Abstract: An apparatus for precisely moving a camera lens element to focus an image at the camera's film plane is disclosed. The apparatus employs an electrically controlled and incremently stepped rotating motor which moves a lens element parallel to the lens axis. The disclosed motor is an epicyclic motor, and a mechanical coupling arrangement interconnects a driven rotating motor element and the lens element holder and converts the rotary motion of the motor to incremental translation of the lens element. The apparatus moves the lens element in this manner in small precisely controlled increments, for example, steps of less than 0.001 inch.

Abstract: A Sell-type transducer for use in an ultrasonic ranging system for a camera has a hollow base containing a floating backplate having a grooved surface in contact with the non-metallic surface of a metallized plastic diaphragm stretched across the base. A spring arrangement urges the floating backplate into engagement with the diaphragm to maintain tension thereon in the event long-term plastic flow occurs in the diaphragm. Improved side lobe suppression is achieved by progressively decreasing the depth of the grooves as the periphery is approached. Further, for repeatability, the crests of the grooves define a convex surface.