Quote Originally Posted by Krzys View Post
If you find a filter just larger than a bottle cap and find a way to use it in digital photography then go ahead....
Funny you mention that.

I have a filter only just larger than a bottle cap and I use it all the time.
In fact it's the only UV filter that I use regularly, as I hate the stuff, and it's only 37mm.

prior to that, I used to use a 30.5mm UV filter too.. but that's now long gone!