Hi Moose. I am trying to purchase an ND filter for use in shooting long exposure waterfalls. I bought a Hoya veritable ND filter but it isn't any good - not sharp and exposures are too short. So, I guess I have to shell out some big bucks. So, my question to you is, if you had to buy 1-2 high end ND filters, what brand and "stop" would you recommend?