Pedro Sandrini, unsplash.com
When I first started getting involved in church tech, and even when I was working as a full-time church technical director, I had never heard of the lighting phrase “color temperature.” Back then, not many churches were doing video, and the only real lighting option for the vast majority of churches was your basic tungsten theatrical lighting fixture. It was what it was—what the color temperature of those fixtures were didn’t really matter because it was the only thing available.
Skip forward a few years, and now many churches are doing video, and light sources vary quite a bit. The traditional tungsten fixtures are still in widespread use, but there are now also LED light sources and arc-source moving lights in common use. And video is now the norm in the church as well, either in capturing video with a camera, or having video displays on stage. This means that color temperature now matters, and should be understood by church lighting and video techs.
So, what is color temperature?
Color temperature is basically the color of white. And no, white isn’t always white. Different types of light sources have a different color of white.
The sun is our primary reference for what white light is. However, if you light a candle at night and put it next to the same white surface that the sun was shining on during the day, you’ll realize that “white” from a candle is a yellow-orange. Your brain still sees that surface as white, because it implicitly understands that the light source is a different color. But when you make yourself analyze it, white is really yellow.
Likewise, the white from an arc-source moving light is actually rather blue, which makes its version of white feel very cold and harsh. Again, your brain sees it as white, but there’s a lot more blue in it than sunlight.
This attribute of white light is called color temperature because it’s based on the temperature that a theoretically ideal black body object needs to be at to emit that color of light. (Don’t worry about what an ideal black body object it is—that’s not the important part of our discussion.) The temperature is measured in degrees Kelvin, which is the Celsius measurement system but where 0 degrees is absolute zero (or -273.15 degrees Celsius).
So, the color temperature of a standard tungsten light fixture (be it a home lightbulb or a theatrical fixture) is about 3,200K. Daylight from the sun is about 5,200K. A fluorescent lamp is around 4,200K (with a touch of green added in). Arc source lighting is between 6,000K and 8,000K depending on the lamp. The main variation in the color is how much blue is in the light.
And why should you care?
Mixed color temperature lighting can give things an odd look. If you have a lot of daylight from windows in your auditorium or sanctuary and you use tungsten lighting to augment the light on stage, some things may look off. If your brain is primarily registering daylight for the color temperature, parts of the stage that are lit primarily with tungsten lighting are going to appear extra yellowy-orange. But, that’s not the main issue.
Where color temperature really affects us is with video and photography. Video cameras don’t have the range of color processing that our eye has, and color temperature variations in the scene they are capturing are hugely exaggerated.
Where color temperature really affects us is with video and photography. Video cameras don’t have the range of color processing that our eye has, and color temperature variations in the scene they are capturing are hugely exaggerated. You’ve all seen this: the interior photo in a room with windows, where everything outside of the windows looks great but inside the people are all yellow. Or visa-versa—the interior looks normal, but everything outside looks extremely blue. The video cameras capturing your service are going to have the same problem if your stage is getting some light from windows, but the rest from tungsten theatrical fixtures.
Modern LED lighting can often be adjusted to change their color temperature from the lighting console. You could adjust tthen closer to daylight for Sunday morning when light is streaming in through the windows, but have them be closer to tungsten at night for a warmer look. For lighting fixtures that can’t be adjusted internally, you can add a color-correction filter (or gel) to them to raise or lower their color temperature. For example, we’re adding a couple new LED followspots to a local Christian youth theater facility for which I volunteer. The LED light engines in these spots have a native color temperature of about 6,000K. They have a “warm white” setting, but that only brings it down to around 4,600K, which still looks very harsh with our tungsten stage fixtures.
I bought a sheet of Rosco 1/4 CTO gel and added this to the gel holder at the front of the fixture. CTO stands for Color Temperature Orange, and is used to bring a daylight source down to a tungsten color temperature; the 1/4 means that it is at ¼ the strength needed to bring a daylight source all the way to tungsten. This, combined with the internal “warm white” setting, brings us to around 3,600K. This is still a little more blue than the tungsten lighting, but the difference makes it stand out a little without being harsh, which I like.
Similarly, there are color temperature blue (CTB) gels that correct tungsten lighting to be closer to daylight.
Incorrect or mixed color temperature lighting does make a difference. It may not be blatantly obvious to a lot of people, but it makes the room feel “off,” and anytime something feels “off” to people, they are somewhat distracted or unsettled. Paying attention to color temperatures will improve your environment and especially your video.
