So What is Light Temperature (Light Part 1)

December 30, 2015  •  1 Comment

Photography is all about light and controlling that light has caused frustration for photographers since the first photograph, taken in the early-1800s…an eight-hour exposure taken by Joseph Nicéphore Niépce in 1826 outside his Chalon (France) workshop window. Cameras and photography have come a long way since that first fuzzy, grainy image. Today, images are captured in fractions of a second and immediately converted to digital information that can be printed at home, or sent virtually anywhere in the world. You can view them on computer monitors, print them on digital printers, incorporated into video presentations, and so on.

It wouldn’t be a problem if we could control the sun, but that’s out of the question. To find a solution, first we need to know more about light itself. The sun isn’t the only light source. What about all those other light sources - house lamps, streetlights, campfires, or candles?

Two things happen when an object moves from cold to hot. A big chunk of iron bar gives off no heat or light. As it is heated, the chunk of iron starts glowing red, then orange, then yellow, then white, and on up to blue. The temperature change is measured in degrees Kelvin. Photographers use that same temperature scale to identify the “light temperature” of a scene being photographed. A representation of the Kelvin scale showing radiant heat (bottom numbers) and corresponding light description (top row).

Note:

This chart is not law. It is only a representation of how the color of light changes in comparison to the degree Kelvin.

In the old film days, color film was designed for daylight. Various densities of warming or cooling filters could be attached to the front of a camera lens to compensate for the color of the light falling on your subject. It took a lot of trial and error to know which filter to use and that meant developing the film before you realize that you needed a cooling filter and you used a warming filter. Digital cameras have made color correction far easier.

Color film was designed for specific light sources....daylight, tungsten lamps, etc. If the light was different than what the film was designed for, such as using tungsten film in daylight film, the color of the image would be distorted without the use of special filters designed to shift the color temperature. Film photographers either limited where they shot or carried an array of filters to compensate for incandescent lights, tungsten lamps, the different types of fluorescent lights (tubes, CFLs, etc.), mid-day sun, etc. LED light was not a problem then. Compensating for the different types of light was difficult when printing the images because not every shot on a roll of film was taken at the same location under the same lighting conditions.

The good news is today’s digital cameras, even inexpensive point-n-shoots, automatically compensate for changes in color temperature through a concept called “white balance.” White balance is a term from the film industry where a white sheet of paper was used to set the “white balance” of a video camera prior to shooting. When the white balance was set, the sheet of paper would appear white in the final image. If the white balance was not set properly, the sheet of paper would have a color overcast as would all the video. Most of the time, the color overcast was virtually impossible to remove completely.

Most digital cameras have the ability to set the white balance automatically without the need to hang a white sheet of paper in front of the lens. Setting the white balance to “Auto” is sufficient, especially if you are shooting under a variety of lighting conditions and do not intend to hang your images in an art gallery. However, experiment with the other color settings (daylight, shade, cloudy/sunset, tungsten, white fluorescent, or flash) to see how each affects the final image. For example, choose “Cloudy/Sunset” the next time you try to shoot a Lake Michigan sunset, or “Daylight” the next time you shoot outside on a sunny day.

Typically, digital cameras offer a number of color corrections in addition to a manual white balance control (AWB). Together, they help the camera see "white" regardless of the light source. In most cases, these settings are:

The two images of the dancer statue were both shot with subdued daylight filtering in and large tungsten lamp chandeliers. The difference is the one on the left had the white balance set to “Auto,” and the one on the right had it set to “Tungsten.” Even though the sun was the dominant light, by compensating for the tungsten lamps the overall image is closer to the true color.


Comments

Trish Lora(non-registered)
Very interesting!
No comments posted.
Loading...

Archive
January February March April May June July August September October (1) November (1) December (1)
January (1) February March April May June July August September October November December
January February March April May June July August September October November December