He opened the edit to assemble an interview he had filmed that morning. The first shot of the man's face was warm and comfortable. The second, one question later, was cold and blue, as if it had been filmed on another day in another place.
Same room. Same chair. Ten minutes between the two shots, and a cloud passing the window.
He had done nothing wrong while filming. He had only let the camera decide the colour for itself, and it decided twice.
What colour temperature means
Every light has a colour, even the one we call white. That colour is measured as a number in kelvin: low numbers are orange, high numbers are blue. Which is the opposite of what most people expect.
These numbers are all you need to remember:
| Source | Roughly | Its colour |
|---|---|---|
| A candle | 1800 | strong orange |
| A warm household bulb | 2700 to 3000 | orange |
| A cool white bulb | 4000 | neutral, leaning blue |
| Midday sun | 5600 | neutral |
| An overcast day or shade | 7000 and up | blue |
White balance on your camera is how you tell it: "the light here is this colour, so make white look white." Give it a number lower than the truth and the picture turns blue; give it a higher one and the picture turns orange.
Why auto is the enemy in video
In stills, auto white balance is useful: each photo is its own decision, and you can correct it afterwards.
In video it is a problem, because the camera recalculates continuously. You are filming, someone in a red shirt walks through the frame, or you shift slightly so part of the window comes in, or a cloud passes, and the camera changes its mind. You see the result in the edit: colour sliding around inside a single shot, which is uglier than a wrong colour held steady.
The first and last rule: turn auto off and lock one value for the whole scene.
How to set it on location in thirty seconds
The accurate way: take out a sheet of white paper (or a grey card), fill the frame with it in the same light that will fall on the person, then use your camera's manual white balance option. The camera reads the paper, works out the number itself, and holds it.
The quick way: lock a number based on where you are.
- Outdoors in daylight: near 5600.
- In shade or on an overcast day: near 6500.
- Inside a home with warm bulbs: near 3200.
- Under cool white office lights: near 4300.
Then look at the person's face on the screen and move the number up or down until the skin looks natural. Skin is the most honest reference you have, because your eye knows what skin looks like and spots a fake instantly.
The third way: make the number deliberate rather than correct. Sunset is warm by nature, so "correcting" it fully kills the feeling. Push the number up a little to keep its orange.
The biggest mistake: two sources in one scene
This is the one thing the edit cannot fix, and it happens most in homes and offices.
The situation: you film in a room with a window (blue light) and a warm ceiling bulb. Set the balance for the window and the other side of the face goes orange; set it for the bulb and the window side goes blue. Any correction in the edit fixes one side and ruins the other, because both casts live in the same picture.
Three fixes, best first:
Pick one source. Switch the bulb off and use the window, or close the curtain and use the bulb. One source is cleaner than two at war, and it is part of arranging light, which we covered in lighting from a single source to three-point setups.
Match the two sources. If your LED panel can change colour, set it to the window's colour. If the room's bulbs can be changed, put cool white bulbs in place of the warm ones.
Make the difference deliberate. If the other source is far back in the background rather than on the face, it becomes a colour behind the subject that gives depth instead of a mistake. The trouble starts when both colours land on the same face.
The green cast nobody notices
Some fluorescent tubes and cheap bulbs add a green cast that no kelvin number will fix, because kelvin only moves between orange and blue.
That is why cameras and editing software have a second control called tint, moving between green and magenta. If the skin looks greenish, push it a little towards magenta. A small move is enough; too much makes the face look feverish.
Can I fix it in the edit?
Up to a point. A shot that is too warm or too cold is corrected with one move, provided it was filmed in a format that holds enough information. And a difference between two shots in the same interview is resolved by matching one to the other.
But three things the edit cannot fix: two colours in one picture, colour sliding inside a shot (the result of auto), and a picture with blown-out whites where no colour is left at all. The limits of grading, and what is worth working on, is the subject of the next article in this series.
If you are filming in low light, remember that noise makes correction harder, which we went through in filming in low light and at night. And if the camera numbers are not clear to you, start from the terminology and exposure triangle guide.
A checklist before every scene
Four things, half a minute:
Know the light sources in the room, and switch off the ones you do not need. Then turn auto white balance off and lock a number. Then look at the skin colour on the screen rather than the wall. Then film five seconds and review them before you carry on.
And if you come back another day to film the rest of the scene, write the number in a note on your phone. One line makes two days of footage look like one scene.