I bought the Fuji adaptor/hood and originally used a Hoya digital clear with it. I ALWAYS wound up finger-printing it putting it on or removing it. And that $&*$@!!!! Hoya is the hardest filter to clean I've ever seen.
So I got the Marumi 40mm: Cleaned it once. Seals off the front element. No fingerprints. No dust behind it like the 52's. Hood screws right into it. No vignetting. MUCH better. I'll get the polarizer as well. Lens cap goes right on over it.
If I had some 46's, though, that's a great idea.
All the Best,