Canon PowerShot V10 Vlog Camera (Black) - Manual (Page 88)

Aspect Marker
If you will change the image aspect ratio when editing the recorded movie, you can display
aspect markers on the movie recording screen (during standby and recording) to be aware
of the final angle of view after editing.
1.
Select [ : Aspect marker].
2.
Select an option.
To hide the markers, select [ Off ].
Caution
Markers are not included in recorded movies.
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