|Thanks Steve and David!
I had never done this before either, but I got the idea from one of the non-DPC members (Ben) of the Ithaca GTG. He brought some of his images in a portfolio and he had one image of swirling leaves that blew me away. This was during lunch, and afterwards, I was determined to capture the swirls. I actually got some others that were very nice--here's one I was considering for the free study (but I went for the Streamlines photo instead, which did pretty well):
In this case, the exposure was only 6 seconds. I didn't have an ND filter, only my GNDs, and other people were using their NDs. I believe I used two of my GND "in opposite directions" (how's that for improvising) in this capture.
By the way, while we are on the subject of fantastic captures by jtlee321, I had his 2nd place ribbon winner in Landscape in Portrait as my top pick! What a fantastic shot, and composed in the style of my favorite landscape photographer, David Muench.