Imagine this: you want to record a video in a well-lit room. You take out your cam or your phone, take a look at the screen and suddenly notice a weird effect. All the LED lights flicker. For the naked eye, the lighting appears to be perfectly normal, while your cam is picking up this annoying flickering. Why do LED lights flicker on camera? Is there a way to fix it? Read on to find out.
How do cameras work?
Why do LED lights flicker on cams? Is this a bad camera or light source problem? Surprisingly, it’s neither. The flicker is most noticeable on the top-notch cameras that record smoother and better videos. How can that be?
To answer this question, we need to go back to the basics and understand how cameras work and what’s more important how humans perceive visual information in the first place.
The thing is that cameras don’t record one continuous video. What they do is take dozens of separate photos in short succession. When we’re watching a video or a movie our brains can’t process the visual information fast enough.
The photos or rather frames of the video footage blend which causes us to see smooth, continuous movement instead of a series of individual pictures.
For a long time, most cameras took 24 pictures (or frames) per second. That was quite enough for most people. Go any lower than that and the objects in the footage will start to move sharply and laggy.
You can certainly go higher than that. Most modern cameras take thirty frames per second. Professional cameras can have an even much higher frame rate‘ Expensive action cameras have a frame rate of 120 frames per second (FPS) or higher.
Professional slow-motion cameras have an FPS of several hundred or even thousands of FPS. This allows them to capture even the slightest and briefest movements.
The cause of the flickering effect
This is all very fascinating, of course, but what does it have to do with the flickering lights?
The thing is that LED lights do not shine continuously either. Because of the alternating current the intensity of the light grows and drops constantly. LED lights turn on and off, again and again, many times every second, i. e. they flicker.
However human eye can’t detect this flickering for the same reason we don’t see that all the videos are nothing but a series of separate pictures.
At the same time, if a camera is good enough and has a high enough frame rate it can see LEDs flicker. What happens is since these cameras take so many separate photos per second on some of these photos the LED bulb is going to be off.
LED lights flickering on videos might be annoying as it is. However, did you know that it can cause another kind of distortion called the ‘strobe effect’?
The strobe effect is a phenomenon when moving moving objects appear to be frozen in time. Essentially, flickering lights might turn your video into an unwatchable slide show. This is why it is so important to know how to stop LED light flickering.
Stopping LED light flickering
Is it possible to fix flickering lights? Yes and no.
Sadly, there’s no way to stop light flickering in an already finished video. The only way you can deal with this problem is to prevent it from arising in the first place. Luckily, there are many methods you can do that.
Adjusting shutter speed
The most logical solution would be to adjust the shutter speed. What is the shutter speed?
This term comes from the times when cameras used a real physical barrier, or ‘shutter’ to stop the light energy from hitting the film. Every time the shutter opened the light would enter the camera and the picture would be imprinted on the film.
By changing the shutter speed you would change the number of times the shutter opened and closed in one second, i. e. you would change the number of frames per second.
At the same time, keep in mind that these terms are not interchangeable. To calculate the shutter speed, you need to double the frame rate. Let me explain.
Suppose, your desired frame rate is 30 FPS. This means that the shutter speed should be 1/60th of a second. 25 FPS is 1/50, 50 FPS is 1/100, etc.
But what shutter speed should you select to prevent flicker? It depends on the frequency of the alternating current in your area. Most countries in the world use 50 Hertz current, while the US prefers 60 Hertz.
For the 50 Hz AC, you can choose any of the following speeds: 1/100, 1/50, 1/33, 1/25.
The optimal shutter speeds for the US are 1/120, 1/60, 1/30, 1/24.
The shutter speed adjusted to the correct figure should stop the flicker. If you don’t feel like delving into the technical details, camera manufacturers have got you covered.
The chances are that your camera can automatically adjust the speed for different AC frequencies. Just go to your cam’s settings and look for an option called Anti-banding mode. Tap on it and choose between the two frequencies: 60 Hz for the US, and 50 Hz for the rest of the world. Your cam should do the rest.
