Here's what might sound like a really dumb question for some of you. How exactly are people spot metering and calculating exposure when using a polarizer? Should you meter from the area that is highly polarized or not highly polarized? I guess this is the difficulty - the 1-2 stops of polarization filter factor doesn't effect all portions of the scene, and one has to be mindful where the highlights lie.

I feel like I am always guessing to some degree when I use one with the LF or my MF SLRs. I'm largely using colour transparency film for my nature work, so accuracy is necessary. It seems when I do get it slightly wrong, its usually to the err of underexposure.