Vignetting as Composition: RF 50mm f/1.2L Wide Open
The RF 50mm f/1.2L USM vignettes at f/1.2. This is not a defect to correct in post. Left uncorrected, it is a compositional tool that draws the eye toward the center of the frame and applies a graduated darkening to the corners. Canon’s in-camera lens correction and Lightroom’s lens profile will eliminate this automatically if you let them. You should consider not letting them.
Optical vignetting at the maximum aperture of a large-diameter lens is a physical consequence of the geometry: light arriving at the sensor from the edges at oblique angles is partially blocked by the lens barrel. At f/1.2, the RF 50mm drops approximately 2.5 stops at the extreme corners. By f/2.8, the vignetting is minimal. By f/4, it is effectively gone. The vignette is aperture-dependent — it appears and disappears as you work through your aperture range.
The compositional logic is identical to a physical vignette added in post, with one difference: optical vignetting has a specific character determined by the lens. It is not a uniform circular darkening. It follows the geometry of the optical design, producing an elliptical falloff that tends to feel organic rather than applied. When you see it in a finished image, you do not see a filter. You see the light of the scene.
The technique: disable automatic lens correction in-camera (Lens aberration correction > Peripheral illumination correction > off) and use the import without applying the Lightroom lens profile — or apply the profile and then reduce Vignetting back toward zero until the corner darkness feels balanced against the subject brightness. This gives you manual control over the degree of natural vignetting rather than the binary of fully corrected or uncorrected.
For portraits and environmental shots where the subject is centered or slightly off-center, the vignette creates a frame within the frame without cropping. The corners recede. The subject advances.
This costs you nothing. The lens is already doing it. Decide whether to keep it.