Canon EOS R3 Advanced User's Manual page 230

2.
Set the white balance correction.
Sample setting: A2, G1
Use <
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.
The direction and amount of correction are indicated in the upper right
of the screen.
Pressing the <
Press <
Note
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.)
> to move the "■" mark on the screen to your preferred
> button will cancel all the [WB Shift/Bkt.] settings.
> to exit the setting.
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