Nikon EN-EL9 D5000 User's Guide (English) - Page 73

D Continuous-servo Autofocus In AF-C mode or when continuous-servo autofocus is selected in AF-A mode, the camera gives priority to shutter response 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 60) or use focus lock (0 58) 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. Example: Subject is half in the shade. z The focus point contains objects at different distances from the camera. Example: Subject is inside a cage. Background objects appear larger than the subject. Example: a building is in the frame behind the subject. The subject is dominated by regular geometric patterns. Example: A row of windows in a skyscraper. The subject contains many fine details. Example: A field of flowers or other subjects that are small or lack variation in brightness. D The AF-Assist Illuminator If the subject is poorly lit, the AF-assist illuminator will light automatically to assist the autofocus operation when the shutterrelease button is pressed halfway. The AF-assist illuminator will not light during continuous-servo autofocus or manual focus, in shooting modes in which the AF-assist illuminator can not be used, or if Off has been selected for Custom Setting a2 (Built-in AF-assist illuminator; 0 155). The illuminator has a range of about 0.5-3.0 m (1 ft. 8 in.-9 ft. 10 in.); when using the illuminator, use a lens with a focal length of 18-200 mm and remove the lens hood. AF-assist illuminator A The Beep Speaker Custom Setting d1 (Beep; 0 158) can be used to turn the beep speaker on or off. 55