Analog computer simulation of accommodation

Over the past fifteen years the authors have evaluated numerous models of accommodation. Their task is to clarify these models by designing an automatically focused camera, with major emphasis of the capability of the retina to sense blur and feed this information back to the eye's lens for accurate focal adjustment. Depth-of-field, or dead-band, poses a significant obstacle for the designer of an automatically focused camera. The authors' approach is to use noise to provide a scanning, or dither motion so that the lens will spend 80 percent of its time in sharp focus. Retina detection of blur can be simulated by a Charge Coupled Device (CCD), designed to produce a null when sharpest focus is achieved. The nature of blank-field accommodation is judged, and a prediction made about its long-term behavior.