Some light sources, including mercury-vapor and fluorescent lamps, cycle on and off (flicker) at the same frequency as the AC current that powers them (generally 50 or 60 Hz). This flicker may appear during live view and movie recording and in recorded movies as cyclical bands wider than the “lines”. These bands are described as “flicker” when they appear to move rapidly in a vertical direction.

The movie linked below shows “flicker” (lines moving rapidly in a vertical direction).

http://www. Vimeo. Com/1794813

http://www. Vimeo. Com/1958492