In most cases when you make a landscape photograph you want everything to be clear and sharp. But there are exceptions in which allowing part of the subject to blur adds a sense of motion to the scene.
This is particularly useful when shooting moving water. If you expose flowing water at a fast shutter speed that stops the motion, the water looks unnatural. In fact, it can even look like frozen ice. By using some simple tricks you can fool the eye into “seeing” the motion of the water.
Here’s an example in Fig. 1, where a mountain stream flows around a red granite boulder. The boulder itself remains sharp while the water is converted into a swirling maelstrom of blurred images. This photo was made in Rocky Mountain National Park. The exposure was several seconds long.
To achieve the effect of blurred motion in water, follow these steps. The goal is to slow down your camera to use the longest possible exposure.
• Set the ISO on your camera to the lowest setting. This controls the sensitivity of the sensor in your camera. On most cameras you can choose an ISO of 100 or less.
• Use a polarizing filter. This will reduce your exposure by about one-half stop while also helping eliminate reflections in the water.
• If you have it, add a neutral density filter to cut the light down even more. A 0.9 ND filter will remove three stops of exposure.
• Finally, set your lens to the smallest f/stop opening to further slow down the exposure time.
Let’s put all this together. If our exposure at ISO 200 is 1/60th second at f/8, we can slow down the shutter speed by two stops by switching to ISO 50. That takes us down to 1/15 second. Then add in the effect of a polarizer and the exposure becomes 1/6 second. Stopping down the lens to f/16 adds another two stops, taking us to one-half second. Finally, a 0.9 ND filter slows it all the way down to 4 seconds, more than enough to capture smooth flowing water.
Here’s another example in Fig. 2, this one of North Clear Creek Falls near Creede, CO. Here the water foaming down the cliff and roiling around the scattered boulders seems like marshmallow foam.
There’s one more necessary factor to make this work. Because of the long exposure time, the use of a tripod is mandatory.
Fig. 3 gives one more example, this time Bridal Veil Falls near Telluride, CO. In an exposure of several seconds the stream of water falling from the old water mill is turned into a blur of implied motion.
David L. Brown lives in Moab where he guides photo tours and puts on workshops. An exhibition of his fine art prints will be on display at the MARC (Moab Arts and Recreation Center) May 14-June 9. He can be reached at 435-210-8158 or through his website at www.imagequest.photo.