An auto-focus camera has an optical system for forming an image of a target, a moveable sensor for recording a set of one or more images of the target, the set of one or more images corresponding to a set of one or more positions for the moveable sensor, and a linear piezoelectric actuator mechanically coupled to the moveable sensor for driving the moveable sensor to the set of one or more positions along a predetermined moving direction in response to a stimulus. A driving system is actuable to generate the stimulus to drive the piezoelectric actuator. An image processor, in response to stored instructions, obtains the set of one or more recorded images from the moveable sensor, processes the set of one or more obtained recoded images, and identifies the image that is in focus.