Want to ensure your pictures are sharp every time? Then you’d better get good at keeping the camera steady and choosing the correct shutter speed based on the lens you’re using. Most of us know that a too-slow shutter speed won’t freeze a fast-moving subject—like an athlete running or speeding car—but those are pretty specialized circumstances. Shutter speed matters every time you’re holding your camera by hand, no matter whether the subject is stationary, moving fast or standing still. So when it comes to eliminating blur caused by camera shake, you’ve got a few options.
First and most obvious is the use of a tripod. With the camera locked down on a stable platform like this, camera shake is all but eliminated. Even with a slow shutter speed that’s way too slow to handhold (such as one second), a tripod will make it tack sharp—especially if used in conjunction with a cable release or remote trigger, as well as added in-camera options such as mirror lockup, which prevents even the tiniest vibrations from a DSLR’s moving mirror from causing any camera shake. The only motion blur you’ll encounter in tripod-made images will come from the subject’s movement during the exposure.
Using a tripod, however, has its drawbacks. Many situations make it impractical, if not impossible, to use a tripod. Even when the situation permits it, the tripod changes the way we work—makes us more deliberate and a bit more methodical. That can be a good thing or a bad thing. If part of your process is exploring a scene and shooting from the hip, a tripod makes this very difficult. In these situations, the next best option is to use a lens with image stabilization (vibration reduction) built in. This option is especially important with telephoto lenses and long zooms, but it’s useful in almost every situation. Image stabilization can add two to four additional stops of handholdability. Meaning that if you could normally achieve a sharp image at, say, 1/60th of a second, a two-stop benefit would allow you to safely handhold at 1/15th. Four stops of stability would safely get you down to—believe it or not—a quarter of a second. That’s an impressive amount of extra stabilization without losing the ability to handhold the camera.
But when you aren’t using a tripod or a lens with image stabilization, the best way to minimize camera shake is to match your shutter speed to the focal length of the lens. Camera shake occurs any time we take a picture while handholding a camera, but the impact changes depending on the lens. This makes sense when you consider why camera shake causes blurry pictures in the first place.
When the camera moves while the shutter is open, a stationary subject appears to be moving across the plane of the sensor. The faster that movement, the greater the opportunity for motion blur. With a wide-angle lens, subjects appear smaller and farther from the lens. This means that they move across the sensor slowly compared to a telephoto lens, which makes them appear larger and closer. In short, when a telephoto lens enlarges a subject, it also amplifies blur caused by camera shake.
To that end, it’s best to use a simple rule of thumb to ensure you’ll never use a shutter speed that’s too slow for a given lens. The slowest shutter speed used for handholding should be equivalent to the focal length of a lens: 1/focal-length.
Using a 50mm prime? You’d better handhold no slower than 1/50th of a second. With a 500mm lens, you’ve got to handhold with a shutter speed of at least 1/500th. Simple, right?
In practice, this is a great way to minimize blur caused by camera shake. But rules of thumb are just that, and you’ve got to factor in your own working style as well.
For instance, I regularly photograph portraits with a medium telephoto 85mm or 100mm lens. And while the aforementioned rule dictates that I use a shutter speed no slower than 1/100th for that, I much prefer to handhold my camera at 1/250th or even 1/320th most of the time. It’s because when I’m working fast and exploring a scene and moving my camera, it’s really easy to push the limits of a minimum shutter speed. So when at all possible, I push my shutter speed up into the triple digits (1/100th or faster) whenever I handhold my camera—even with a sub-100mm prime lens. Because I’ve found myself with slightly unsharp pictures on occasion even when I’ve followed that technical rule of thumb. To solve that problem, I up my ISO and open my aperture as needed in order to provide an even faster shutter speed to completely eliminate camera shake.