Nikon D3100 D3100 User's Manual - Page 72

3 Choose a focus mode. Highlight a focus mode and press J. To return to shooting mode, press the shutter-release button halfway. D Continuous-servo Autofocus In AF-C mode or when continuous-servo autofocus is selected in AF-A mode, the camera gives higher priority to focus response (has a wider focus range) than in AF-S mode, and the shutter may be released before the in-focus indicator is displayed. A Getting Good Results with Autofocus Autofocus does not perform well under the conditions listed below. The shutter release may be disabled if the camera is unable to focus under these conditions, or the in-focus indicator (I) may be displayed and the camera may sound a beep, allowing the shutter to be released even when the subject is not in focus. In these cases, focus manually (0 62) or use focus lock (0 60) to focus on another subject at the same distance and then recompose the photograph. There is little or no contrast between the subject and the background. The focus point contains areas of sharply contrasting brightness. z Example: Subject is the same color as the background. Example: Subject is half in the shade. The focus point contains objects at different distances from the camera. Background objects appear larger than the subject. Example: Subject is inside a cage. Example: A building is in the frame behind the subject. The subject contains many The subject is dominated by fine details. regular geometric patterns. Example: A field of flowers or Example: Blinds or a row of other subjects that are windows in a skyscraper. small or lack variation in brightness. 56