bulbs I consider it to be a trial and error.

Daylight - This color temperature of this setting is 5,200K.

* Best use: strobe lights - such as studio lights on on camera flash unit.

Cloudy - This color temperature is fixed at 6,000K.

* Best use: direct sunlight and overcast light. This setting will warm your photo by giving it an orange tint. Many photographers use this setting for their landscape and portraits setting.

* Creative Use: sunsets.

Shade - The color temperature of this setting ranges from 7,000K - 8,000K.

* Best use: shooting in shade, when there is no direct sunlight, backlit subjects who are actually in the shade. Without this setting your exposure will turn out with an orange cast. too orange.

* Creative Use: try it in direct sunlight to warm up your photos.

Flash - The color temperature for this setting is 5,400K. This is almost identical to Cloudy but sometimes redder depending on the individual camera.

* Best use: overcast skies. Otherwise, your exposure will turn out too red.

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Using Custom White Balance

The custom white balance option in your camera allows you to take one photo to establish the "white balance" and then apply that to other photos. Here is an example:

 

 

 

 

 

 

 

These images was shot with those little screw in fluorescent light bulbs. The package states that they are approx. 2,700 kelvin. As you can see, the images are very yellow.

My next step was to photograph a white piece of paper. Under standard flash white balance setting it looked like this yellow box:

 

While each camera will vary on how it handles this the next step is usually to go into the menu and tell the camera that the previous image is white. Once that step is done your images will look like this:

 

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