During your next video filming day, as you watch the DigiNovations crew setting things up for on-location filming (turning on video cameras, tweaking lights, and lowering microphones into place), you might notice one of us take a seat in front of the camera, look into the lens and then hold up a piece of paper directly in front of our face. Nope, we're not goofing around.
We're setting white balance for the cameras, and we do it because not all light is created equal.
Remember that famous Pink Floyd album cover with the beam of white light hitting the prism and splitting off into the colors of the rainbow? Dark Side of the Moon is, of course, one of the most iconic album covers of all time. But it’s also an accurate depiction of how a beam of light that appears white is truly comprised of multiple wavelengths of different colors. In fact, most light we see is comprised of not just many colors, but all the colors (at least all that the human eye can see).
But here comes the tricky part: not all sources of light generate the color spectrum evenly. It’s subtle, but the lights in your house, office, and even sunlight, carry a compliment of color wavelengths that aren’t evenly distributed—so the rainbow isn’t symmetrical. The result is that the “white” light you see isn’t actually white at all.
Nearly all sources of light have a color cast, or “temperature” — the subtle tint of the light caused by the slightly uneven rainbow of colors in the light. Most indoor tungsten lights have a slightly orange or yellow color cast, flourescents are green, while sunlight and outdoor shade has a slightly blue hue.
You can see the different color temperatures in this image:
Now you might have never noticed the lamp light in your living room giving off any cast other than white, “normal” light. That’s because your brain works with your eyes to calibrate what you see, and to define what “normal” light looks like to you under different visual circumstances.
As advanced and powerful as our cameras are, they still need help figuring out what “normal” light color looks like. When the camera “sees” sunlight, it registers as slightly blue light. It’s the same with light from fluorescent bulbs in an office, which the camera “sees” as being a little green.
If we don't color balance under those light conditions, the video will have a color cast: blue for sunlight, green for fluorescent, and orange for tungsten.
So to film video without that color cast, we need to tell the camera how to compensate and make the light appear as true white. The way we do this is by setting the color temperature of the available light. By doing that, we're showing the camera what pure white “should” look like, so it can adjust itself and film without a color cast.
That’s where our white card comes in. When we sit in the hot seat on set and hold up a piece of white paper in front of our faces, we then point the camera at the white card, and adjust the color temperature so that the white card actually looks white. We are telling the camera how to balance itself so it films without a color cast.
Now that you know about color temperature, take a look around and see if you can spot some color casts. If you learn to see like a camera you’ll become much better at producing clean, realistic images and video. Your viewers will thank you for it.
And next time you see us with a white card in front of our faces on set, ask about the color temperature and white balance – we’re sure to be impressed with your knowledge!
Topics: Video Production