I recently purchased a 77mm Hoya CPL Filter for my EFS 10-22mm lens.

I have been unable to get the filter clean after my first few shoots with it.

I have tried gently wiping with lens paper with a light spray of lens cleaning solution on it, then wiping with a micro fiber cloth, but it seems to have some sort of film on it and doesnt get clean enough.

I have resisted the urge to just keep polishing it with the cloth and thought Id pose the question here.

I purchased the filter off fleabay and it states that its genuine, looks genuine and is identical to my other CPL I have.

Any hints?

Cheers

Stew