If you've seen my previous blog on Eagle Falls you'll notice that most of the photos of the water have a smooth-rapid feel to them. Photographing flowing water can give you many different effects, from dramatic to subtle. It all depends on shutter speed as well as aperture setting. For those of you not familiar with the idea behind it, I thought I'd take this opportunity to give a short explanation / lesson on how to achieve the various effects of flowing water.
If you use a fast shutter speed you'll freeze the flow, giving it a rough, or violent effect. This photo was shot with a aperture setting of f/3.5 (wide open for maximum light and shallow focus) at a speed of 1/800 second, thus freezing the moment and giving it that violent look / feel.
I get a dramatic difference if I shoot at a slow speed. Here's the same spot shot with a aperture setting of f/22 (the smallest opening for this lens; maximum focus) and a shutter speed of 1/6 second. This longer exposure allowed more water to pass in front of the lens, giving it the smooth, fast feel that it has.
You can get a very subtle difference if your shutter speeds are very close together. I like to shoot a series of different speeds so I have a choice in the look and feel of the photo.
The following two photos have but a slight difference in the feel of the flow. Both were shot with the aperture set at f/22.
The shutter speed of this first shot was 1/30 second
The shutter speed of this shot was 1/10 second
The difference is slight but the "feel" and look is most definitely different. Depends on the effect you're looking for.
And one more thing that I forgot and was reminded in a comment.... You need a good, sturdy tripod.