Quote Originally Posted by TheFlyingCamera View Post
I saw this filter and I was wondering if anyone here had ever used one and how well they work...

I was given a no-name 77mm version of same, and have experimented with it a little bit. It isn't fully "calibrated" yet, so I don't have any good examples to show.

They are available at a number of different price points, from incredibly cheap to really expensive.

The cheap ones are vulnerable to being uneven in their effect.