The Color of Light

Okay, it’s time to go back to school for a few minutes. Yeah, I know we all wanted to do video so we could stay out of real school, but alas, this really is a craft and knowing this stuff does make a difference and seperates you from your uncle Eddie and his home movies.  Let’s talk a little bit about different colors of light, which measured on a degree scale, and how that translates into our world of creating video.

This is our buddy Lord Kelvin. In the mid 1800’s, he wanted to come up with a scale to measure the absolute tempurature of things. Lord Kelvin used black iron or steel as his reference as it was heated by a blacksmith. As steel is heated to a red color it is not hot enough to be shaped. As the metal continues to get hotter, it begins to turn a white hot and then goes further to even produce a blue-ish glow, which means it’s really hot. I know you’re reading a Blog about video but….stay with me Jimbo, stay with me!

The color of the black metal as it is heated is where we get our scale for the color tempurature of light, measured in degrees Kelvin. Go figure!

Red light is cooler than blue light? Before I knew the heated metal thing, my walnut sized thinker thought, “In my world something red …fire, is hotter than something blue … water.” Now aren’t you glad I’m not teaching your kids physics.

Here is a color tempurature spectrum and some common bench marks of light that we all use when working with video. Most lights used in video lighting are color balanced at 3200ºK. You can see further down the scale, towards red, is a 100 watt bulb that is in the lamp on your desk. When you are shooting a video scene with a lamp in it, the lamp usually looks more yellow or amber than your video lights, and now you know why. You may have noticed if you are trying to shoot video in a room with lots of sunlight from nearby windows, the light hitting your subject appears to be more blue. You can especially see the difference if you try and supplement the window light with your video lights. Your video lights will seem really yellow compared to the sunlight. The diagram further shows why subjects may seem a little washed out when you are shooting them in direct noonday sun and why a candle flame has that nice redish glow. Ain’t science cool!

Okay, how do we use this to make our buddy Lord Kelvin proud? Well, that’s for another entry.

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