different filters for differnet effects and purposes. the most commonly used one is the UV filter, you can see the site spree posted for more info. a UV filter should cost about $20 thereabouts i think. hope this helps, cheers!
Here's the pricelist from this forum and normally we don't stack polarizers over UV filters, in fact, we don't stack anything over UV filters, will cause lots of problems.
different filters for differnet effects and purposes. the most commonly used one is the UV filter, you can see the site spree posted for more info. a UV filter should cost about $20 thereabouts i think. hope this helps, cheers!
Price of a filter depends on its size, brand and grade, so the price of a UV filter is not fixed. The price of a UV filter from a good brand like B+W can cost more than the price of a polarizer from a cheap brand like Tokina, so it all depends.
And then you will get lots of problems. I can imagine the next questions here: "Help! My filter got stuck!" or maybe "Help! there is this black thing in the corners of my picture!"
It doesn't hurt to spend more time reading. Keep in mind: whatever lens you have it was designed to work perfectly fine without any filter. Your filter cannot improve anything, but cheap ones will give you various new problems.
Finally: filters go according lens diameter, not focal length.
Something to consider about filters: http://www.luminous-landscape.com/columns/sm-feb-05.shtml
Some lens have a deep front barrel (lenses like tamron 90mm f2.8) so the front element is more or less protected, which means that you might not need a filter.