Hi fellow photographers, this question struck me as I was attempting to get a shot of the merlion while a gust blown my way and water went all over my filter. I just cleaned my filter after the previous shoot and I wonder will the coating of the filter be diminished after cleaning or rubbing after a period of time? With that in mind, how often do you clean your lens/lens filter in order to preserve the best optical quality of your lens? I do not really know how to maintain my filter and some tips would be useful, thanks!