An apparatus for providing left and right eye images along the axis of a single camera lens (7), the apparatus comprising optical means arranged to provide said left and right eye images (22, 20) as a pair of head-to-head or toe-to-toe images, i.e. with the two images (20, 22) separated by a center line and with either the tops of the two images (20, 22) or the bottoms of the two images (20, 22) adjacent the center line, so that the left and right eye images (22, 20) can be simultaneously recorded onto a single frame of a photographic film or other recording medium.