Photographers are always concerned that photos turn out as sharp as possible. Photography has a seemingly endless number of challenges, but sharpness is number one. No matter how incredible your photo opportunity is, if the images are not sharp, nothing else matters. The pictures will be worthless. Too often images are almost sharp, and this is particularly vexing because if only you had paid attention to one tiny detail or two, they would be perfect.
What follows is a list of ten reasons why your images may not be as sharp as you want. Some factors are out of your control, of course, but most of the time you can address the issue that is causing the problem.
1. Image stabilization was left on when you used a tripod. The IS (Canon) or VR (Nikon) feature is designed to be used when handholding the camera. When your gear is mounted on a tripod, though, it should be turned off. There are some lenses that are said to be unaffected by this issue, and they produce sharp pictures whether the stabilization feature is left on or turned off. In my experience, though, I have never had sharp pictures when the IS function is turned on and I'm using a tripod. This is also true when I'm shooting on safari and my support is a beanbag. I lost some great shots of lion cubs nestled in a gnarled tree because I assumed the beanbag would be similar to handholding the camera. I was wrong. My images were unsharp until I turned the IS off.
2. The center column of the tripod is raised too high. The stability of a tripod comes from the fact that three legs are used to provide a firm support. When you raise the center column 12 or 14 inches above the base, it doesn't have the same rigidity, and if there is any wind or if you jar the camera when pushing the shutter button, the resulting pictures will be blurred.
3. Your shutter speed was too slow and you are hand-holding the camera. This is one of the prime culprits that result in unsharp pictures. If the shutter speed is slower than 1/60th of a second, chances are that your images will not be tack sharp. This guideline is useful for lenses in the 50mm range and wider. For telephoto lenses, the general rule is that the shutter speed should be the reciprocal of the focal length of the lens. In other words, if the telephoto is a 300mm, then the shutter speed should be 1/300th of a second or faster. If the lens is a 500mm plus a 1.4x teleconverter equaling 700mm of focal length, the shutter speed should be at least 1/700th of a second to insure sharp pictures. This is what I used to photograph the blue grosbeak, below, at my feeder.
When you are shooting in a low-light situation, the strategy you should use is to raise the ISO until the shutter speed becomes fast enough to give you tack sharp images. This is assuming you are already using a large lens aperture. If not, then open the lens up all the way before you start raising the ISO.
4. Don't handhold your camera when photographing at twilight or night. This will always result in unsharp pictures. If you raise the ISO so high to get a fast shutter speed, the pictures will be full of noise. Digital noise is quite pronounced in pictures taken in low light, so make sure you use a tripod, a low ISO, and then the long shutter speeds won't matter. The photo of the beautiful church at twilight, below, was taken in Tallinn, Estonia.
5. Autofocus can fail in low light environments. In order for the autofocus mechanism to function correctly, it needs contrast - the difference in light areas of the composition versus dark areas, or the difference between colors. When shooting at night or in a dim interior such as a restaurant or cathedral, for example, I recommend turning the autofocus off and focus the old fashioned way ... manually. This will guarantee that your pictures will be sharp.
6. When there are several planes of focus, the autofocus mechanism can be fooled. This results in unsharp pictures. A leopard in tall grass, for example, presents a challenging proposition for the autofocus feature. It can't know what the subject is, and most likely it will focus on one of the blades of grass and leave the animal out of focus. Therefore, the only solution is to focus manually. That takes all the guesswork out of the equation.
7. Doing macro photography without a tripod is like shooting yourself in the foot. Neither of these are good ideas. When you move in close and fill the frame with small subjects, you lose depth of field. What most photographers do is close the lens down to a small aperture to compensate for that loss. When you gain increased depth of field, though, light is lost and therefore a long shutter speed is needed to compensate. If you try handholding the camera for macro work, you will very quickly see that it is an exercise in frustration because the pictures will almost never be sharp. Therefore, a tripod is the only way to get sharp macro pictures. If you can't use a tripod for some reason, then your only other alternative is to use flash.
8. Doing macro photography in the wind guarantees blurred pictures. If you insist on doing macro photography when it's windy, even if you use a tripod you might as well buy a time-share in a facility with padded cells! It will truly drive you crazy. Even the slightest of breezes makes macro work virtually impossible. If you are shooting rock patterns or bark, for example, you won't have any problems (unless the wind is strong enough to buffet the camera). However, if you are trying to photograph flowers, leaves, grasses, butterflies, spider webs, seed pods, and other subjects that are at the wind's mercy, then I would encourage you to wait until the wind has died down.
9. If you don't use good macro photography technique, more than likely your images will be less than sharp. For example, use the mirror lockup feature to minimize vibration in the camera. Even the subtlest vibration can cause images to be less than sharp when using significant magnification. Every time you take a picture, the mirror in back of the lens flips up to allow the light coming through the lens to strike the digital sensor. After the exposure is complete, the mirror flips back down again. This action causes vibration, and when you lock it up out of the way, it doesn't move again until the photograph is taken. Then, after the image is made, the mirror returns to its original position.
Next, use either the self-timer built into the camera or a wireless trigger to take the picture. I use the 2-second option and it works fine. This prevents the camera from being jarred when your finger depresses the shutter button.
Finally, make sure y our tripod is tight. Nothing should be loose; all the sections should be firmly tightened, and the ball head must be fastened tightly onto the tripod itself.
10. Many lenses don't focus correctly at infinity. When you manually turn a lens (and particularly a telephoto lens) all the way to the infinity mark, it is reasonable to expect that this means the lens will be focused on subjects at great distances such as the moon, a distant mountain range, clouds, etc. This is often not true. Sometimes you have to pull the focus ring back slightly to get a sharp picture. The autofocus mechanism should accommodate this discrepancy, but if you are focusing manually it's important to be aware of this. Focus by your eye instead.
