Is it a UV filter? Probably the universe speaking to you. I only use polarizers or ND filters.
Yeah, UV
Yes, you read that right. The filter fell right off my lens while out shooting, bouncing once and landing by some poorly scraped-up dog crap.
How do I clean/sanitise it without destroying the coatings? Is it done for?
Is it a UV filter? Probably the universe speaking to you. I only use polarizers or ND filters.
Yeah, UV
Soap and water.
I mean this is 100% the correct answer.
Forever unclean. Bin it
How would you clean your fingers? Do it the same way.
if it's just the filter, I'd rinse it gently with a clean water first then use proper lens cleaning solution and a microfiber cloth. don't scrub while there's still debris on it
I keep a big box of disposable Zeiss lens wipes for my lenses.