ExplainerTools

Short · Cameras

Why do LED lights flicker on camera?

Many LEDs pulse with the mains power, about 100 or 120 times a second. A phone that reads one row at a time catches some rows on and some off, unless the exposure spans a whole pulse.

Try it yourself

Opens Flicker Lab. Change the same thing yourself.

Narrated · 33 seconds · captions includedDownload the film

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Transcript

Why do LED lights flicker on camera? Many LEDs aren't steady. They pulse with the power from the wall, often a hundred or a hundred and twenty times a second, too fast for your eyes. Your phone reads each frame one row at a time, so some rows catch the light on, and some catch it off. Dark bands. Now slow the shutter to match one full pulse. Every row now catches a whole flash, and the bands disappear. Follow to see how the world works.