Whether you're capturing running water, stilling seas, or abstracting patterns long exposures provide a perfect strategy for visually conveying the energy of nature
The magic of photography has always been its ability to freeze an instant in time—to capture what Henri Cartier-Bresson famously termed the decisive moment. It’s magical because we can’t see the world in that way—we have no pause button to savor our experiences stopped in time.
But a single, frozen instant doesn't express motion very well, and that’s where long exposures can add another dimension to still photography—the dimension of time. You can take what would be a static image captured at a fast shutter speed and transform it into something dynamic. An effective tool for artistic interpretation, it’s also fun and, with just a little practice, easy to do with ordinary photo gear.
The Water Ballet
For a nature photographer, no other subject presents better opportunities for capturing long exposures than moving water. Waterfalls, cascading streams, and ocean waves are but a few examples.
You’re going to need a tripod, a remote shutter release or the camera’s 2-second self-timer to avoid camera shake, and preferably overcast lighting conditions. The lower light in them makes it easier to achieve longer shutter times, and the light is more aesthetically pleasing, too.
I approach a waterfall or stream scene just as I would any other landscape. I work in aperture-priority auto mode (Av or A), choose an f-stop that gives the desired depth of field, then adjust the ISO until I get the shutter speed I want—higher ISO for faster speeds, lower one for longer exposures. I often need a smaller aperture than necessary to slow things down.
That’s because one problem encountered in long-exposure photography is too much light. If you just can’t leave the shutter open long enough without overexposing the image, opt for a neutral-density (ND) filter. These reduce the amount of light entering the lens, allowing for longer exposure times than would be possible otherwise. The key is that they reduce light uniformly, so contrast and dynamic range are not affected—unlike a split neutral-density filter.
ND filters are available in different strengths designated by either the number of stops they soak up or in terms of optical density. A 3-stop or 0.9 density ND is ideal for waterfalls in bright sunlight, slowing the exposure to a second or so. A strong 10-stop or 3.0 ND can blur clouds over several minutes, even on a bright, sunny day. Variable ND filters are also available, although these can be expensive.
How much you should slow things down is a matter of personal taste. The volume of water plays a big part in making the decision: Longer exposures work best with lighter streams and help express grace or fragility. Relatively faster shutter speeds are more effective for heavier cascades, as they help convey the feeling of power or strength. My own preference is to keep some texture and detail, and that means shutter speeds of 0.5 to 4 seconds for most situations, but there are plenty of exceptions.
For ocean waves, a very long shutter speed—20 seconds to several minutes—can smooth out the water and reduce distraction in the image. Waves, surface undulations, and refracted light all blend together into a creamy, smooth surface, leaving only the essential elements that make a powerful composition.