When you are taking photos in low-light situations, you will fi nd that the camera’s autofocus doesn’t always work. But before you can properly and consistently fi nd focus in these instances, you need to understand how your camera’s focusing system operates.
First, you should know that when you are trying to focus on your subject, the camera utilizes contrast in the viewfi nder in order to establish a focus point. If you were to point your camera at a clean, blank wall and try to focus it right in the center, the lens would hunt around and probably not fi nd focus (Figure 7.6). By moving the focus point to an area where there is contrast, the camera will be able to set focus much more quickly (Figure 7.7).
If your subject doesn’t have enough contrast for the camera to read, you can always use the “focus and recompose” method of shooting if you fi nd an area of contrast that is at the same distance as your subject. To do this, press the Shutter button halfway to set focus, and then—with the button still pressed halfway—recompose your shot in the viewfi nder. When you have it composed how you like it, press the Shutter button fully. The focus should stay where you originally set it.
Another option is to use the manual focusing system. If you are photographing something that is diffi cult to focus on, like fi reworks, you should set your camera’s focusing manually. If you point the camera into the dark sky, the autofocusing system will just keep searching for—and not fi nding—a focus point (Figure 7.8). To set your focus manually, just fl ip the switch on the lens from AF to MF and rotate the front of the lens until your focus is set.
Another way to ensure good focus is to enable the 7D’s Focus Assist mode. This setting uses the fl ash to send out short bursts of light on your subject to help the camera in locating detail. If you don’t want to use the fl ash, you can disable it while you take your photos—the fl ash would only be used temporarily to help fi nd focus but wouldn’t actually appear in your shot. If you are using the Full Auto or Creative Auto modes, this feature is automatically enabled.
TURNING ON THE FOCUS ASSIST FEATURE
- Press the Menu button and then use the Main dial to get to the Custom Function menu tab.
- Rotate the Quick Control dial to highlight the C.Fn III: Autofocus/Drive setting and press the Set button (A).
- Use the Quick Control dial to get to the eleventh item, the AF-Assist Beam Firing section.
- Press the Set button and select Enable, and then press Set to lock in your choice (B).
- Press the Menu button twice to exit, and then press the Flash button located on the front of your camera. Now with the fl ash in the “up” position, press the Shutter button to focus and activate Focus Assist.
If you don’t want the fl ash to fi re during the actual exposure, you must fi rst disable the fl ash.
DISABLING THE FLASH
- Press the Menu button and then scroll the Main dial to highlight the fi rst camera setup tab.
- Scroll down to Flash Control and press the Set button (A).
- Set the Flash Firing option to Disable (B).