Nikon D5100 Reference Manual - Page 58

3 Choose a focus mode. Highlight a focus mode and press J. To return to shooting mode, press the shutter-release button halfway. A Predictive Focus Tracking In AF-C mode or when continuous-servo autofocus is selected in AF-A mode, the camera will initiate predictive focus tracking if the subject moves toward or away from the camera while the shutter-release button is pressed halfway. This allows the camera to track focus while attempting to predict where the subject will be when the shutter is released. D Continuous-servo Autofocus When Focus is selected for Custom Setting a1 (AF-C priority selection; 0 158) and the z camera is in AF-C mode or 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 45) or use focus lock (0 44) 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. Example: Subject is the same color as the background. The focus point contains objects at different distances from the camera. Example: Subject is inside a cage. The subject is dominated by regular geometric patterns. Example: Blinds or a row of windows in a skyscraper. Example: Subject is half in the shade. Background objects appear larger than the subject. Example: A building is in the frame behind the subject. The subject contains many fine details. Example: A field of flowers or other subjects that are small or lack variation in brightness. 40