The Educational screen (c1922-c1956])

Page 278 The Educational Screen reasons why the back seats in a church are filled first. Semi-darkness at least partially relieves this situation. Because worship is emotional, when one feels the desire to sing or to pour out his heart in prayer to a sympathizing and understanding God he should not be restrained from full expression. When the point of interest is lighted in a semi- darkened room it is difficult for a person without conscious effort to keep his eye from being drawn to the lighted object. Just as birds of passage are attracted to a flashing beacon, so the human atten- tion is drawn and held by a properly lighted center of interest. \\ ith visual distractions reduced, reverence heightened, emotions released, and the attention held by an illuminated point of interest, it is rea- sonable to expect that worship should be more effective, more interesting, and that it should at- tract larger attendance. Considering these facts, aside from any values which pictures may bring into this atmosphere, projection in itself is an essential convenience for providing hymn lyrics and written sentiments which the congregation may desire to repeat together. And if pictures can be used as an artistic medium to emotionalize words in much the same way as music is used, or if pictures are used to recall experiences and to stimulate desirable vicarious experiences which are essential in identifying and appreciating the good and beautiful which comes from God or is God, and to the interpretation and understanding of these experiences, then pictures have an additional value and may be of inestimable aid in the conduct of public worship. Reversible Film Most of us take it for granted that everyone understands all, or nearly all, about reversible film —the film that is usually used with 16mm cameras. However, it might be well to reproduce here the following information on reversible film that re- cently appeared in Personal Movies magazine, in case some of our readers are not informed on some of the points discussed: "Reversible film is so named because the negative obtained after the exposed film is developed is sub- sequently reversed into a positive—the finished film being the original one that has been exposed in the camera. When the exposed roll of film reaches the laboratory it is developed into a negative. In the latter process all the silver halide particles of the emulsion which have been affected by light are re- duced to metallic silver. The remaining emulsion remains unaffected. The film is now subjected to a bleaching bath which dissolves away all the de- veloped silver grains leaving only the unexposed emulsion. It is then cleared of the bleach, resensi- tized, and exposed to light. After this second ex- posure the image is developed as a positive. The film is then fixed, washed and dried. "There are two kinds of reversible film available to the amateur: panchromatic and supersensitive panchromatic. Panchromatic film is more reason- able in cost and serves well for all-around work. It is sensitive to all the colors of the spectrum, having an excess of sensitivity to blue. Its speed is sufficient for most purposes. "Supersensitive film, as its name suggests, is faster than the type just mentioned. This, however, is not its outstanding advantage as man)' individuals are wont to think. As most of your filming is ac- complished outdoors in daylight, you have no doubt discovered that regular panchromatic film possesses sufficient speed to record the subjects you photo- graph. The superior advantages of the new super- sensitive emulsion lies in its improved color sensi- tivity which closely approximates that of the eye. As compared to the regular panchromatic film it has a 400 to 500 per cent greater sensitivity to the red, 200 per cent to the green and 75 per cent to the blue. This will enable a more correct rendition of the subjects you film. "The speed of supersensitive panchromatic film is rated as twice as fast as normal panchromatic film to daylight and three times as fast to tungsten light. The reason for its great speed with the latter type of illumination is due to the abundance of red in the light provided by the tungsten lamp. There- fore its real speed value to the amateur is obtained when using it indoors with mazda light illumination. Ordinary house lamps may be put into play to pro- vide sufficient light to take successful movies. "Another property of supersensitive film is that it is soft working. This has reference to the con- trast between the different tones in the finished film. A hard working emulsion produces contrasty results. There are decided dark and light portions. At times the results it produces appear snappy, at other times they may seem harsh. In a soft work- ing emulsion there is a soft graduation between the different tones of the images. Contrast may, of course, be present, but it is not very decided. Scenes will be reproduced in a more pictorial fashion, and portraits will be rendered more artistically. Normal panchromatic film is in itself not a hard working emulsion, but the supersensitive panchromatic film produces softer results. "Supersensitive film is of great value when em- ploying very heavy filters such as the A and F filters both of which are red. With normal pan- chromatic film the A filter would require a 10 to 12