ND Filters

Thanks all for the answers and advice.  I'm excited that I'm going to get to spend part of one day next month in NYC, and I'm making a wish list for B&H!  (I've ordered from them before, but I've never actually been to the store in person!)  A CP and/or ND filter maybe a "moose" filter -- thanks for the tip -- will be on my list .

And thanks too for the technique tip, Sailor Blue.  I'll give that a try.

I have 77mm and 82mm lenses, but I don't want to buy multiple filters if I can avoid it.  If I want to step up or step down, does it make more sense to buy 82mm and step down?  It seems like the other way there's a chance for vignetting.  (Though, I know polarizers may not work as well on an UWA lens.)