Filter help

Hey everyone, I was reading the sticky about the filters and I was just thrown off, it didn't really make sense to me. I'm going to be purchasing a Sigma 10-20mm next week and I've read a couple of threads about people recomending filters and not only that I've had a couple of people recomend CP (Cicular Polarizers I'm assuming) to help get rid of unwanted reflections on cars (what I photograph most), but right now I'm just confused lol. The sticky said stick to Hoya's, Kenko's, or B+W, and Heliopan, but what diameter size do I need for the Sigma 10-20mm and what filter should I be looking for?

I was also wondering if I need a filter for my 70-200mm F/4 L, I've read posts about people just recommending UV filters to protect the front element of the lens, would I need a CP for the 70-200mm or would it render no help?

Thanks for the help everyone! =]

Caster wrote in post #3080663
what diameter size do I need for the Sigma 10-20mm and what filter should I be looking for? I was also wondering if I need a filter for my 70-200mm F/4 L, I've read posts about people just recommending UV filters to protect the front element of the lens, would I need a CP for the 70-200mm or would it render no help?

The 10-20EX takes a 77mm front filter. See the Sigma on the left and Canon on the right (both take 77mm filters):

HTTP response: NOT FOUND | MIME changed to 'image/gif'

A cpl will act just the same, whether it's on your 10-20, or 70-200. If you find that you don't use the 70-200 much in situations where it would benefit from a cpl you could just get a set of step-down rings to use the 77mm one from your Sigma.

Thanks for the quick info, it sounds like you guys don't think I should go with the CP, but I'll keep looking into it. If I do I'll probably go with a 77mm and a step-down ring so I can use it for my 70-200mm =]

If you want the CP for reflections on cars, by all means go for it. The uneven effect on the sky is most noticeable when you've got a wide expanse of sky in the picture; if you're working on a close-up subject that won't really be the case. I have individual CPLs for all my lenses; I don't want to have to change filters when I'm changing lenses.

Thanks for the feedback everyone, now before I order my Sigma 10-20mm and CPL filter, what filter would be a good choice? Everyone's recommending Cokin, Hoya, B+W, but I don't know of any specific filters.
Assuming I'm going with Hoya (if theres anything else better please let me know) I found 2 77mm CPL filters:
Hoya 77mm CPL: $76.50
and
Hoya 77mm CPL HMC: $155.95

Is there a reason the CPL is double the price? Is it only the mutlicoating? I've read several threads that I should go with a multicoated filter, is it that big of difference? (Practically double the price) - I might have to rethink going with a filter as I'm sort of tight on the budget..