Cameras are so good these days, the smallest flaws are evident. While there may be room for interpretation in composition or exposure, unless you're going for a deliberate blurry effect, the one constant in professional pictures is sharpness. Here are the tools and techniques to meet that professional standard for sharpness.
SHUTTER SPEEDS & TRIPODOne of the most basic sharpness techniques is using fast enough shutter speeds when handholding a camera. Did you know there's a correlation between focal length and minimum handholdable shutter speed? If you're using a 50mm lens, the slowest shutter speed you should use is 1/60 sec. As your focal length increases, so should your minimum shutter speed. In general, the bare minimum shutter speed is 1/focal length, as in 1/100 sec. with a 100mm lens, 1/500 sec. with a 500mm lens and so on. This also tells you that with a wide-angle lens you can handhold at even slower shutter speeds. When sharpness matters and you're handholding your camera, shutter speed is everything.
Speaking of handholding, the best way to get sharp pictures is to avoid handholding whenever possible. When I was a young photographer, I scoffed at tripods, discounting their ability to help me outside of long exposures that mandated stability. But after years of professional experience, I'm now convinced that even when I'm working with fast shutter speeds or strobes (which have their own motion-stopping characteristics), tripods simply help make every picture sharper. Handholding is for situations when mobility is a must. Otherwise, put your camera on a tripod and watch your pictures get sharper.
CABLE RELEASE & MIRROR LOCK-UPPutting your camera on a tripod is only part of removing your hands from the camera-shake equation. The cable release is all too often relegated to use for long exposures, but in fact, camera shake can be even more pronounced with relatively fast shutter speeds.
It's this same logic that makes mirror lock-up useful for short exposures, too. With a camera on a tripod, mirror lock-up helps to eliminate the camera shake that's caused by the moving mirror. (The word "reflex" in single-lens-reflex camera is shorthand for the reflection off the mirror that covers the sensor. It swings up and out of the way just before the shutter opens to expose the sensor. And, believe it or not, its vibrations are sometimes visible.) I've taken to employing mirror lock-up—accessed in the menu settings of most DSLRs—whenever I'm photographing a stationary subject like a tabletop product, an architectural image or a landscape. Once enabled, it requires two pushes of the cable release, the first to raise the mirror and the second to release the shutter.