The basics of color temperature must always be considered when working with cameras or lights.
Light contains the full spectrum of color, and while the human eye can adjust to make most artificial light appear as a white light, cameras cannot. With this in mind, you must make sure you match the color temperature of your light sources to each other as well as balancing your camera to the correct color temperature.
What is Color Temperature?
Color temperature is often used when describing the color characteristics of light. The color of light is determined by the intensity of the various wavelengths. The measurement of light is referred to as degrees Kelvin, which is a numerical value to the color emitted by a light source.
The Kevin scale is used to define the color temperature of the light source. The scale is based on the light that is generated when a substance is heated. The lower the color temperature, the more red to yellow the light will be. The higher the color temperature, the more blue the light will be.
Tungsten – The color Temperature of tungsten light is around 3200K.
Tungsten lights are basically larger versions of the standard household light bulb. It uses a wire filament made of tungsten. Tungsten has a high electrical resistance, which causes it to glow when an electrical current flows through it. The color emitted by tungsten light appears yellowish. Tungsten light has a nice warm quality to it. It is typically used to light indoor locations.
Most cameras will have a preset white balance to match tungsten light. The setting will add more blue to the camera image balancing out the neutral tones and make the lights appear more white.
Daylight – The color temperature of a daylight light is around 4800 – 6500 K.
HMI Lights (Hydrargyrum Medium-arc Iodide) – HMIs require an electrical ballast to limit current and supply the proper voltage to light. Light is generated by creating an arc between two electrodes within the bulb that excites the pressurized mercury vapor and metal halides. The color emitted from HMIs are blue-ish and are closer to the color temperature of daylight. HMI’s have about four times the light output as a comparable tungsten unit. HMI’s are used to simulate sunlight.
Most cameras will have a preset white balance of 5600K to match daylight.
Fluorescent Light – The typical office or household fluorescent tube will emit a greenish color of light around 4500°K. Fluorescent tubes also come in a variety of color temperatures, including daylight balanced and tungsten balanced.
White Balance – Most digital cameras have a white balance setting. The white balance setting will take into account the “color temperature” of the light sources. If the white balance is not set correctly the image will create a blue, orange, or even green color casts. Understanding color temperature and how your camera’s white balance settings work can help you avoid these mistakes, improving your images under a variety of lighting conditions.
The photo below is an example how the color temperature affects an image. The image was filmed under natural sunlight, notice the unsightly blue color cast when the color temperature is incorrectly matched to 3200K.
Hopefully this helps shed a little light on the basics of color temperature. There are of course exception to this rule, but remember make sure that all light sources in a shot are color matched to either daylight or tungsten as well as the white balance setting on your camera matches your light sources to produce the most accurate colors in an image.