Is that just another way of saying Polarising Filter or is it different?

Copied from Steve's Digicam Dictionary link. "Polarizer - A photographic filter for eliminating glare and reflections. Just like your polarized sunglasses get rid of annoying glare, the polarizer filter does the same for your digicam. However - there are 2 types, linear and circular. Linear is for film only, it screws up most auto focus systems on digicams. Therefore be sure you use a circular polarizer filter. It can also be used to darken skies.

the differences between the 2 types are in the mechanisms for polarizing light.

i started an explanation but i think this one is good enough:

http://lynnfarmerphoto.net/35MMBoard...olarizers.html

http://www.a1.nl/phomepag/markerink/pol_circ.htm

sjms, that's a couple of excellent articles! Thanks for your answers to a question I have had for quite some time...