Canon EOS R3 Advanced User's Manual page 249

Digital Lens Optimizer
Various aberrations from lens optical characteristics can be corrected, along with diffraction
and low-pass filter-induced loss of resolution.
If [Correction data not available] or [
use EOS Utility to add the lens correction data to the camera. For details, refer to the EOS
Utility Instruction Manual.
Caution
Image processing after you shoot takes longer when set to [High] (which causes
the access lamp to be illuminated longer).
Maximum burst is lower with [High]. Image recording to the card also takes longer.
Depending on shooting conditions, noise may be intensified together with the
effects of correction. Image edges may also be emphasized. Adjust Picture Style
sharpness or set [Digital Lens Optimizer] to [Disable] as needed before shooting.
The higher the ISO speed, the lower the amount of correction will be.
For movie recording, [Digital Lens Optimizer] will not appear. (Correction is not
possible.)
The effect of Digital Lens Optimizer cannot be checked on the screen at the time of
shooting.
Note
With [Digital Lens Optimizer] set to [Standard] or [High], [Chromatic aberr corr]
and [Diffraction correction] are not displayed, but they are both set to [Enable] for
shooting.
] is displayed by [Digital Lens Optimizer], you can
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