Home Movies (1942)

PACE 232 HOME MOVIES FOR )UNE iVItat beg^inner^ should know about FILTERS B y STANLEY A N D R W I [N spite of increasingly wider use of color film, there is still much cinefilming done with black and white. Indeed filmers are legion who prefer panchromatic over color film and the reason for this choice is the dramatic results obtainable with black and white film when filters are employed. Because of the tremendous appeal of color and the fact that many who have taken up the hobby of home movies during the past two years started film ing with Kodachrome, most movie amateur beginners have yet to experience the fine pictorial results to be obtained in filtered cinematography. Invariably one's interest in filters is aroused upon witnessing the screening of some outdoor film in which fleecy white clouds have been made to stand out vividly against a dark sky. But filters can do more than this. They generally improve all black and white outdoor photography. £. J. thenmcier In order to understand the function of filters, it is necessary first to understand the characteristics of each type of black and white film. This was explained at length in the third article of this series appearing in the March issue and if convenient, it should be reviewed again at this time. For a long time there was but one type of film available for motion pictures. This was orthochromatic, insensitive or "blind" to all but a few colors in the blue-violet region of the spectrum. Later development resulted in orthochromatic materials of higher sensitivity. About 1900, it was discovered that certain dyes, when added to film emulsions during preparation, altered their sensitivity. Thus was developed the emulsions we know now as panchromatic and whose sensitivity covers about the same range as the human eye. In other words, panchromatic film "sees" natural colors in approximately the same tonal range as does the eye. Through the addition of dyes in the emulsion formula, panchromatic emulsions are made to register with marked tonal fidelity, colors of orange and red — at the other end of the spectrum — not "visible" to orthochromatic film. Thus by producing a film which is sensitive to colors, it became possible to intensify or correct certain color values by filtering the light reaching the film. Science tells us that white light actually is formed by a mixture of colored light. TTiis being true, it fol lows that colored light may be formed by breaking the white light into its component parts. Thus if a green filter is placed in the path of a ray of white light, only green light passes through the filter and the red and violet-blue colors are absorbed. If a red filter is used, only red light is transmitted and the remaining colors in the spectrum are absorbed in an action that is better understood as selective light transmission. It becomes understandable, then, why a red filter placed over the lens of a camera loaded with panchromatic film will accent white clouds in a clear blue sky. The red light in the clouds — and • Continued on Page 244 • This is the kind of beauty filters impart to movie scenes. Here a red filter was employed with panchromatic film to gain the effect of moonlight.