So many nice waterfall pics that have shown here of late - they all make me wish I would finally get my ONE good photo of rushing water ... but water here simply cannot fall! It's flat as a plate where I live (mostly). I still have to ONCE get my exposure on wter so right as here to have it white and rushing and half foggy, and not have camera shake. Did you have to apply an ND filter (+so-and-so-much?) to get a long enough shutter speed?