A filter is....

[Poisson Du Jour]

Oh, i'm sorry. I agree with the other posters about sales pitches and ploys. A UV filter is generally a UV filter, a cheap spiratone is probably just as usable as an expensive hoya hmc one.

!!

 

[Excalibur2]

I like a good polarizing filter.

Well there must be polarisers and polarisers......because I was testing a new lens out (with and without on a film camera) and the pic with the polariser was less sharp.