Last week, we made clear the fact that the color of light can be perceived differently depending on whether it is natural or artificial light, the type of artificial light, and even the atmospheric conditions under which we are perceiving natural light. The color of the light (further referred to herein as color temperature) is measured in the scientific scale of degrees Kelvin. Colors that make up the light spectrum have a temperature associated with them. The lower the Kelvin temperature (1500K-4800K), the redder the light (candle light, tungsten bulbs) and the higher the Kelvin temperature (5000K-10,000K) the bluer the light (sunny day, overcast day, even higher a clear deep blue sky).
If we think back to days when shooting film, you might have noticed that most film had the word ‘Daylight’ stamped on it. This meant that your film was color balanced for shooting outdoors in the sun which had a Kelvin range of roughly 5000-5500K, which is in the middle of the color spectrum. When moving into different lighting environments (fluorescent lights, overcast day, tungsten lamps) it was necessary to use a color correction filter in front of your lens to compensate for the change in color temperature. The appropriate filters for the examples mentioned above would be a magenta filter to correct for the green color of fluorescent lights, an orange filter to correct for the blueness of an overcast day, and a blue filter to correct for the orange of tungsten bulbs. The necessary filter is always the opposite of the color you are shooting in, as they will cancel each other out.
Here’s the good news: remembering to use a color correction filter when changing your photographic lighting environment is no longer necessary. Digital cameras have the wonderful ability to a) attempt to auto-detect the the color of the light you are shooting in, and b) allow the user to input into the camera the lighting situation at hand. What it comes down to when setting color temperature is that we want to make sure the color white (or any neutral colors) are interpreted as such, without any odd color casts or hue. This is known as White Balance. This is the single most important step to ensure you achieve color accuracy with your photographs. See below example photos of how the same subject would look under different white balance settings enabled in the camera.
In the above examples, the camera’s Auto White Balance system did not succeed in rendering the whites in the image white, or cancel out the orange/pink color cast of the lights. Of the camera’s built-in presets, the Tungsten setting produced the best results as the lights inside this boutique window in Rome are probably right around 3500K. However, the custom white is far more accurate in rendering neutral color tones and most importantly the white and gray floor tiles.
This is an extreme example of course, but hopefully it will alert you to the necessity of properly setting white balance as per your shooting situation, as we can see Auto White Balance is not always optimal. Join me next Wednesday for Part III of this series in Light & Color Theory where I will discuss how to properly set a custom white balance both in camera and in post-production, why it is absolutely critical to do in-camera if you are shooting JPG files, and how to creatively use color temperature in your photography. An understanding of white balance and color temperature is something that must be gradually formed., which is why this article is broken into three parts. Next week, we will tie all of the pieces together.