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Why Do LED Lights Flicker On Video?

Take a look at the marvels of everyday technological inventions around you.

Your phone houses a dozen tools we would carry just a couple of decades ago, like cameras and calculators.

Sometimes, two tools created independently of each other can run into funny behavior when interacting.

These unexpected effects can also lead to more understanding of the science behind the working of the tools.

Today we will explore that science to ensure TikTokers look fine and dandy in their next video.

Sometimes an LED bulb, when viewed through a camera lens, flicks rapidly at regular intervals as if it is turning on and off.

LED bulbs turn on and off, so the flickering on video becomes more pronounced because the camera’s recording frames per second are unaligned with the frequency of electricity. This is called the ‘strobe effect.’

LED light’s flicker can be distracting and sometimes even enough to cause a slight slow-motion effect (like that caused by an actual strobe light). So let’s take a look at:

  • How to stop light flickering with your LED lights
  • The cause of the flickering effect when capturing video
  • Whether flickering refers to a bigger problem with your lights
  • Why incandescent bulbs appear flicker-free on video cameras

What Causes The Flickering Effect In The Video?

Empty photo studio interior on camera display

What if I tell you that LED lights flicker in real life and not just on video?

That’s exactly what happens. Our human eye cannot see the flickering of LEDs occurring in front of us, as it is too fast.

To understand why the LED flickers on video, let me explain the pure science behind it.

LEDs are powered by alternating current, AC, in which electrons in the electricity move in and out of the circuit in cycles.

A cycle of electrons per second is called Hertz (Hz). In 1 cycle or Hertz, the light bulb turns off twice as the electron alternates in and out.

In the US, electricity runs on 60 Hz, and in the rest of the world, it runs on 50 Hz. This means the bulb turns on and off between 100 to 120 times per second.

While the naked eye cannot see that flicker, seeing the LED through a camera lens makes the flickering obvious. We can see it happen on our screen as we record or playback a video.

Often, a camera opens and shuts its motion-capturing shutter faster than the speed of a flickering LED.

When we see the LED on our screen flickering black for a split second, the camera captures that image while the LED is turned off in its current cycle.

When the frequency of the camera’s frame rate per second (FPS) and the LEDs don’t quite match, the flicker becomes visible on the camera screen.

How To Stop LED Lights From Flickering On Camera?

camera with light in a shot

Since we know how the video camera picks up and shows flickering of LEDs, we can talk about how we can avoid this effect from getting picked up.

Undoubtedly, it can look pretty jarring and unsightly and greatly distract the viewer from your video content.

Depending on your setup, you might be unable to fully fix flickering lights. But even if you can’t completely eliminate the flickering effect, you can reduce it.

To stop light flickering, or to at the very least reduce it, you can do several things:

  • Reduce the camera’s recording frames per second, the FPS speed.
  • Adjust the shutter speed: At 60 Hz, you will need a frame rate of 30p with a shutter speed divisible by 60 – 1/60, 1/120, etc. At 50 Hz, you need 25 FPS at a shutter speed of 1/50 or 1/100.
  • Move closer or farther from the light, and adjust the aperture accordingly.
  • Increase or decrease the brightness of the lights.

All of these steps allow for the frequency of the AC current powering the LED to match as closely as possible to the FPS of the camera.

Even film restoration professionals face these flickering problems, and in fact, here you can read about how Peter Jackson and his team had to manually adjust the shutter speed of their cameras as they restored World War 1 footage that had a lot of flickering lights.

Keep in mind that usually, flicker occurs with LEDs connected to an AC supply, such as fairy lights.

Those LEDs that run on drivers that switch the current to direct current, or DC, don’t have this problem.

Some power supply drivers rectify the AC current from 50 or 60 Hz, increasing it up to 120 Hz, which becomes even hard for cameras to pick up, and fixes the problem.

If your LED lights flicker on a DC power supply, they might be hooked onto pulse width modulation (PWM) for dimming setups.

With PWM, the LED light again goes through periods of on-and-off cycles in the circuit that can be captured by the camera as it records.

That’s how it makes the LED appear dimmer. The LED light flickering is intentional because it means that when we perceive the light with our naked eye, it seems to be less bright.

But the unfortunate side effect is that it can appear on the video depending on your camera settings.

Of course, the best way to stop having flickering lights when shooting video is to avoid using an artificial light source on the screen altogether.

If you can use natural light, that will be best, though the light intensity may not be enough for your shot.

The other option is to position your light sources outside the shot so they still illuminate you/the space but can’t be seen on screen.

You can’t see the flickering effect with the ambient light produced by your LED lights, just on the bulbs themselves.

Should I Be Worried That LED Light Doesn’t Work Properly?

LED lights flickering on a video has nothing to do with the quality or the condition of the LED bulbs. You can rest assured that, in fact, your LED lights are working in the way they are supposed to.

Your only concern should be when you can actually see the LEDs flicker with your own eyes.

If you have a flickering LED light bulb that you can see with your own eye, that suggests a problem with the bulb or the circuitry.

Sometimes, when your eye cannot see the flicker, and yet the LED is not flickering fast enough, your brain can still pick up this unnatural light effect and cause headaches, nausea, and sight problems.

Do Incandescent Bulbs Flicker In Videos?

Incandescent bulbs also flicker at the same frequency as LED lights. But you would be hard-pressed to find a traditional bulb flickering on video!

This difference is due to the mechanics of how the two bulbs work.

While incandescent bulbs also run on AC current and turn on and off 100-120 times in a second, their filament wants to tell a different story.

Because the filament turns white-hot to emit heat, and as a by-product, light, the filament stays glowing hot long enough, even when the current is turned off.

The filament cannot heat up, and cool down to zero 120 times in one second!

So, the residual heat of the glowing hot filament makes it appear to be on. The overall effect is that incandescents don’t flicker on the video.

Final Words

With this nifty knowledge of electricity frequency and unaligned frames per second, you can confidently deal with any strobe effect in your videos.

Spend some time changing the camera setting, and with the shutter speed adjusted, you should be able to eliminate the LED lights’ flicker effect.

Have you seen any flickering LED lights on video set up with dimmers or on AC?

Does your camera or recording device have an adjustable shutter speed?

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Check out my free bulb picker and select the right bulb within few clicks.

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