For anyone who's interested: About the Singh-Ray Gold & Blue polariser, I just emailed them asking about whether they had 82mm filter sizes and the answer was that they haven't managed satisfactory results with it at that size.. So I suppose that'd eliminate quite a few of the Sigma wide options, like the 20 1.8 or the current 19-35 2.8-4 (though they're going to have a 77mm one come Jan). Not a big blow to the Pentax options though..
Cheers, Ryan
