When you're shooting macro, sharpness is especially critical. The power and impact of a shot at extreme magnification deteriorates significantly when it's soft or exhibits motion blur. Motion blur can be defeated by choosing an appropriate shutter speed, and you can ensure sharpness by using a small aperture to gain depth of field. But what happens when you want a shallow depth of field? For those images, your technique needs to be spot on. Here are a few quick tips to help you get perfect macro shots every time.
Having a rock-steady tripod is a great way to prevent any kind of camera shake, obviously. Anchoring your camera on a solid tripod also gives you the freedom to concentrate on critical focus in the frame. Your camera's AF system might try to zero in on the wrong portion of the frame. When your system is anchored, you can go to manual focus to ensure that you get the right elements tack-sharp. This works great as long as nothing moves.
Nature is often in motion, however. Whether it's an ambulatory critter or a gentle breeze, macrophotography can be frustrating as you struggle to maintain sharpness while things bounce around in your viewfinder. A technique that many pros use successfully consists of focusing manually to get close, then moving the camera slightly as things move. This is much less frustrating than trying to rotate the focusing ring or trying to let the AF system do it. As good as AF is, a flower that's shaking in a blowing wind can wreak havoc, and it's enormously frustrating to get close and then have the lens hunt through its entire focal range trying to reacquire the subject.
The tricky part of the technique is working with the tripod. Here's the rub: Trying to shoot macro handheld is fraught with potential peril. The minimum handholding speed is usually accepted as being 1/your focal length. With macro, it's a good idea to double that. For example, using a 90mm lens, the minimum handholding speed should be 1⁄90 sec. For macro, however, it's a good idea to make it at least 1⁄180 sec. to be sure you don't have any camera shake. Even if you shoot with a fast shutter speed, many macro subjects are tricky to keep framed as you're handholding. So a tripod is still a good idea even if it makes zone focusing a little challenging.
The way to do it on a tripod is to set up with the tripod legs set narrower than you'd place them ordinarily. This has the effect of making the tripod less stable, which, in this case, is exactly what we want. Some pros actually keep the legs together, almost making a monopod out of their tripod. Also, keep your ballhead just a little loose as you shoot. Because you're reducing the stability of your tripod and ballhead, it's important to choose a shutter speed that's close to the minimum handholding speed. Set your lens to manual focus and get as close as you can to a sharp image. Chances are good that things are bouncing around a little in the viewfinder, so take your time and take a deep breath and relax. By rocking your system gently back and forth, you can get in sync with the wind and get sharp photos. This technique isn't perfect, so help yourself out by shooting a lot of photos. The law of averages works in your favor when you do so.