Abstract: In a method for focusing a reproducing objective, such as may be used for measuring distances, wherein multiplication of the image of the entrance pupil is achieved by image-splitting optical elements mounted in the plane of the object image, the improvement comprising:Projecting the light fluxes from different parts of the pupil image plane on separate sets or groups of photoelectric receivers, deriving a signal from the comparison of the output signals from these receiver groups and using this signal as a criterion for focusing as a function of magnitude and sign. Apparatus for performing the method includes a grid of prisms or pyramids, and a beam splitter for directing light through two separate photoelectric receiver masks.

Abstract: A stationary casing of a mechanical mounting for interchangeable lenses which are to be used with a motion picture or still camera is provided with first connecting terminals for electric connection arranged in a space within a coupling adapted to mate with a coupling of the camera housing. Second connecting terminals are also provided for electric connection arranged in a space within a coupling adapted to mate with a coupling of an interchangeable attachment unit. The first and second connecting terminals being electrically connected to each other through respective insulated wires provided in the stationary casing. Such a casing structure permits selection of interchangeable attachment units such as those incorporating a zoom-drive mechanism, an automatic focus-adjusting mechanism and an automatic diaphragm drive mechanism for use with the mechanical mounting.