Greetings,
This is a contact canon situation. My Canon > create a support case and plan to send the camera in to be cleaned and inspected. The lens is fixed and is not removeable by an end user. There are ND filters behind it. This is not something I recommend you try to take on. There are too many things which might go wrong.
~Rick
Bay Area - CA
~R5 C (1.0.7.1) ~RF Trinity, ~RF 100 Macro, ~RF 100~400, ~RF 100~500, ~RF 200-800 +RF 1.4x TC, BG-R10, 430EX III-RT ~DxO PhotoLab Elite ~DaVinci Resolve Studio ~ImageClass MF644Cdw/MF656Cdw ~Pixel 8 ~CarePaks Are Worth It
