Cleaning Baader U filter - Recommendations please

[Adrian]

I have managed to put a large fingerprint in the middle of my Baader U filter. Can anyone tell me the best way to clean it please?

Thank you!

[OlDoinyo]

Place on table covered with clean paper towel. Wipe with microfiber cloth or lens cleaning tissue moistened with purified water or isopropanol.

[enricosavazzi]

Place on table covered with clean paper towel. Wipe with microfiber cloth or lens cleaning tissue moistened with purified water or isopropanol.

In addition, it works for me to start at the center of the filter and move in a spiral way toward the edge. Usually a dirt-mark remains where the last of the isopropanol or water evaporates, and it is better this mark is at the edge of the filter that in the center.

 

Also, the key word is "moistened", i.e. not dripping wet. And never let alcohol/water seep between the filter and its mount and retaining ring.

[Andrea B.]

A microfiber cloth needs to be really really clean to use on a coated filter. And be sure to blow/brush off any dust from the filter before cleaning just like you would do for a lens cleaning.

 

I've also used both Lens Pens and Purosol to clean filters. It always does bother me, however, that Purosol won't tell us what is in it. They simply say no alcohols or ammonias. Oh well.