The Cine Technician (1953-1956)

February 1956 CINE TECHNICIAN 21 A Technician's Notebook NEW POLYESTER FILM BASE A BULLETIN to hand from the firm of DuPont in U.S.A. gives the latest news of their new " Cronar " polyester film base, which, after eight years of research, is due on the market some time this year. This base is not only considerably thinner but also far stronger than any in use at present. DuPont forecast that it will make possible smaller rolls with greater footage in aerial cameras, that the thinner film will give new sharpness in the fields of photolithography and photoengraving, and that motionpicture film that is less subject to deterioration will last longer, yet occupy less space on the reel. TAKES PLACE OF GLASS Apart from its extreme toughness and durability, " Cronar " is also dimensionally stable. Even under varying conditions of temperature and humidity, it will register accurately time after time. It can take the place of glass or metal plates as a support for a sensitised emulsion and still provide the stability required for exacting performance with greater convenience and less expense. While ordinary film base breaks down with the passage of time, "Cronar" being almost chemically inert and containing neither solvents nor plasticizers, will remain stable and clear after many years, subject only to the care expended in developing and washing the sensitive image before storage. This should make it an ideal medium where films are stored for archival and record purposes. With particular reference to its use in aerial photography, tests under flight and laboratory conditions produced no film breakage at temperatures ranging from — 50 °C to +83°C. Experiments were carried out with the "Fastex" high speed camera to test the durability of " Cronar " based motion picture film. A .004 inch " Cronar " film was run at normal temperature through this camera at 8000 frames per second, and with temperature lowered to — 50°C at 5000 frames per second. No failures resulted with the DuPont base, ■By A. E. JEAKINS whereas conventional film bases did not pass this test. In connection with the research and development of its new film base, DuPont has worked out a new method of splicing motionpicture film, which is applicable to any type of base. The new process uses a special transparent tape, perforated to match the film to be spliced, and coated on one side with a pressuresensitive adhesive. Using "Mylar" polyester film .001" in thickness as the transparent tape, splices are stronger than required for any normal use and are not visible in projection. Both butt and lap splices can be made with this method. The bulletin describes three different machines designed to use this system. A NOTHER approach to the prob-^ lem of getting better picture definition on the big screens of to-day has been made by 20th Century Fox in filming Carousel in 55mm. CinemaScope. The camera used was a conversion of the Fox 70mm. "Grandeur" wide screen camera developed round about 1930. Aperture and race plates were converted to the 55mm. size and the existing narrow CinemaScope perforation dimensions have been retained. While 55mm. projectors are being designed, the only prints available are standard 35mm. CinemaScope reduced from the 55mm. negative which can be shown on existing projectors equipped for projecting CinemaScope. Even with these reduction prints it is claimed that there is an improvement of about 50% in clarity and definition. The 55mm. CinemaScope frame has an 8 perforation height giving a picture with four times the area of the 35mm. film. The photographic lenses used are naturally doubled in focal length over what is normally used. " In filming Carousel," says Charles Clarke in an article in the December issue of the "American Cinematographer," " I used 75mm., 100mm. and 152mm. coupled CinemaScope lenses. The 100mm. lens is considered the ' normal ' lens and was used for the majority of scenes. We used 152mm. lens for close shots and the 75mm. when an extremely wide angle was required." The camera and blimp weigh about the same as the Technicolor camera and blimp so that the velocilators, tripods and crane apparatus evolved for Technicolor production could be used. A 900 foot-candle key lierht at f4.8 was used on night interiors and a 1000 foot-candle key at the same stop for day interiors. At this aperture all the depth desirable was obtained. A.C.T. FILMS A.C.T. Films will commence production of The Jury at Nettlefold Studios on March 5th. Terence Fisher has been signed as director, with John Gossage producing and Desmond Dickinson lighting. The Jury is based on the famous novel by Gerald Bullett. Ralph Bond, who is in charge of A.C.T. Films, tells us that this production is the most ambitious that the company has lined up since The Final Test. It is being made in association with Warwick Films, for Columbia distribution, and the stars are Tom Conway and Elizabeth Sellars. Some of the best known British artistes will be featured in supporting roles.