I just purchased some used camera filters, including an FL-D filter with what appears to be soap scum on the glass. I have some cleaning fluid and q-tips, but it doesn't seem to be working well. I also have lens tissues. Any suggestions as to what I should be doing, or is it a lost cause?
Picking nits here, but possible "soap scum" isn't exactly mineral deposits.
Though I do agree on the use of vinegar on the latter...
For some shock value, I have put filters, lens elements and various mechanical components through my dishwasher (gentlest cycle) with excellent results. YMMV!!