Reduce flicker and banding when shooting under fluorescent or mercury-vapor lighting during live view (0 Shooting in Live View) or movie recording (0 Recording Movies). Choose Auto to allow the camera to automatically choose the correct frequency, or manually match the frequency to that of the local AC power supply.
Flicker Reduction
If Auto fails to produce the desired results and you are unsure as to the frequency of the local power supply, test both 50 and 60 Hz options and choose the one that produces the best results. Flicker reduction may not produce the desired results if the subject is very bright, in which case you should select mode A or M and choose a smaller aperture (higher f-number) before starting live view. Note that flicker reduction is not available when On is selected for Movie settings > Manual movie settings (0 Movie Settings) in mode M.