CoolToolGuy wrote in post #5806366
Hoya filters are notoriously tough to clean. Even if you send the filter back, some day you will get a smudge on the new one and you will likely run across the problem then. Regular lens cleaning fluid will not cut it.
There is a cleaner known as ROR - Residual Oil Remover - that works really well on Hoya filters. B&H sells it, I'm sure other places have it as well.
http://www.bhphotovideo.com …esidual_Oil_Remover_.html
Have Fun,
Hoya filters are notoriously tough to clean. Even if you send the filter back, some day you will get a smudge on the new one and you will likely run across the problem then. Regular lens cleaning fluid will not cut it.
There is a cleaner known as ROR - Residual Oil Remover - that works really well on Hoya filters. B&H sells it, I'm sure other places have it as well.
http://www.bhphotovideo.com …esidual_Oil_Remover_.html
Have Fun,
That's so true...
I've been using Formula MC for a couple of decades now, and it also works very well on even the toughest filters. I finally broke down today and picked up a bottle of ROR. 
A regular UV filter can be washed with Dawn dishwash soap (but do NOT try this with a CPL).
