Canon MARK IV User Manual (en)

 Custom White Balance
Photograph a solid-white object.
The plain, white object should fill the 
center spot metering circle.
Focus manually and set the standard 
exposure for the white object.
Any white balance mode may be set.
The Custom WB data will be 
To use the Custom WB, see  
“Selecting and Shooting with the 
Custom WB data” (p.76).
Spot metering circle
Custom WB data can also be registered as follows:
1. Press the <B> button and turn the <5> dial to select <O> 
2. Then turn the <6> dial to select the No. under which the Custom 
WB is to be registered.
3. Press the <A> button.
→ [ * ] will blink on the rear LCD panel. 
4. Follow step 4 above to photograph a solid-white object.
→ The Custom WB data will be registered under the selected No.
When a picture is taken, the registered Custom white balance will be 
If the exposure of the picture differs greatly from the standard exposure, 
a correct white balance might not be obtained. If [Correct WB may not 
be obtained with the selected image
] is displayed in step 4, go back to 
step 1 and try again.
The image captured in step 4 will not be recorded to the card.
Instead of a white object, an 18% gray card (commercially available) can 
produce a more accurate white balance.