An outdoor, battery powered digital camera includes a passive infrared motion detector that allows the camera to be left unattended, as the detector automatically triggers the camera to take a picture upon sensing the presence of a moving animal. To prolong the life of the battery, the camera goes into a power-saving sleep mode between pictures. To enable the camera to instantly take a picture upon suddenly being awakened by the motion detector, the exposure setting of the camera is periodically checked, adjusted and stored so that the camera can use that fairly recent exposure setting, or one near it, to take an instant picture rather than wasting excessive time adjusting the exposure when the animal first appears. In some cases, the camera is used in conjunction with picture management software.