Sharpness The Deadly Dozen

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Chaparral yucca in the Santa Monica Mountains in Southern California show sharply against the morning sky.

Want Sharp Photos?
Just buy a better lens, right? If it were only that easy. Many photographers have tried this solution with unsatisfactory results. The pros get consistently sharp images. How do they do that, even when they're not using so-called pro lenses? One thing they do is pay attention to the 12 challenges in this article and work hard to minimize their damage. I guarantee that if you pay attention to them, too, you'll gain consistently sharper photos and you'll get the best from whatever gear you own.

[Pro Tip]
When you have to shoot a slow shutter speed handheld, try setting your camera to continuous shooting. Press the shutter and take five to six photos in a burst. Because the camera isn't moving much between shots, you'll often get at least one sharp shot in the group, if the shutter speed isn't impossibly slow.

1 The Minimum Handholding Speed Rule: 1/Focal Length = Minimum Shutter Speed.
The classic rule of thumb for sharp photos is to set a shutter speed equal to 1/focal length as your minimum shutter speed for handheld sharpness. That held true for 35mm film, and likewise, it applies to full-frame image sensors. With smaller sensors, you need a faster shutter speed. Use the magnification factor for the sensor format and plug in a new focal length: 1.5X for APS-C and 2.0X for Micro Four Thirds (MFT). Here's how that would work for a 100mm lens:

These two shots of Balanced Rock in Arches National Park, Utah, look very similar in sharpness at a small size. Enlarged details show the true story. The sharper photo has more contrast and image brilliance. Both were shot on a tripod. The sharpness problem isn't simply blur or not blur. Fig. A and Fig. B look about the same printed small, but enlarge them as seen in Fig. A-1 and Fig. B-1, and they're definitely not the same.

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Traveling light at a location in Japan, I had no tripod. Up close, camera movement is amplified. Shooting the camera continuously gave me a series of shots with at least a few of them sharp.

This web was shot at 1⁄1000 sec., perfect for a sharp photo...or not. This photo isn't sharp because it's up close and shot with a long telephoto, both of which magnify any vibration, making sharpness a challenge.

2 Overestimating Your Steadiness.
I find that a lot of photographers overestimate their ability to get sharp photos with a given shutter speed. The shutter speeds I listed in the Minimum Handholding Rule section truly are a minimum. I've found that many photographers can't get the full sharpness with a lens at even these shutter speeds. Do a test and compare your shooting handheld versus the camera on a tripod. I've done this and discovered that, with moderate focal lengths (neither wide nor tele), few people can match tripod sharpness at speeds of less than 1⁄125 sec.

3 Overestimating The Power Of A Tripod.
Use a tripod and you get sharp photos, right? Yes—most of the time, but having this expectation that using your tripod automatically yields a sharp photo can take you in the wrong direction. Tripods help, but you can get poor sharpness even on a tripod when there's vibration causing camera movement during exposure. Wind is a big problem, but also just pressing the shutter too hard, or even mirror bounce, can be a problem. You need to use a fast enough shutter speed to deal with the conditions or do something to minimize camera movement. A cable release can be helpful, but I find them a pain to use, so mostly I use the two-second self-timer to reduce camera shake when I'm shooting with the camera on a tripod. Also, Live View is great because the mirror is essentially already locked in the up position.

The camera was locked down on a very solid tripod, but the picture isn't sharp. This day dawned in the Alabama Hills near Lone Pine, Calif., with so much wind that it threatened to knock me down, too. That, combined with a telephoto lens, created so much vibration that it was impossible to get a sharp photo, even on the tripod.

4 Auto Exposure.
Now, this may seem odd since a lot of pros use auto-exposure, especially aperture-priority auto-exposure. Here's the problem: In aperture-priority, you can easily forget to check the shutter speed the camera is setting, so the camera ends up with a shutter speed that's too slow for sharpness, either handheld or on a tripod. The answer: Simply pay attention to shutter speed and use something that will give consistently sharp photos.

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This image of chaparral in the Santa Monica Mountains looks okay, until you look closer. The rocky cliffs aren't sharp. The camera has autofocused on the wrong part of the scene as seen in the detail shot.

5 Pro Lenses.
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.

8 Autofocus.
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.

This paintbrush in the Eastern Sierras should be sharp. It was shot from a solid tripod, but was taken at a telephoto focal length with a lens that had no tripod socket. The lens sticks out and unbalances the camera, creating vibration. The little white lines in the detail shot should be dots of light.

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.

[Pro Tip]
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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10 Have No Fear Of Wide Apertures.
There's no question that lenses aren't at their sharpest when shot wide open. But as lenses have improved, sharpness at maximum aperture has gotten better. Also, modern lenses become excellent stopped down as little as one stop from maximum. Yet, many photographers fear maximum apertures and consistently stop down their lenses to ƒ/16 or smaller. That results in slow shutter speeds and increased diffraction, which reduce sharpness either on or off a tripod. Wide apertures give you the option of fast shutter speeds, which minimizes camera movement during exposure, plus the contrast of a sharp subject against an out-of-focus background makes the subject look sharper.

[Pro Tip]
It's better to have a sharp photo with a little noise than a soft photo with no noise.

11 The Diffraction Challenge.
This was explained in detail in "Limiting Diffraction" in the October issue of OP (you can also find it at www.outdoorphotographer.com). Years ago, some manufacturers made few lenses that stopped down below ƒ/16 because image sharpness fell off because of diffraction. Diffraction occurs when the light goes through a very small lens opening (small ƒ-stop). The light scatters slightly, which yields softness in the image. Most lenses show a significant drop in image sharpness as you go smaller than ƒ/22 (and some show big drops even by ƒ/22). Test your lenses to see where diffraction takes hold and your photos begin to look unsharp, and don't assume that just because your lens can go to ƒ-stops like ƒ/22 or smaller that you'll get good image quality at those ƒ-stops.

Don't be afraid of shooting wide open or close to it. This aster was shot with a telephoto zoom and extension tubes with the lens stopped down one ƒ-stop from maximum.

12 Have No Fear Of High ISOs.
A low ISO was always the key to image quality back in the days of film and also in the early days of digital photography. Unfortunately, the impression that you have to use a low ISO has endured, even though newer digital cameras can handle higher ISOs beautifully. Every DSLR or digital interchangeable-lens mirrorless camera I've seen on the market today can shoot at ISO 400 and produce image quality exceeding the ISO 100 slide films of a few years ago, and these digital cameras handily beat the old high-ISO films. Do some quick tests, and you'll see that you can shoot at ISO 400 or 800 with excellent sharpness and overall image quality.

Rob Sheppard's new blog is www.mirrorlessnature.com, and his latest books are a series of e-books from Peachpit Press about black-and-white, color and lens choice in nature and landscape photography.