Canon EOS 90D DSLR Camera with 18-135mm Lens - Manual (Page 571)

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Custom Function Setting Items
C.Fn III-3: Custom Controls
You can assign frequently used functions to camera buttons or dials
according to your preferences for easy operations.
1 Select a part of the bar.
2 Select a function to assign.

Press <
0
> to set it.
o With the screen in step 1 displayed, you can press the <
L
> button to revert
the Custom Control settings to their defaults. Customized operations are not
cleared if you select [Clear all Custom Func. (C.Fn)] .