You Don't Have to Go With the Flow!
By Tamia Nelson
July 7, 2009
Water moves us, and moving water moves us even more. Paddlers are always on the lookout for trophy shots, photos that capture the challenging chaos of a rapids or evoke the placid processional of a broad river. But it's hard to express a sense of motion in a still photograph. The nub of the problem is easy to see: Still photos freeze the action. That's great if you're a sports photographer, but if you're shooting moving water you'll often need something more. The pros do it all the time. What's their secret? How do they trap the essence of a fluid, ever-changing medium in a single, static frame? Well, it's easier than you might think. You just need to learn a few tricks of the trade. And the most important "trick" of all is…
Getting to Know Your Camera
Digital cameras have brought point-and-shoot photography to a new level. But they have their limitations. Of course, the "Auto" setting is great for most establishing shots. What's an "establishing shot"? Good question. It's a tag that doesn't often crop up in discussions of still photography. I don't know why. It's certainly useful. In any case, it's part of the working vocabulary of film production, and it refers to the Where-Who-When shot that introduces a scene—the shot that establishes the location (Where?), the identities of the participants (Who?), and the time of day or year (When?). A lot of the photos you'll see in most trip albums are just this sort of thing. They show where you went and who came along, in addition to fixing the action at the proper point in the cycle of the seasons. Automatic digital cameras make this part of the photographer's job easy. But Auto mode will only take you so far. If you want to go further—if you want to take your photography beyond Where-Who-When—you'll need to learn how to control your camera's shutter speed, aperture, and sensitivity (aka ISO or ASA). Warning! Not all digital cameras have a "Manual" mode that allows this. Check your owner's guide to be sure that yours does.
Ready? Does your camera check out? Then let's delve into the details:
Shutter speed determines how long your camera's sensor is open to the light. A fast shutter speed (also called a "short" shutter speed) limits exposure time and freezes action; a slow (or long) shutter speed does the opposite, turning action scenes into a blur of movement—"motion blur," in trade jargon. The resulting shot will be short on detail but long on atmosphere. And just how slow is slow? It depends. You'll have to experiment. (This is where digital cameras shine. You don't have to wait for your slides to come back from the processor to know whether or not you got the shot you wanted.) To avoid problems with the shakes, it's best to keep shutter speeds under a second. In fact, you can often get good results with speeds as "fast" as 1/30th of a second. But things aren't quite as simple as that. Shutter speed is only one part of the picture. You don't want to overwhelm your camera's sensor with too much light. So if you slow down your shutter speed, thereby increasing exposure time, you also have to close down the aperture, effectively reducing the size of your camera's window on the world. Aperture is indicated by ƒ-number, and it's a bit counterintuitive. An aperture with a high ƒ-number (such as ƒ/22, say) lets in less light, while an aperture with a smaller number (e.g., ƒ/5.6) lets in more. The upshot? A slower shutter speed demands a higher ƒ-number. Your camera's manual should tell you how to perform this balancing act to best advantage.
Sensitivity is the last variable you'll need to concern yourself with. Film is assigned an ISO (or ASA) number. The higher the number, the more light-sensitive the film. So for film photographers, controlling sensitivity boils down to choosing the right film for the subject. (Sadly, the choices get fewer with every passing year.) Digital cameras make the job easier. You can leave the sensitivity on "Auto" and let the camera determine the setting, or—if your camera allows it—you can control sensitivity manually. All things being equal, higher sensitivity permits shorter exposure times and smaller apertures. This is good news if you're shooting in low light conditions, or hoping to freeze fast action. But there's a price to be paid. The higher your sensitivity setting, the "noisier" the resulting images. In other words, shots taken at high ISO numbers may look grainy, with a noticeable loss of fine detail. If you're planning to make prints from your photos, you'll probably want to get the sharpest images possible, and this means shooting at a low sensitivity setting. The photos I shot for this article were all taken with sensitivities in the range between ISO 100 and ISO 200. That's as low as my camera will go.
Let's summarize: Low light sensitivity (low ISO) makes for sharp photos, with a minimum of extraneous noise. This is a very good thing under almost all circumstances. But to evoke motion, you often want to blur the onrush of moving water. That requires a slow shutter speed, somewhere between one second and 1/30th of a second. And that means you'll need to stop your aperture down to a relatively high ƒ-number. (Higher ƒ-number equals smaller aperture, remember?) On my Pentax digital SLR, I usually choose the full "Manual" mode, rather than the "Shutter Priority" mode. Manual mode allows me to set both the shutter speed and the aperture independently, while Shutter Priority only lets me set the shutter speed, leaving the choice of aperture up to the camera. It's not for me, thanks. If I'm going to make mistakes, I'd just as soon make them myself.
