Canon RF-S3.9 mm F3.5 STM DUAL FISHEYE Instructions Manual page 18

Filters (Sold separately)
Filter
Filter cover
Rear filter holder
2
After attaching the filter to the
rear filter holder, attach the filter
cover to the rear filter holder
mounting thread.
Image ghosting may occur as a result of using a filter. Take care to avoid getting dirt or scratches on the filter.
z
Attachment position mark
Rear filter holder index
3
Match up the rear filter holder index and the
attachment position mark on the lens, and turn
the rear filter holder clockwise until it reaches
the stop position mark.
Removal is the reverse of attaching.
z
Stop position mark
Rear filter holder index
ENG-17