A polarizer polarises directional light. Like the sun's. It also absorbs up to 2,5 stops of light.
If the main light is not directional (overcast day, open shadow, etc.) it will not (cannot) be polarised by the CP. But it will still be absorbed, and thus the CP will act as an ND filter would.
There is however nothing 'graduated' about it.
If the main light is not directional (overcast day, open shadow, etc.) it will not (cannot) be polarised by the CP. But it will still be absorbed, and thus the CP will act as an ND filter would.
There is however nothing 'graduated' about it.