Once you've mastered your camera's controls, the next step is to figure out how you'll…
Steady the Shot
In order for your shots to evoke water's movement, you'll probably need to blur the water—and only the water. You'll want the surroundings to appear in sharp contrast. Since you're shooting at a slow shutter speed, that requires a steady hand. If your camera incorporates some sort of anti-shake mechanism (or software), this will help. Still, it's often not enough by itself. Photographers can learn something from marksmen here. A good brace will go a long way to steady a shot, as will holding your breath while you depress the shutter. But for the most consistent results, you'll need to use a tripod, taking care to set it up so that it's not buffeted by gusts of wind or vulnerable to a clumsy misstep. Since I've been known to trip over my own feet from time to time, particularly when I'm engrossed in framing a shot, I like to keep a grip on my camera even when it's on a tripod, though to avoid transmitting vibration to the camera body that usually means holding onto the neck strap. It's inconvenient at times, but I don't mind. I don't relish the sound of lenses smashing on rock or the splish-splosh of a camera hitting the water.
OK. With those preliminaries behind us, we're ready to head out and discover just what it is that makes…
A Blur-fect Picture
Slow shutter speeds are imperative, but this increases the risk that you'll overexpose the shot, even if you stop the aperture down as far as it will go. Here's an example:
I set up my tripod in the shelter of the woods just as the midday sun illuminated the falls. I chose a shutter speed of 1/6th of a second and metered for the riverside rocks, which gave me an aperture of ƒ/22. This certainly blurred the falling water, but it also overexposed the aerated pool below the falls. So I tried again, metering for the water, instead. And the result?
Better. But still not quite what I was looking for. My shutter speed here was a comparatively fast 1/180th of a second; the aperture, a wide ƒ/6.7. The shot accurately reproduces The River's characteristic root-beer-brown color, but the shoreline is thrown into deep shadow, and I didn't get the flowing-water effect I was hoping for. The high noonday sun is to blame. If the sky had been overcast, or if the sun had been lower, metering on the water would probably have given me what I wanted. A polarizing filter helps reduce glare and can sometimes rescue shots like this—but not always. I used a polarizer for both of the shots above. You can judge the results for yourself.
What can we conclude from this? Well, for one thing, if you want to slow down moving water, it's usually best to shoot in dim light. Notice that I hedged my bets with the weasel-word "usually." Rules are made to be broken, and this photo shows that some overexposed images still have the power to arrest the eye:
I shot this about 30 minutes before the previous pair of photos. The tip of the lone fern is strikingly highlighted against the dark rock, and the 1/10th-second exposure certainly showcases the moving water. The aperture was ƒ/22, metered for the rock outcrop just visible in the foreground. This photo is only one of a series of shots I made of the same scene. I rang the changes, choosing different combinations of shutter speed and aperture—"bracketing by stops," in shutterspeak—to improve my chances of finding just the right pairing. It's a useful tool. Each combination of speed and aperture yields an "exposure value," or EV. You can vary shutter speed and aperture in tandem, of course, in order to maintain a constant EV, but you can also bracket, stepping EV up and down in increments of 0.5. I did this, going as high (and low) as ±3.0 EV. And it worked.
Now let's look at the power of diffuse lighting to improve a picture. Moving away from The River and back into the woods on the same day, I stumbled on a tiny rill, overhung with ferns and wildflowers:
Indirect light filtered down through the canopy of pines, leaving most of the rill in shade. I selected a shutter speed of 1/8th of a second and matched it with an ƒ/4.5 aperture, metering on the thread of water. The sunlit portion of the stream is a bit overexposed, but I like the overall effect, and I think the shot owes its success in part to my remembering to…
Mix and Match Elements
Light-dark. Movement-stasis. Monochrome-color. Contrast is often king in photography, and shots that display moving water against a backdrop of bedrock or forest are likely to be winners—though if it's contrast you're looking for, you'll have to make sure the wind isn't tossing the trees around when you press the shutter! Sometimes you get really lucky, as I was when I happened on a rainbow in the mist over one of the staircase falls on The River:
Rock and wood frame a shot in which spectral colors contrast with the blue-white blur of rushing water. A happy combination of shutter speed (1/8th of a second—as slow as I could go without overexposing) and aperture (ƒ/32) did the biz. Of course, rainbows aren't everyday occurrences, but you can make your own luck, too. Here's a photo of a large pine, scoured to bare wood by the water's tireless hands. I captured the shot using my telephoto lens at full extension.
This has all the elements: an overcast sky, a brooding bedrock backdrop, and the poetry of onrushing water, with the naked pine testifying to The River's implacable power. I chose a shutter speed of 1/4 of a second and an ƒ/22 aperture, and I think I got it right.
It's time to slow down. Long exposures work on placid waters, too. Here's an example:
The scene? A shaded pool at The River's edge, in a place where its hectic pace slows to a solemn processional. The still water reflects the green of the forest, while the outlet ripples across the foreground. Once again, I found a harmonious blending of subtly lit, contrasting visual elements, and then made the most of my find with a fortunate pairing of exposure and aperture.
There's no reason why you can't do it, too. All it takes is a camera that gives you some choices besides full Auto. Experiment until you're happy with the result. And if you want to see more ways in which photography can evoke motion in a still image, take a look at these other photos in my Zenfolio Gallery. Then go and shoot your own.
Long-exposure photos of moving water can achieve the seemingly impossible—they can capture the essence of a fluid medium in a single, static frame. It's not quite as easy as simply pointing and shooting, but it's not very hard either. In fact, it's one professional secret that we all can share. And that's a very good thing, because paddling photographers don't always want to go with the flow. As least I know I don't. What about you?
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