by Kerry Drager
Water in motion is ever-changing and ever-magical. That's especially true when it comes to slowing down the shutter speed and capturing a beautiful sense of soft movement as you see in boulder waterfalls and slides.
This fluid-motion technique can be applied to all types of waterfalls, streams, ocean surf, fountains, and even lawn sprinklers. How slow is "slow"? To blur flowing or falling water, start with a shutter speed of around 1/8th second, and then work your way down from there - into the 1/4- to 1/2-second range. The ultimate in silky smoothness, though, generally doesn't start to set in until about a full second or so. Longer exposure times increase the slow-motion effect.
But this "Going with the Flow" technique comes with a "rule": Photographing running water is not a precise science - so it always pays to experiment.
Water's speed
Slower-flowing water requires longer exposures to obtain the fluid-movement look, while fast or cascading water can be blurred with not-quite-so-slow shutter speeds.
Distance between camera and water: The more you magnify your subject in motion (i.e., by physically moving in closer or by zooming in tighter), the easier it is to blur it. More distant scenes require much slower speeds to convey that soft-movement look.
In any case, long exposures don't just happen. Most, or all, of the following must be in place in order to slow down your shutter speed:
Low Light
This means thick overcast, deep shade, sunrise, sunset, or twilight, or indoors. Side benefit: soft-and-even light ... i.e., none of the washed-out highlights and/or inky-black shadows that can occur in bright sunlight.
Low ISO
When it comes to slow exposures, the lower the ISO the better - say, 100. Side benefit: top image quality - i.e., less grain/noise than when shooting with high ISOs.
Small Aperture
Your lens's SMALLEST opening (HIGHEST f/stop number) will automatically result in the slowest possible shutter speed for the given ISO and lighting conditions. Side benefit: a wider depth of field (what's in sharp focus from front to back in an image). How to do it: In Aperture Priority, choose a high f/stop number. The camera's auto-metering system will then compensate for the small aperture by lengthening the exposure time.
Deep-Tinted Filter
A neutral density (ND) filter cuts the amount of light entering the lens, thus allowing for longer exposures. But a polarizing filter also blocks some of the light entering the lens - by almost 2 stops. Polarizer side benefit: controlling the glare and shine on the water - as well as reducing reflections on adjacent wet surfaces to boost color saturation.
Tripod, Etc.
Long exposures require a steady camera - via a tripod or other sturdy support. To guard against vibrations: Use a cable release - and for extra protection: a self-timer or mirror-lock mode (not all SLRs have this latter feature, however).
Super-Slow Not Always Best
Although you'll seldom go wrong by shooting with the slowest shutter speed you can get, sometimes the longest exposure is not the best option. For instance, with free-flowing water (no rocks or other obstructions) or higher lighting contrast in the scene, the result can be an unsightly big-and-bright-white blur (washed out with no texture).
Lastly ...
Whenever you can, "play" with your settings, since the constantly changing water makes it difficult to tell exactly what you'll get. In other words, shoot the same scene at a few different speeds ... since there's nothing quite like comparison!
More photos:
At least three BetterPhoto galleries include many excellent examples of flowing-water effects. For inspiration, check out the following galleries:
To learn more about photography, explore the photography classes offered here at BetterPhoto.