Very cool shot Jim, I love going out for waterfall shots and a friend of mine helped me purchase some of the neutral density filters that Big Dog is talking about. When you go out in mid day and try to slow down you're shutter you'll need them for sure. Give's that water flowing look instead of the dead stop like what happens with prop planes.
Here's one of my favorite waterfalls, it's Beaver Brook Falls in Upper NH.
The waterfalls look so different in the winter, I got the kids and I saw snow shoes and I use them to hit the waterfalls during the winter months.

I'll post the brand name of my 3 set filters I have, highly recommended!
I still haven't tried HDR photo's, need to take a stab at that. I've seen some amazing shots and I've seen some WAY over processed shots.
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XboxLive Tag: DOBrienTG1969
Dave O'Brien,Top Gun PhotographyNikon D200
Nikon D7100
Nikkor 70-200VR AF-s F/2.8
Sigma 50-500 & 17-50 F2.8