Originally Posted by neuroanatomist
Hoya 82mm Pro1 Digital ND16 from buyphotogear.com(a small site I found through eBay, limited selection but low prices, and in the USA). Same brand for the Cir-PL and a clear protector.
I've been very happy with these filters. I've found them easy to clean, I like that the filters have a slim frame, and seem to be of the same quality as any B+W filter I've seen.
Originally Posted by Trowski
I should have been more specific, I meant for 4x6 mounts and filters.