Image degradation with UV filters
Interesting. I have no answer or even an idea as to why.
I do use Hoya PRO 1 Digital UV and Protect filters and one Kenko Digital filter. I also have Hoya CPL (regular) filters for all my lens.
I have used a filter and it did harm IQ I was just starting and did not know how bad a bad filter could be. The filter was not even coated, but I did not know it should be! I did have a bad CPL filter that would distort the pic under certain heat/humidity conditions. I have since purged my system of all bad filters.
I do check clean and test occasionally my filters. I even test for flair. So far using Hoya Digital filters I can not prove they help or harm any pic in any situation I have tested. My Sigma 10-20mm is one lens I keep a real close eye on the filter because of flare issues. However anytime there is flair in the picture removing the filter has not helped at all.
I agree people should check now and then that the filter is not doing something they don't want.