Why Propellers Look Broken on Camera

Film a spinning propeller on your phone and it can look bent, broken, or melting.

Your eyes see a normal propeller, so why does the camera see something impossible?

Most phone sensors do not capture the whole scene in one instant. Instead they read the image one row of pixels at a time, sweeping from top to bottom. This is called a rolling shutter. The sweep is fast, usually a small fraction of a second, but it is not instant. For slow scenes you never notice. But if something moves fast during that sweep, like a propeller blade, it travels to a new position before the lower rows are even read. Each row captures the blade somewhere different, smearing it into a curve.

The same effect bends guitar strings, skews fast cars, and warps lightning. Pro cameras fix it with a global shutter that grabs every row at once.

Follow The Explainer Vault — because everything has an explanation.