40mm UV Filter: Found one
Chuck Fralick wrote:
Or you could just got to 2filter.com website (i think they are physically in Vermont) and buy a Marumi 40mm UV or circular polarizer. With shipping the UV was about 30 bucks and it's a made-in-Japan good quality filter. Fits great.
I know this is an extreme example - it's a picture of a downlighter in my bathroom - but I wanted something to demonstrate the problem of my 40mm Marumi filter. It's self explanatory if you look at the two pics, one with and one without the Marumi filter. I sent it back and got a refund. It was a multicoated version.
I did try the JJC adaptor and 52mm and that was fine.