Movie Makers (Jan-Dec 1936)

471 Which film? CARL LOUIS GREGORY PERSONAL movie makers are puzzled sometimes by the question of which film to use. However, it is quite safe to say that most brands of film offered for sabs — and all those offered by reputable companies — are of very high quality and will give excellent results when they are used for the particular purpose they are intended to serve. But their use presupposes an intelligent selection of the particular kind of film most suitable for the task in hand, its proper employment and a proper treatment, afterward, in processing. No single film can cover the range of all kinds of cine work any more than one grade of printing paper can be suitable for all kinds of negatives, or one kind of film or plate desirable for all kinds of photographic work. The price of film is not a guide to its suitability for any certain kind of movie making. Price often must enter into consideration, especially in commercial work, but sometimes the lower priced film is best for the job, while, on the other hand, the highest priced film may be the only one that will give satisfactory results and is. therefore, cheaper in the end. All substandard film is coated on acetate, or non inflammable, base. One need not fear, in using unfamiliar grades of substandard film, that a fire hazard will be created. The film base is the same, and it is the light sensitive emulsion coating on that base which determines the film's photographic qualities. Of the many kinds of reversal film advertised, and which can be purchased with the processing charge included, there are five general classes. These are color blind positive, orthochromatic, regular panchromatic, supersensitive panchromatic and color film. Color blind film is lowest in price and slowest in speed, but, for the amateur who seldom bothers with filters, who is not hypercritical about color values and subtle tones and who shoots exteriors only, under good light conditions, it is very satisfactory and economical. It lacks a non halation backing, so that halation is often present when light objects are filmed against dark backgrounds. Orthochromatic is a term derived from two Greek words. ortho and chroma, meaning right and color, that is, right color or correct color. The word is a survival from the dark ages of photography, when motion pictures of any kind were only a bright dream of the future. The first emulsions made for photography were slow and sensitive to blue light only. That depends upon the purpose to be served by its use Green, yellow, red and the other combinations of the warmer shades at the lower end of the spectrum had almost no effect on these emulsions and were consequently rendered as tones of very dark gray or black. Tone values of colored objects were rendered in half tones that were quite different from their brilliancy as seen by the eye. When it was discovered that certain dyes, added in small amounts to the emulsion, increased its sensitivity to yellow and green very markedly, the resultant film was christened ''orthochromatic," because it reproduced colors in gray tones more nearly right, or correct, as viewed by the eye. Today we regard panchromatic as much more suitable for correct rendition, but the old term, orthochromatic, is still applied to film which is most sensitive to blue and to the upper register of the color scale. Orthochromatic film requires about the same exposure as ordinary panchromatic and about two times as much as supersensitive panchromatic. Orthochromatic is sensitive mostly to blue light, and slightly to yellow, but is almost insensitive to green and red. Of course, color blind positive is also insensitive to red. This means that, when color blind or orthochromatic film is used, all reds will appear dark on the screen. Filters can be used with orthochromatic film, but only certain types may be employed. In bright sunlight, the lighter colored, yellow correcting filters may be advantageous. Dark colored, yellow filters should not be used with orthochromatic film, because they cut down the light, to which the film is sensitive, so much that a fully timed exposure cannot easily be made. An exception is made to the ban on deep toned filters, when moonlight effects are made by pointing the camera toward the sun for waterscapes or clouded sunsets. Here, underexposure is intentional, and the use of a heavy filter not only cuts down exposure, but tends to reduce the halation in the highlights. Red filters must not be used with orthochromatic emulsions. In the main, where there is an abundance of natural light and where tonal values of colored objects are not highly important, orthochromatic film gives [Continued on page 490] Publishers' This scene calls for supersensitive panchromatic film