Film and TV Technician (1957)

52 FILM & TV TECHNICIAN April 1957 A Technician's Notebook NEW GATE MECHANISM • CINEMIRACLE • FRENCH LENSES RECENTLY I was invited to look at a very interesting modification of an Arriflex camera; nothing less than the fitting of a completely new gate mechanism incorporating a double claw pulldown and register pins. it is the outcome of enterprise and initiative on the part of the technicians in a documentary unit who felt that there was a need for a light portable camera with a standard of performance generally associated only with heavy studio equipment. They were fortunate in having as enthusiastic collaborator a young engineer who, convinced of the practicability of the idea, set to work, designed and produced the gate which has now been given the name P.F.P. The P.F.P. gate has all the appearances of being built to good engineering standards. The film is pulled down by double claws, operated by two cams which ensure that the claws enter and withdraw from the perforations at right angles to the direction of film travel. The two register pins are also driven positively by a cam, and do not use return springs. Improved Definition The back pressure plate is also cam operated and clamps the film in the focal plane during exposure. I was assured that this has produced a considerable improvement in definition; and, because the back pressure plate is retracted while the film is being pulled down by the claws, one of the main causes of negative scratch is eliminated. The Arriflex camera to which the gate has been fitted has been in use on a production, and to date about 20,000 feet of film have been shot, with entirely satisfactory results in respect of steadiness and definition. As proof of this we were shown on the screen shots taken at various stages of the production. Also screened were double exposure steady tests of the displaced cross type, and split screen shots, with both horizontal and vertical splits. They were an impressive demon stration of the accuracy of the registration of this gate. As one might expect with a movement employing a moving back pressure plate it is rather noisier than the standard Arriflex By A. E. Jeakins gate, but it was stated that the gate could be made quieter running by changes in some of the details of its construction. Because of the fact that the pressure plate works positively by a cam and is not spring loaded some adjustment would be necessary to accommodate a thicker film stock like Eastmancolor. Another feature of the P.F.P. gate worth noting is that though the modification was carried out on a Model II camera, tests have revealed that it works equally well with the II. A with its larger shutter opening. As the II and II. A shutter mechanisms are interchangeable, this has obvious advantages. The cost? It is estimated this would be about £300, with a delivery time of roughly six weeks. Anyone interested to know more about the P.F.P. gate should get in touch with Clifford Cameras and Equipments, 1 Soho Square, W.l. Cineniiracle Cinemiracle, the newest of the super wide-screen systems, uses three cameras in one photographic unit and three projectors interlocked to produce a picture with a horizontal angle of 146° on a giant curved screen. Unlike its predecessor in the same field, Cinerama, only one projection booth is used. According to an article in "American Cinematographer " by Joe Henry, on which these notes are based, demonstration screenings in Hollywood showed perfect blending of the three sections of the picture on the screen with no " jiggle " between them. National Theatres are behind this new process, on which development was begun in 1952. The Mitchell Camera Company built the camera unit, which consists basically of three cameras mounted on a base plate. The centre camera shooting straight ahead records the central panel of the triptych, the two flanking cameras set at an angle photograph the left and right hand panels through mirrors. "The American Cinematographer" article says that an important feature of the set-up, responsible for the excellent photographic results, is an interlocked electronic control linked with the SmithDietrich lens system, but does not go much further in explaining what this system is. As in Cinerama, a six sprocket hole film frame is used. Single Booth As mentioned above, the three projectors for showing the Cinemiracle pictures are housed in a single booth. The centre projector screens the centre section of the picture, and the left and right hand panels are projected by machines set at right angles to the centre projector and projecting through mirrors which are adjustable to the fine limits necessary to produce the illusion of a single panoramic picture on the screen. The projectors are fitted with 8,000 ft. spool boxes. The sound track is on a separate magnetic film and runs in sync, with the picture on equipment interlocked with the projectors. The Cinemiracle screen used in the demonstration measured 63 ft. by 26 ft. with a maximum curve of 13 ft. at the centre; covering a field of vision 146° wide and 55° wide. The first Cinemiracle feature. Cinemiracle Adventure, is in course of production. The story is concerned with the last of the square