I took a gamble and bought a used B+W Circular Polarizer off eBay. The filter looks great but the adjusting ring is a little bit sticky. Is there some way to lubricate this?
I dropped my CPL onto some rocks and it's a bit scratched up. There's no obvious effect in a (very cursory) look at the photos, but are there tests I can do to see if the damage has a visible effect?