I'd like to get some ND filters to enhance my seascapes. I am looking at graduated ND 2,4 and 8 maybe Cokin, for my Tokina 11-16 which accepts 77mm filters. When I look on eBay, there seems to be all sorts of different types, Z, P, A, and many types of holders. I have no idea what I actually need to look for. Could someone possibly shed some light (pardon the pun), on what I should buy and if there is a reputable (read cheap) supplier, point me in the direction.
Many thanks for any input.