Canon EOS R5 C VR Creator Kit with RF 5.2mm f/2.8 Dual Fisheye Lens - Manual (Page 206)

Distortion Correction
Distortion (image warping) can be corrected.
Caution
To correct distortion, the camera captures a narrower image area than the area
seen in viewfinder shooting, which crops the image a little and slightly lowers the
apparent resolution.
Applying distortion correction may change the angle of view slightly.
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