Canon EOS-1D X Mark III DSLR Camera (Body Only) - Manual (Page 140)

2.
Set the white balance correction.
Sample setting: A2, G1
Use < > to move the “■” mark on the screen to your preferred
position.
B is for blue, A for amber, M for magenta, and G for green. White
balance is corrected in the direction you move the mark.
On the right of the screen, [ Shift ] indicates the direction and correction
amount, respectively.
Pressing the < > button will cancel all the [ WB Shift/Bkt. ] settings.
Press < > to exit the setting.
Note
< > is displayed on the top LCD panel during white balance correction.
You can set the camera to display < > in the viewfinder to notify you if white
balance has been corrected ( ).
One level of the blue/amber correction is equivalent to approx. 5 mireds of a color
temperature conversion filter. (Mired: Unit of measure for color temperature used to
indicate values such as the density of a color temperature conversion filter.)
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