Quote Originally Posted by pollux View Post
If you mounted a polariser onto a fuji g617 on top of the centre filter, would you need to stop down another stop, for example @ f11 losing one or two stops, to f16 or even f22?
1 - 1.5 stops for the CF; 2-2.5 for the Polariser. Total = 4 - 4.5 stops. 100 asa ends up somewhere around 5 asa.

So you'll also need to get your head around reciprocity failure as well. I shoot Velvia/Provia in colour and Acros in B&W to minimise reciprocity failure. Shot some film today with a Pol and CF in rainforest. Exposures were around 2-4 minutes...