Rivers and waterfalls are truly a visual treat. There is something refreshing and hypnotic about the perpetual motion of the water as it cascades over the rocks. This is a subject that is a favorite of many photographers and by following a few simple tips you too will relish these images.
By its very nature, a waterfall is a subject in constant motion and one of the best ways to illustrate this is to show that motion in your photographs by blurring the water. Motion blur in any image is controlled by the shutter speed so you want to set your camera up for a slow shutter speed. You will need a tripod to keep the camera steady so the only motion blur in your image is the water and not from camera motion.
To get a slow shutter speed, set your ISO to a low setting like ISO 100. The aperture should be stopped down as small as it will go, probably f/22. If you have a polarizing filter, use it too – it will help you slow the shutter down even more. Don’t be surprised by how long a shutter speed you get, I’ve shot rivers with shutter speeds longer than 30 seconds.
One thing you have to be concerned about is over exposing the photo. Often the white bubbly part of a waterfall can become overexposed and when that happens you loose all detail and texture in the water. If shooting in manual mode, use a spot meter to measure the light reflecting off this white portion of the water and then set your shutter speed so that the meter indicates about a +1 ½.
To verify your exposure check the histogram or the highlight indicator to see if any part of the image is overexposed. If so, just adjust the shutter speed a little faster until you eliminate the problem.
Finally, no discussion about this type of photography would be complete without a mention about personal safety. Rivers and waterfalls wield a tremendous amount of power and they should be respected. River banks can be very slippery and can also give way without warning. In the month before I visited the site in the photo above, two tourists got too close to the river and slipped to their death. Use caution and observe all warning signs.