American cinematographer (Jan-Dec 1940)

I Use Infrared FilmBy HATTO TAPPENBECK Photos by ivriter THE use of infrared film is not new to the Hollywood camerman, who has been using it for a number of years already. Since its appearance the stability as well as the speed of the film have been increased; and it is now available to professionals and amateurs alike. The infrared film is mostly sensitive in the infrared part of the spectrum well known under the name of heat waves. These are invisible to our eyes, but have the same eff'ect on the infrared film as the visible rays on a regular panchromatic emulsion. But the infrared film is sensitized also in the visible deep reds, in the full scale of the visible blues, and somewhat in the invisible ultraviolet rays on the other extreme end of the visual spectrum. From this it is at once apparent that the film will give a good reproduction of a landscape or person without the use of filters; at least equal to pictures made with orthochromatic material. With a yellow filter holding back the blues to some extent infrared film will produce a picture similar to one made on panchromatic film without filter. I mention this as we are more often shy at using infrared film, because its extensive use in motion pictures for effect shots has spread the idea that the film can only be used for that purpose. The results with this film for regular work is satisfactory as long as exact color rendition is not required. Available in 16mm. The infrared film has been made available by the Eastman Kodak Company in 35mm., in all sizes of cut film, and in many sizes of roll film for amateur cameras. It is of particular interest that it also can be had in 16mm., but only as a negative non-reversible film due to the characteristics of the product. This should be a welcome addition to the special effects department of the serious 16mm. worker. P'acilities for processing and printing are just as accessible as for reversal film. The Agfa Ansco Corporation has added to the professional infrared film a line of the most popular sizes in infrared rollfilm. The Time exposure of 1 second at f :3.5 on infrared film without filter. The illumination xvas furnished by the infrared rays of the electric stove with the addition of a 25 tvatt ruby darkroom lamp. This picture was taken in total darknesa with radiation from the stove only. Exposure 2 seconds at f:3.5, on infrared film. The steam of the boiling water reflects the infrared rays. specific qualities of all these infrared films correspond very closely. Infrared rollfilm will be an added attraction for many who want to explore the invisible. A very instructive booklet on the subject of infrared photography is put out by the Eastman Kodak Company. Infrared film was originally used for night shots in the daytime and in aerial photography. Since then many uses have been found for it in science as well as in industry. The speed of this film lies between 20 and 24 Weston, which amounts to slightly less than half the speed of the well known Eastman Plus-X or the Agfa Supreme Panchromatic films. The best time for getting night shots in the daytime is during the noon hour when the shadows are deepest. Side light or even backlight is essential. The effectiveness of the shot depends on the contrast between highlights and shadows. Lights burning in streetlamps, automobile headlights, etc., add realism. A thorough study of actual night scenes and buildings in the moonlight points the way. The main characteristic of a night shot is the black sky. With infrared we easily accomplish this by filtering out all the ultraviolet and blue rays. Filter Exposures A heavy red filter such as a Wratten 25A or 29F will usually be sufficient. For extreme night shots we use a Wrattan 70 or 72 filter; both have a filter factor of 10 for infrared, while the filter factors for 25A and 29F are 4 and 5 respectively. The stop in bright sunlight for a camera speed of 16 frames per second or approximately 1/30 of a second exposure will be f:ll without filter, f:8 with a K2 filter, f:5.6 with filter 25A, f :4.5 with filter 29F, and f :3.5 with a 70 filter. Exposure meters of various types depend on their readings for the visible American Cinbmatographer • November, 1940 515