A method and apparatus for determining the direction the taking lens of a camera should be moved in order to provide a proper focus condition. A plurality of radiant energy detectors are positioned to receive energy from a scene being viewed and a first group of such detectors produces a first output signal pattern while a second group of such detectors produces a second output signal pattern. The two patterns coincide at the desired focus position but move with respect to one another in a first or opposite direction depending upon the focus condition. The slope of one or both of the patterns at predetermined positions is multiplied by the difference in value from the outputs of the detectors to create values which are summed. The sign of the summed values is representative of the direction the taking lens must be moved to bring the patterns into coincidence at the desired focus position.