Rolling Shutter Artefact
Distortion caused by a sensor being read out progressively, so different parts of the frame record at slightly different times.
Measured in
ms
In depth
Because the top of the frame is captured before the bottom, anything moving fast is recorded in different positions on different rows. Vertical lines lean during a pan, propellers bend into curves, and flash illuminates only a band. The severity depends entirely on readout speed, which is why stacked sensors have largely solved it.
Examples in practice
A guitarist's strumming hand appears bent and stretched when shot with electronic shutter on a slow-readout sensor.