Canon EOS R5 C VR Creator Kit with RF 5.2mm f/2.8 Dual Fisheye Lens - Manual (Page 205)

3.
Select a setting.
Confirm that the name of the attached lens and (except for diffraction
correction) [
Correction data available ] are displayed.
If [ Correction data not available ] or [ ] is displayed, see Digital Lens
Optimizer .
Caution
Not available when shooting multiple exposures.
Peripheral Illumination Correction
Vignetting (dark image corners) can be corrected.
Caution
Depending on shooting conditions, noise may appear on the image periphery.
The higher the ISO speed, the lower the amount of correction will be.
Note
The amount of correction applied will be lower than the maximum correction
amount applied with Digital Photo Professional (EOS software).
Peripheral illumination is corrected automatically in [
] mode when correction
data is registered on the camera.
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