A Circular Polarising filter is one piece of essential kit

[crazzy88ss]

ya, what he said.

:(

[SirEvan]

As for using it on your other lenses, just get a set of step down rings so you can use the big old 77mm on the smaller lens threads.

I always find using the polarizer underexposes outdoor shots, so I have to compensate.

a circular polarizer will affect your exposure by between .5 and 1 to 1.5 EV, depending on the strength you have it on, so you should set the EV compensation to + 1 to comp for it.

A little birdie *coughMoonMancough* told me that's a bad idea as it causes some distortion in the images.

I wanted to do that with a 77mm circular polarizer on a 72mm lens.

the only time you'd have to really worry about problems would be at WIDE angle settings, anything past the furthest wide angle setting on your lens you wont notice. You start to have major problems however if you try using step UP rings, to make a smaller filter fit on a bigger lens, because you will get the filter in part of your shot. but 77-72mm shouldn't be a problem for you.