Here are a couple of long exposures of running water. I didn't have a neutral density filter with me, so I waited until the sun was setting and the light growing dim in this forgotten shadowy valley. When it was dark enough for a 30-second exposure, I took a couple of shots. Before long, it became too dark, and even with an aperture wide open, 30 seconds left my images underexposed. I was happy with my photos. Long exposures of running water display what the eye doesn't see, and have a fantastical, magical quality.