Hello - Is there any reason NOT to use a circular polarizer screwed on the end of a Nikon lens instead of a 4x4 dropped into a mattebox? I know a mattebox has its advantages... just thinking of the polarizer itself. Thanks!
Its fine.
Mattebox has many advantages but its expensive and so are the filters - unless you are using grads and are worried about lens flare it has no optical value.
I've gotten along fine without one for years though if I had the dough for a good one I'd buy it tomorrow.
