Canon EOS 5D MARK IV Instruction Manual page 215

3 Correction of Lens Aberrations due to Optical CharacteristicsN
Lens Correction Data
The lens correction data for lens aberration corrections is registered
(stored) in the camera. With [Enable] selected, the peripheral
illumination correction, distortion correction, Digital Lens Optimizer,
chromatic aberration correction, and diffraction correction will be
applied automatically.
With EOS Utility (EOS software, p.598), you can check which lenses
have their correction data registered in the camera. You can also
register the correction data for unregistered lenses. For details, refer to
the EOS Utility Instruction Manual (p.600).
For lenses incorporating the correction data, it is not necessary to
register the correction data to the camera.
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