Now that I have two 77mm-thread lenses and only 1 filter (UV) that is 77mm, I'm looking to purchase 4 new filters: 1 UV, 1 circ. polarizer, 1 1.2 ND, and a 4-pt cross-screen. The UV is to have on the other lens as protection and to forget about it being on there. The other three filters I don't think will be necessary to have in duplicate because I'll use them rarely enough that I'll switch them. The polarizer is for the standard reason. The ND is for shooting waterfalls, and though I would prefer an even stronger one (like this 3.0 one that's a 10-stop filter), I think a less strong ND filter may have more general purposes than a 3.0. (Any comments on that would be helpful.) And the 4-pt is for when I do some astrophotography to have as an option. All that said, there are a gagillion different brands and coatings and glass types that make these filters run the range from, e.g., $35-$200 each. My basic question is what should I be looking for in terms of glass and coatings - and even brand - when shopping for good-quality filters? Thanks!