Incandescent light bulb
As you could’ve noticed the flickering effect is only there if you use LED lights. LED bulbs may be energy efficient and bright but in a case like that they might be inferior to the good old incandescent bulbs. Why is that?
The incandescent bulbs flicker too but their glowing hot filament can’t cool down fast enough between the flickers. That’s why the lighting they provide is more stable than that of an LED light.
A similar solution would be to use a bigger LED light. Since the big LED lights run hotter their diode will also need a longer time to cool down, thus it will shine more steadily.
Using DC power supply
You can also prevent LED lights flicker by changing the power supply. There are a couple of ways you can do that.
The first method is to power your LED light source with a battery.
In contrast to the energy network, batteries provide Direct Current (DC) instead of alternating one. Because of that, LEDs powered by a battery will not flicker at all.
If the flickering effect is still there, it might mean that your LEDs are connected to pulse width modulation. Pulse width modulation (PWM) helps to regulate the brightness of an LED light source. PWM is found in smart bulbs and daytime running lights in your car.
Finally, you can opt for the natural light. Sun is pretty much the only stable light source, provided there are no clouds, of course. Shooting a video outside might be tricky but with enough experience, you will be able to master this art.
The Impact of Multiple Frames and Dim Lights
While adjusting the shutter speed remains a fundamental solution, there’s more to the story behind flickering LED lights on camera. Consider the influence of multiple frames captured per second. These cameras, with their high frame rates, tend to capture nuances that the human eye simply glosses over. As LEDs intermittently dim away from the light source due to alternating current, the camera’s rapid succession of frames catches these fluctuations, revealing the flickering effect unseen by the naked eye.
In a video recording, this flickering presents as a series of dim moments in the LED light’s cycle. The constant flicker on the camera stems from its ability to capture instances when the LED is momentarily off. This discrepancy between what the human eye perceives and what the camera detects leads to an unwanted visual disturbance, evident as flickering in the video feed. Hence, despite the smooth appearance to the human observer, these lights flicker in a manner unseen but glaringly evident through the lens of a high-quality camera.
Addressing Flicker in Video Footage
The flickering of LED lights, while invisible to our eyes, poses a challenge in videography, causing disruptions like the strobe effect. However, solutions exist to mitigate this issue. Apart from adjusting shutter speed, altering the power supply or opting for natural light can effectively reduce or eliminate LED light flickering in recorded videos.
Consider utilizing a DC power supply, as it eliminates the flicker associated with alternating current. By powering LED sources with batteries or through a direct current connection, the fluctuation caused by alternating current can be circumvented. Additionally, employing larger LED lights extends the cooling time between flickers, promoting more consistent illumination and reducing the discernible flicker in video recordings.
Moreover, embracing natural light sources, like the sun, offers a stable alternative without flickering issues. Although challenging, mastering the art of capturing videos in natural light environments provides an effective workaround to the flickering problem posed by artificial LED lighting. By exploring these methods, one can enhance video quality and eliminate the distracting effects of LED light flickering in recorded footage.
So why do artificial lights flicker on camera? The answer is that the lights flicker all the time, we just can’t see it with the naked eye.
As opposed to the human eye, modern cameras can detect the slightest fluctuations of a light source. Luckily, the flickering effect might be avoided if you tweak the camera’s settings or change the light source.
Why do LED lights mess with cameras?
LEDs flicker constantly. We just can’t see it with our eyes. Cams, on the other hand, can detect the flicker.
Why is my iPhone camera flickering LED?
Flickering lights means that your iPhone’s FPS rate is unaligned with the AC that powers the lights. Go to the cam settings, and choose 50Hz option or 60Hz depending on what country you’re in.
Why do screens flicker on camera?
Usually, screens flicker if they have a low refresh rate. You can change the refresh rate in the settings of your PC.
Why do LEDs look different on camera?
LED bulbs flicker all the time because of the power current fluctuations. High-quality cameras or slow-motion cameras can detect the flicker while our eyes can’t.
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