I have a circular (hoya I believe) polarizer for my most commonly used lens (62mm). However, I have a couple of other lenses it doesn't fit and I was wondering if the Cokin linear polarizers would be a better option than step down rings. Also, would a circular IR filter work better than the cokin rectangular ones? I'm trying to finish up my X-mas list and was wondering if I should go with the less expensive Cokin version of the IR filter or the screw on type. The cokin one must be a relatively new filter because the only ones I can find on the internet are in other countries. Anyway, any help would be appreciated. Thanks!