1. A system for converting a film camera into a digital camera, comprising: an image sensing array; a read-out circuit coupled to the image sensing array; a memory coupled to the read-out circuit for storing a digital picture derived from an image read-out from the image sensing array; an audio sensor for detecting sounds within the camera; and an acoustic pattern recognizer that compares signals received from said audio sensor to determine if the signals correspond with acoustic patterns associated with shutter operation, said acoustic pattern recognizer having a training mode that can be used to develop a set of acoustic patterns associated with shutter operation based on signals from said audio sensor during said training mode; and said image sensing array having a low power listening mode and an image capture mode and being configured to switch from said listening mode into said image capture mode when the pattern recognizer recognizes an acoustic pattern associated with shutter operation.