The Motion Picture Almanac 1929 (1929)

114 The MOTION PICTURE ALMANAC 1929 WALTER CAMP, President JOHN BOYCE-SMITH, Vice President E. C. JENSEN, Sales Manager INSPIRATION PICTURES INC. Executive Offices 565 Fifth Ave., New York Production: Tec-Art Studios 5360 Melrose Ave., Hollywood, Cal. HENRY KING'S "SHE GOES TO WAR!" featuring ELEANOR BOARDMAN ALMA RUBENS JOHN HOLLAND AL ST. JOHN Adapted by Fred de Gresac from the novel by RUPERT HUGHES Scenario by Howard Estabrook Directed by Henry King The epic of woman's imperishable part in the Great Conflict Produced in association with Victor and Edward Halperin INSPIRATION PICTURES, INC. Released through United Artists but volume has nothing to do with whether it be high or low. You all know that it is the string of a violin vibrating under the bow that causes the sound you hear. You also, 1 think, know in a somewhat less understanding way that it is the vibration of a disc to which the phonograph needle is attached that causes the sounds you hear from the phonograph horn; also that it is the aforesaid needle riding in a groove that causes the needle to vibrate exactly as a similar disc was vibrated by the air waves when the record was made, so that waves or vibrations exactly similar in every way to the waves or vibrations which operated the taking disc are reproduced in the air by the phonograph disc. That is comparatively easy to understand, but sound on the film is another story — and a much more difficult one to describe intelligibly without consuming a great amount of space, supplemented by many photographs. I will, however, do the best 1 can with the difficult subject. * * * In this case the problem is to transform air vibrations into electrical vibrations and those in turn into light vibrations and then in their turn into photographic densities in a form which will permit of them to be again transformed into light densities which may be transformed into electrical vibrations and those latter vibrations themselves transformed into air vibrations of exactly the same frequencies and values of the original air vibrations or sound waves which originally set the various operations into action. Remove your chapeau.x — ladies as well as men — out of respect for those men who have given us apparatus of such unbelievable accuracy that such a train of sequences can be carried through with error tolerances so small that even the most minute variations in sound are reproduced with apparent perfection. In recording sound by photography, the process is very roughly, as follows: A "microphone" similar to those used in radio broadcasting, receives the sound waves upon the face of its "diaphragm," a metallic sheet only one line-thousandth of an inch in thickness, lience very sensitive to any pressure exerted against it. The waves cause it to vibrate with precisely their own frequency (number of vibrations per second), and slightly or heavily according to whether the sound has heavy or light volume. It then follows that these vibrations are an exact duplication of the sound waves themselves, both in the matter of frequency and depth of vibration. When I say "slightly or heavily" it must be understood that we are dealing with thousands of an inch, or with fractions of one one-thousandth of an inch. To the nude eye the "mike" disc would appear to remain perfectly stationary and rigid. These vibrations are, by the action of the condenser (old type microphones used a different type pick-up, but I believe all now use the condenser, which is much more delicate and accurate) transformed into electrical vibrations in a circuit connected with an "ampli fier," which is really not an amplifier at all, but merely a device by means of which a very weak current is made to control a very much heavier current, and to cause it to assume vibration characteristics exactly the same as its own. But we now arrive at a parting of the ways, because different producers use different types of apparatus to transpose the resultant electric vibrations into light, and to cause that light to be delivered to the negative film in the motion picture camera. One uses a "Neo" lamp, which is a lamp so made that when it is burning, a halo of highly sensitive gas surrounds its filament and forms a highly atonic light source, the brilliancy ot which changes with every variation in the strength of the exciting current. In considering this latter it will be necessary to draw upon the imagination in the attempt to understand the literally enormous rapidity of the action of electricity and light. tJnless you can accomplish that you cannot possibly grasp the possibilities for the density of illumination of such a lamp varying in say one one-millionth of a second, which is exactly what actually takes place. Remember we are now changing electrical vibrations controlled or set up by air vibrations carrying sound into light intensity variations, which same are made to impinge upon a narrow strip at one side of the film, first passing through a "slit" formed by two knife edges fixed microscopically one and one-half thousandths of an inch apart. This slit is about one-tenth of an inch long. We then have a horizontal line of light of the above dimensions, which is by lens action reduced somewhat when it strikes the film. We then have a line of light say one-thousandth of an inch thick by one-tenth of an inch long (NOT accurate measurements) striking one side of a negative film as it passes through the motion picture taking camera. You know that the impression made by light upon a negative film will depend upon (a) the time the light shines upon the film and (b) the brilliancy and (c) the actinic value of the light. All right! The time of exposure is fixed by the speed the film moves past the slit, which is at the rate of ninety feet per minute. The actinic value of the light is fixed, hence its brilliancy is the only factor to be considered, and that is gauged by the value of the current at the time, measured in millionths of a second, which value is in turn gauged by the vibrations of the microphone disc. We then will have in the form of variation in photographic densities what amounts to a photographic representation of the microphone disc vibrations, or in other words of the sound waves, when the film is finally developed. Another method, now being used by some producers, is to gauge the amount of light incident upon the sound track of the film (negative) by means of what is called a "light valve." This "valve" is a contrivance having an electrically operated slit which opens and closes, thus permitting the passage of a greater or less amount of light.