Cine cameras, both 16- and 35-mm. size, record their images in a rectangular frame, the height measuring the shortest diameter (Fig. 1, A). As cine-radiographic images are circular in shape, it is apparent that the maximum diameter which may be recorded is restricted to the height of the rectangular frame. In order to obtain a reasonable compromise, it is frequently necessary to overframe the image (Fig. 1, B). This may result in a loss of as much as 50 per cent of the vertical dimension of the image, whether on 16-or 35-mm. film. After subtracting the space utilized by side perforations, the useful frame size of 16-mm. film is 7 1/2 × 11 mm., and 18 × 26 mm. for 35-mm. film. Some gain in the width of the frame may be achieved through the use of single perforated 16-mm. film by utilizing the unperforated edge. However, while this adds approximately 2 mm. to the width of the frame it obviously is of no great value in cineradiography as it does not extend the critical vertical diameter of the conventional f...