Tuesday, December 10, 2013
Sharpness The Deadly Dozen
Defeat these threats to sharp photos and create images that get optimum sharpness from any camera and lens
Pro lenses are designed to be durable and to hold up under tough conditions. They're also designed for optimum sharpness. But you can't get that sharpness if you don't limit the number-one cause of softness in photography: camera shake during exposure. A pro I know once told me about a workshop participant who complained that his Leica lenses weren't sharp, yet he refused to use a tripod. A lens is only as good as the photographer's technique.
6 Image Stabilization.
There's no question that image stabilization has been nothing short of revolutionary for photographers. I love it and use it often. However, image stabilization is limited. It can only compensate for shutter speeds that are a few stops slower than your minimum handholding speed. It doesn't guarantee sharpness, and it won't help if shutter speeds are too slow. Combine this with overestimating your steadiness, and you quickly run into trouble, getting less sharpness than your lens is capable of. Be sure to check your exposure, and be sure your shutter speed isn't too slow.
7 Poorly Made Accessories.
A cheap tripod or filter can destroy the sharpness of even the best lens. Why spend thousands on a camera, but hesitate to spend hundreds for a good tripod that will do more for your photography? A good tripod is an investment in sharpness that can't be matched by simply buying a new camera or lens. Plus, it will have a much longer life than most cameras of today. In addition, a cheap filter can make a really good lens look awful because the lens can't deal with the imperfections of the filter. Get a good tripod, and if you use filters, avoid the cheap stuff that has no name you recognize.
Yes, indeed, autofocus is terrific. It's hard to imagine life without it! But it can also lull you into thinking you have a sharp photo when you don't. The problem occurs when the camera places focus on the wrong area in the photo. The camera doesn't know what spot should be sharp; it only finds what seems to be important for sharpness. With wide angles and when you're at a distance, this isn't a problem. Up close or using a telephoto, and it's definitely a problem. Up close, depth of field is very narrow, and missing the right focus point by even a fraction of an inch can make a photo look out of focus. When photographing wildlife, even insects, the eyes must be sharp or the entire photo will seem soft to the viewer. Lock your autofocus with the shutter release or AF-lock button, or use manual focus. If you need to, use a magnified view in Live View to get accurate focus.
9 Mishandling Wide-To-Telephoto Zooms.
I'm not talking about lens quality here. There are some marvelous wide-to-telephoto lenses available today that are sharp and offer excellent image quality—if you handle them right, and that's the challenge. Remember the Minimum Handholding Rule of 1/focal length = minimum shutter speed. That rule indicates that wide-angle lenses (shorter focal lengths) can tolerate slower shutter speeds than telephotos while maintaining sharpness.
Often, I hear misleading information on the Internet about how a lens isn't as sharp at the telephoto setting as at the wide-angle setting when, in fact, that's more about the photographer's shooting technique than it is about the lens. These wide-to-tele zooms create two challenges for sharpness at the telephoto end: First, because a faster shutter speed is needed, you need to pay attention as you zoom in; second, these lenses usually stick out from the camera quite a bit as they zoom to telephoto, and this can make them unstable both for handholding and when on a tripod. Be aware of this and use an appropriate shutter speed.
If your lens has a tripod mount or tripod collar, use it! The camera and lens are much more stable when attached by the lens collar and it reduces stress on the lens mount.
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