Sometimes you’ll want to shoot in low light and use a long exposure, such as when photographing fi reworks, star trails, or streaks of light coming from cars on the street. The fi rst thing you’ll need in order to capture quality images with long shutter speeds is a sturdy tripod. It’s also a good idea to use a cable release (see Chapter 3) or the self-timer to prevent any type of movement in your image when pressing the Shutter button.
Because your camera is stabilized on a tripod, you don’t need a high ISO. In fact, it’s actually better to keep the ISO low (usually between 100 and 400) to reduce the amount of noise in an image. Often with long exposures you’ll introduce a different type of noise in your image because of the amount of time the shutter is open—this noise is referred to as “pattern noise” or “hot pixels,” and the 7D has a setting that helps to reduce this noise.
SELF-TIME YOUR WAY TO SHARPER IMAGES
Whether you are shooting with a tripod or resting your camera on a counter, you can increase the sharpness of your pictures by taking your hands out of the equation. Whenever you use your finger to depress the Shutter button, you are increasing the chance that there will be a little bit of shake in your image. If you don’t have a cable release to trigger the Shutter button, try setting your camera up to use the self-timer. To turn on the self-timer, just press the AF • Drive button and rotate the Quick Control dial until the selftimer icon appears in the top LCD Panel. (You can also adjust the Drive mode by using the Quick Control button located on the back of the camera as in Figure 7.9.) There are two self-timer modes to choose from: 2 seconds and 10 seconds. I generally use the 2-second mode to cut down on time between exposures.
TURNING ON LONG EXPOSURE NOISE REDUCTION
- Press the Menu button and locate the Custom Function screen.
- The Long Exposure Noise Reduction setting is located in the C.Fn II: Image section. Highlight it and press Set (A).
- Use the Quick Control dial to locate the Long Exposure Noise Reduction section (it’s the fi rst menu item), and then press the Set button.
- Use the Quick Control dial to select Auto, and then press the Set button (B).
- Press the Menu button twice to exit. This noise reduction will be applied to all images with exposures that are 1 second or longer.
- When using the Long Exposure Noise Reduction setting, you’ll notice some lag-time after taking each photograph. This is because the camera is working and reducing the noise in the most recent shot. You won’t be able to take another photo until this process is complete.
Now that the noise is under control, you need to determine the camera mode to use when photographing long exposures. When I photograph long exposures, I will use either the Av or Manual modes. Sometimes I start in Av so I can choose the aperture and then see what the camera thinks is the best shutter speed. After I take a few test shots to get an idea of what range works well, I switch into Manual mode and continue from there. You will probably fi nd that using manual focus is the best choice as well, since it will usually be too dark for your camera to fi nd focus on its own.