I just got back from Yosemite NP. The waterfalls in Yosemite are either at peak or near peak. This image is from one of the minor falls. I cranked up the ISO to 800, opened the lens to f4 and got an exposure time of 1/3200. Looking at the image give the viewer an idea how fast the water is coming down and how much power and speed there is involved.
Enjoy and keep on photographing!