Digital and Mechanical Shutters Continued

regarding video recording, to learn more about this phenomenon.) When you press the shutter button, the light is stopped in one of two ways, or a combination of the two:

■ A mechanical shutter (like the ones in film cameras) closes, to stop the light, then opens briefly to take the picture at the selected speed, and then closes again. (All professional or prosumer and most consumer digital cameras have mechanical shutters.)

■ Using digital programming, the image sensor's sensitivity to light is closed down, activated to take the picture for a predetermined fraction of a second, and then closed down. Such digital shutters are sometimes used in conjunction with a mechanical shutter. Only the least expensive digital cameras rely solely on a digital shutter.


A slow shutter speed will blur motion. That includes any camera motion or movement. In other words, if you use a slow shutter speed, even the slightest movement or shake of your hand can blur your photo. Think your hands are rock steady? Think again. Just the natural act of breathing will cause your hand to move or shake enough. If your shutter speed is fast enough, the natural shaking of your hand won't significantly affect your picture. But at slower speeds, the slightest movement can cause your photo to look less than sharp and out of focus.

Here are some guidelines for handling your camera at slower shutter speeds:

■ For the average person, any shutter speed slower than 1/60 of a second should be shot on a tripod. Some very experienced, rock steady photographers can get away with hand holding at 1/30 of a second, but for most of us, it is generally inadvisable.

If you don't have a tripod handy, brace your camera on a table, gate, tree, wall, or other solid immovable surface. If you have nothing else available, brace it by locking your elbows against your chest and pressing the camera against your forehead.

■ S-q-u-e-e-z-e, rather than press the shutter button. A light touch is far less likely to jolt the camera than a vigorous click. Most cameras have a two-step shutter (pressing halfway freezes exposure and focus settings), and the best way to take a shot is to depress the shutter halfway just before you are ready to shoot, and then lightly depress it the rest of the way to take a picture.

■ To eliminate even the tiny bit of shaking that you can cause by squeezing the shutter button, use the self-timer on your camera. (See Figure 6-6.) Most cameras have a 10-second delay (good if you want to be part of the picture), but a number also feature a more useful 2-second delay.

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