Any advice on getting a graduated ND filter? I started looking through them on Adorama.com and was surprised by the selection. Particularly the "light grey ND" and "dark grey ND". I would assume the light grey doesn't block as much light as the dark grey but not sure how much would "enough" for a typical landscape / sunset shot. Also since a sunset shot would most likely include the sun in frame would the coating of the filter be more important than a filter that's typically not used with the sun in frame (in terms of preventing flare)? Any advice or specifics that I should consider?