how to use a spot filter?

[s00pcan]

Ok so I went to a camera shop to buy a uv filter and a polarizer.. then they say "buy two get one free!" agh! That means I had to choose one of the special effect filters that I really didn't need. (my g3 already has an nd and a good macro trick) So I somehow picked a spot filter because I really didn't care. It's basically a closeup lens with a hole in the middle. So how do I use it? (what zoom, dof?) And how do I reduce the ring from the hole in the thick glass?

[G3]

A spot filter is not really a close-up filter. It doesn't have a magnification factor of it's own. It is used to give a soft-focus effect to the perifery of the photo while the center spot is in sharp focus. It is used for portaiture. You just use normal metering for the exposure.