а вот что пишет сам производитель этих фильтров.
"To maintain the best optical performance of your filters, here is how we recommend cleaning (защитный фильтр) filters as well as all multi-coated optics.
Use high-quality disposable lens tissues and a liquid lens cleaner.
Make sure the glass surface has no dust or grit on it.
Take a lens tissue, fold it once or twice (depending on size), and place a couple drops of liquid lens cleaner on the tissue and wipe with the tissue in a circular pattern starting from the center and moving out to the edge.
Immediately follow the first tissue with a new dry tissue using the same pattern.
Warning: (защитный фильтр) does not recommend using the standard fabric "lens cleaning cloths" with any liquid because dust and grid can become trapped in the fibers and damage the lens or filter on subsequent uses.
Hoya filters are "hard-coated", meaning the metals and chemicals that make up the coating are applied in a furnace to bond them to the surface of the glass."