Rolling shutter distortion
From Wikicliki
From http://mpac.ee.ntu.edu.tw/Exhibition/rolling-shutter.php:
The electronic rolling shutter found in most low-end CMOS image sensors today collects the image data row by row, analogous to an open slit that scans over the image sequentially. Each row integrates the light when the slit passes over it. Therefore, the scanlines of the image are not exposed at the same time. This sensor architecture creates an objectionable geometric distortion, known as the rolling shutter effect, for moving objects.
