Canon EOS-1D X Mark III DSLR Camera (Body Only) - Manual (Page 211)

Anti-Flicker Shooting
Uneven exposure and color may result if you shoot at fast shutter speeds under flickering
light sources such as fluorescent lights, due to uneven vertical exposure. Anti-flicker
shooting enables viewfinder shooting at moments when exposure and colors are less
affected by flickering.
1.
Select [ : Anti-flicker shoot.].
2.
Select [Enable].
3.
Take the picture.
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