A better name for this feature should have been ‘vignette removal’ but since the marketing department does not want to admit that their lenses vignette, they decided to use a more sophisticated name.

Basically, when enabled, it uses hardware algorithm to compensate for the underexposure in the corners.

There is a debate among video shooters if they should or not use the feature. While fixing vignettes is easy to do in post-production with still images shot in RAW format, the compressed format of video makes it much harder to do. On the other hand, letting the camera CPU decides how the image should be fixed can create issues in some special cases.

Note regarding stills

If you are shooting JPEG and activate the feature, the correction will be automatically applied. If you are shooting RAW, the file will store in its metadata that you requested the correction but it will only be applied if you use a RAW interpreter that can process this metadata, such as Canon Digital Photo Professional.

What I do

I keep it off for both stills and video and use L lenses to minimize vignetting.

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