Why Do Screens Look Weird When Filmed With a Camera?

Ever tried to take a photo or video of your TV, computer, or phone screen, only to end up with strange flickers, rolling lines, or weird color patterns? You’re not alone, and there’s a good reason this happens.

It’s All About Refresh Rates

Screens don’t display a single static image. Instead, they refresh the image many times per second, typically 60, 120, or even 240 times. This is known as the refresh rate, measured in hertz (Hz). But your camera has its own timing system, called the frame rate, and when those two rates don’t match, strange things happen.

Mismatched Timings = Visual Glitches

Think of a screen refreshing like blinking lights. If your camera catches the screen in between those blinks, you’ll see dark bands or flickers. It’s not that the screen is malfunctioning, it’s just that your camera is capturing moments your eyes can’t normally perceive.

Moiré Patterns: The Weird Rainbow Effect

Moiré patterns happen when two repetitive patterns overlap in just the wrong way. Many screens, especially LCDs and OLEDs, are made of tightly packed grids of pixels. Your camera sensor also has its own grid of pixels. When these two grids don’t line up perfectly, they create interference—producing swirling rainbow patterns or wavy lines on your recording.

These moiré artifacts are more likely when:

• You’re zoomed in on a high-resolution screen.
• The screen’s pixel pitch (density) closely matches your camera sensor’s pixel arrangement.
• You’re recording printed screens (like e-ink or certain LED signs).

Rolling Shutter Effects

Most phone and DSLR cameras use something called a rolling shutter, which records an image line by line from top to bottom. If the screen changes while the camera is still capturing, it creates rolling lines or partial images, especially noticeable with fast-refreshing LED or OLED screens.

PWM and Brightness Flicker

Some screens use a technique called pulse-width modulation (PWM) to control brightness. It rapidly turns pixels on and off to dim the display. This is invisible to the naked eye, but a camera might pick it up as flickering.

Why It Varies by Device

You might notice this effect more with certain screens or phones. That’s because:

• Different screens have different refresh technologies.
• Newer cameras with higher frame rates or global shutters can reduce or eliminate the effect.
• Shooting under artificial lighting (like fluorescent bulbs) can compound the issue due to their own flickering behavior.

How to Fix or Reduce It

• Adjust your camera’s shutter speed or frame rate to better sync with the screen’s refresh rate (e.g., 1/60 sec for 60Hz screens).
• Use manual settings if your device allows it, auto mode often makes things worse.
• Try a different angle or distance, sometimes even a slight change helps.
• Use screen recording software if you just want to capture what’s on the screen, glitch-free.

So, the next time your camera struggles to capture a clean shot of a screen, just know it’s all about timing, and some invisible tech magic.