Flickering LED lights?

[Joerg Polzfusz]

Hi!

Do you also have problems with flickering LED lights? Some of them don’t seem to cause any flicker, while others flicker like hell (depending on the frame rate - the linked video was shot in „slo mo“ with an iPhone - most likely at 120fps).

Do you know how to avoid this?

Jörg

[Nicolas POISSON]

Some LEDs are sync'ed on the mains frequency. It might be possible to get rid of the flickering using adequate frame rate and shutter speed.

Some LEDs are controlled by PWM dimmers, that might be rather low-frequency of any value. I encountered 216Hz, 490Hz, 980Hz... The PWM frequency may vary slightly from one sample to another one (like one at 981Hz, the other one at 984Hz). It might not cause flickering, but bands appear on the image. There is almost nothing to do in such cases, except replacing the dimmer with a high frequency one. The higher the frame rate you want to shoot, the higher the PWM frequency should be. For 24, 25... up to 60 fps, a PWM frequency of 2kHz is an absolute minimum, 5-8kHz might be safer. If you want to shoot high frame rate, it is advised to have PWM frequency of 25kHz or higher.

[Joerg Polzfusz]

Changing the shutter speed helps to remove this effect (frame rate is more or less fixed in this special case). Thanks!

It looks like these LEDs are flickering at the mains’ 50Hz. It seems that only a very simple rectifier is integrated. ?

At least, the problem only occurs in the kitchen where we had use cheaper „no name“ LEDs to replace the halogen lamps (40W G9). That’s because -in that shop- the other Chinese LEDs with „known brandnames“ would have been to bulky or would have only been equivalent to 30W.

All other rooms are also equipped with LEDs, but from LEDvance, Philips or Samsung. And they don’t seem to cause any problems at my „usual frame rates“. ? The strange thing is that none of the LEDs state their „flicker-frequency“ on the box. ?

I wonder if I will run into the same problem in other places, e.g. when shooting the Christmas activities in my relatives‘ households. ?

 

[Stephen Sanchez]

Shutter on the camera side is the best value to adjust. We'd all prefer to change the fixture, but if that's not possible, at very least walk down on your shutter.

The Sony camera's I've shot with allow you to change your shutter on a frequency level. FX9 and FX6 call this "ECS mode." Venice allows something similar in the shutter menu by switching to Cont. (continuous). I'd have to do this to sync to LCDs on alarm clocks, oven screens and other electronics.