Lighting
Flicker / PWM Frequency
01 — Definition
LED fixtures set their brightness by PWM, switching the LEDs on and off very fast — and it is that PWM frequency that decides whether the flicker shows on camera. Below 100 Hz it appears as banding on most cameras; between 100 and 2000 Hz it depends on the camera; above 3000 Hz it is generally safe for any broadcast. Quality fixtures state their PWM frequency, cheap ones keep quiet about it.
02 — In the field
The symptom of a low PWM frequency on camera: horizontal bands scrolling through the image. The fix: change the fixture, or set the camera shutter angle to line up with the flicker frequency.