In reply to Adam Long:
> Right, agreed, so when you stated that 'only reflected light is attenuated', like it was a big limitation, what exactly did you mean? What are you photographing that isn't reflected light?
Yes, but not all reflected light is the same is it, or polarisers would have the same attenuation effect regardless of orientation.
> And even if you photographed the sun with a long lens, (direct light yes, not reflected?) would a polariser not 'attentuate' the light? Yes it would, and crossed polarisers would attenuate it almost completely.
Agreed.