Canon RF 85mm F1.4 L VCM Instruction On Mounting And Use Manual page 20

Filters (Sold separately)
Attach the rear filter holder to the back of the lens.
4
Align the attachment position mark on the lens body with the index
on the rear filter holder.
5
Turn in the direction of the arrow until the rear filter holder index
aligns with the stop position mark on the lens body.
Attachment position mark
● Take some test shots before shooting to check that the filter is working
over the entire image.
● Check that the filter is correctly inserted before shooting.
● When the rear filter holder is attached to the lens body, ghosting may
occur depending on shooting conditions. When not using the rear filter,
remove the rear filter holder from the lens body.
● When removing the filter and rear filter holder, remove by reversing the
order of attaching.
Index Stop position mark
ENG-19