Canon EOS-1D X Mark III Advanced User's Manual page 485

3.
Set the cropping frame.
The image area within the cropping frame will be cropped.
Resizing the cropping frame size
Turn the <
cropping frame, the more magnified the cropped image will look.
Changing the cropping frame aspect ratio and orientation
Turn the <
orientation.
Moving the cropping frame
Use <
Correcting tilt
You can correct image tilt by ±10°. Press the <
checking tilt relative to the grid, turn the <
or tap the left or right arrow (in 0.5° increments) in the upper left of the
screen to correct tilt. After completing the tilt correction, press <
4.
Check the image area to be cropped.
Press the <
> dial to resize the cropping frame size. The smaller the
> dial to change the cropping frame aspect ratio and
> to move the cropping frame vertically or horizontally.
> button. The image area to crop is displayed.
485
> button. While
> dial (in 0.1° increments)
>.