Minimum PWM Frequency to Avoid LED Video Flicker.

[Justin Hullinger]

Anybody have thoughts on the minimum PWM dimming frequency an LED light needs to have to avoid on camera flickering? I've heard answers ranging from 1000 to 3000 as well as 20 times the frame rate.

The question is in regards to the Martin rush par which has a PWM frequency of 2000 hz. Using a flicker calculator on David Satz dot com it seems I would get a flicker of 0.01 of an F-stop. I am not sure that difference would be perceptible on camera but it seems like it could appear as a soft pulsing. Chauvet seems to use 600hz. Some older Elation fixtures measured at 300 hz but newer ones are probably hight

Cameras are at a 180 degree shutter, 1/60th frame rate and 30 FPS.

 

[Ford]

Usually, you want to be at a multiple of 50 and 60. This is not true of every camera, but is true for the majority.
However, every camera is different, so having variable PWM allows you to adjust to your camera, instead of adjusting your camera to your lights.

Finally, the higher the PWM, typically the worse your dimming performance is. So, just turning them all up to 25khz may be good on camera, but not great for your live audience.