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.