Journal of the Society of Motion Picture Engineers (1930-1949)

Jan., 1930] PROBLEMS OF WIDE FILM PICTURES 55 tion of general definition due to residual aberrations which become the more noticeable the longer the focal length. Now, it would not be strictly necessary for the production of the wide film pictures to have lenses as short as 50 mm. in focal length. If the distance from camera to set could be chosen at will, any given area which can be photographed with the desired reduction on a film of given size can be photographed at the same scale of reduction on a film of the same size with a longer focus lens. Two obstacles present themselves however; first, the distance from camera to set becomes too great involving excessive expense in studio space and, second, the perspective of the view becomes flatter. The latter might be overcome by a different arrangement of the set but this FIG. 3. Reproduction of 23 mm. X 46 mm. shot made with 50 mm.,//2.2 Raytar lens. again involves increased expense as compared with the possibility of varying perspective by the simple process of selecting the camera lens of most appropriate focal length. After the pictures have been taken the problem of projection offers difficulties in illumination and in finding a projection lens competent to project them with satisfactory definition. It is obvious that if the same amount of light which passes through the aperture of the film gate in an ordinary projector be spread over a screen area twice as large the illumination of the screen image will be only half as great. If a pair of ordinary 4x/2 in. condensers and high intensity arc be employed in their usual adjustment it will be found impossible to illuminate an area 23 X 46 mm. The illuminated