There are traditionally two important numbers you should know by heart: 3200K which is the temperature of tungsten lighting and 5600K which is the temperature of sunlight at midday.

Almost all cameras have the ability to set a custom white balance using a grey card or white card. This is done by filling the frame with something gray or white and pressing the white balance button which zeroes the values so that color neutral.

For much better control, professional cameras also have the ability to dial in a specific number for your white balance. This is great for dialing in your look - if you want more of a warmer tone, push the color temperature higher, more cool, push the temperature lower.

And If you’re shooting with a camera that shoots in RAW format, you can save your white balance decisions until post.

A common color temperature problem that pops up is when you have competing light sources with different color temperatures - like you’re shooting indoors near a window and using tungsten light.

If you white balance to 5600K, the indoor lights will look orange. If you balance to 3200K, the light from the window will look blue. To get them to match you can use gels - either cover the entire window with CTO (orange) gel or just cover the light with CTB gel.

Corrected with CTB on light and camera set to 5600K

Of course there’s no reason why you can’t use that disparity for artistic effect.

It’s also worth mentioning here that the dimming of tungsten lights will lower their color temperature and make them look warmer. After all, the filament isn’t getting the same current therefore it’s not burning as hotly so by Planck’s law, they will be a lower color temperature.

Now there’s no need to adhere rigidly to any of these numbers. Just because we’re shooting under tungsten lighting doesn’t mean we have to set the camera to 3200K. Or that we can’t blend different color temperatures in a single shot and mix cold outdoor light with warm interior light. But understanding the mechanism of color temperature will help you solve artistic challenges when you’re on set.