Why Do Cameras Do This? | Rolling Shutter Explained - Smarter Every Day 172

Phone cameras contain a CMOS sensor (Complementary Metal-Oxide Semiconductor) that captures images differently than expected.

Instead of exposing the entire sensor at once like a traditional photo, the camera scans down the chip row by row to create images.

This scanning method creates rolling shutter artifacts that distort fast-moving objects into weird shapes on your phone's camera.

This scanning technique is called rolling shutter, and it's responsible for the strange visual effects you see in phone videos.

A flatbed scanner works similarly to a phone's rolling shutter, with a moving row of pixels scanning from top to bottom.

• When an object moves in the same direction as the scanning pixels, it gets stretched • When an object moves opposite to the scanning direction, it gets compressed

What you see in a rolling shutter image is actually a stack of several different moments in time, not a single frozen instant.

This layering of different time moments is what creates the strange distortions and unnatural shapes in fast-moving objects.

Over three years, whenever a phone and high-speed camera were available simultaneously, rolling shutter events were documented and manually simulated.

While filming in a turboprop plane over the Australian outback, rotating the phone revealed changing propeller patterns due to rolling shutter interactions.

The propeller patterns looked dramatically different depending on the direction the propeller was rotating relative to the rolling shutter scan.

During high-altitude flight lessons near Pike's Peak in Colorado, a head-on propeller video was finally captured on the tarmac.

The fidget spinner community discovered that bright outdoor lighting causes phone cameras to transform spinning fidget spinners into distorted shapes.

The transformed spinner appearance is called 'the thing,' resembling a Ninja Alien throwing star shape.

This effect combines rolling shutter with a small amount of aliasing, creating the unusual distorted appearance.

High-speed camera footage reveals the underlying map and motion patterns that create the weird visual distortion.

Getting rolling shutter effects to appear on mandolin and guitar strings required extensive trial and effort with collaborator Ben.

Guitar strings vibrate so quickly that standard high-speed cameras cannot capture the effect adequately.

Recording at 20,000 to 28,000 frames per second was necessary to capture sufficient detail for proper rolling shutter simulation.

When the proper frame rate was achieved, the rolling shutter effect on vibrating strings produced visually striking results.

A previously unknown rolling shutter effect was discovered: spinning coins display a swirl pattern on their edges when filmed with a phone.

This swirl pattern is caused by the rolling shutter effect interacting with the coin's rotation.

The effect became visible through the same high-speed camera and simulation techniques used for other rolling shutter demonstrations.

Rolling shutter artifacts appear in various rotating objects and fast-moving scenarios, not just propellers and fidget spinners.

Henry from MinutePhysics developed the After Effects technique used to simulate rolling shutter for the visualizations.

A behind-the-scenes video on the second channel features Henry and Destin discussing their production goals and technical approach.

Rolling shutter should not be confused with aliasing, which creates the wagon wheel effect seen in videos.

Understanding rolling shutter versus aliasing prevents common misconceptions about how camera artifacts are created.