American cinematographer (Oct 1933)

228 American Cinematographer • October 1933 Recording Sound On 16mm Film Eric M. Berndt Editors Note: Because of the strong belief that the 16mm is going professional in an industrial way and that the 16mm camera will in time turn professional for that field, we have asked Eric M. Berndt, manu- facturer of the only sound on film 16mm camera to give his views and a description of his camera. B EFORE the introduction of 16mm sound on film, it was considered by many either impossible or impractical to obtain satisfactory sound reproduc- tion from 16mm film. However, the great success and popularity achieved by the 16mm projectors for sound on film, in the field of non-theatrical motion pictures, refutes this. The interest in 1 6mm sound is very great, and three of the projector manufacturers have met this demand with sound on film projectors which are noteworthy for their simplicity of design, ease of operation, portability, and na- tural reproduction of sound. In conjunction with the in- creased screen illumination now incorporated in 16mm pro- jectors, pictures may be shown in large auditoriums. More and more subjects are being made available, con- sisting mainly of reductions from existing 35mm films. These reductions are of high quality pictorially and good sound is achieved either by re-cording or optical reduction. 16mm sound pictures have also been made directly on the 16mm film. The advantages of photographing industrial, educational, and scientific pictures directly on the 16mm film are quite evident, especially from the standpoint of equipment, operating costs, and processing. It is extremely interesting to note that the cost of film and processing for 400 feet of 16mm, which is equal to 1000 feet of standard, is approximately $27.00, either by using reversal or nega- tive-positive system. In step with the development of 16mm from purely amateur to more academic and professional uses, the profes- sional 16mm sound on film camera, shown in the photo- graph, was built. The camera was designed to photograph sound and picture simultaneously on 16mm film, and to enable the cameraman to obtain professional effects and re- finements in his 16mm films equal to those achieved by the use of 35mm professional cameras. The camera illustrated is provided with 1000 foot maga- zines, or 400 foot magazines as desired. The 1000 foot magazines permit a continuous run of 28 minutes to be made, equal to 2500 feet of standard. The camera and magazines are made of cast aluminum and finished in chromium trim and black crackle. It may be had with 110-volt A. C. synchronous motor, or universal 110-volt governor controlled motor. Provision is made for hand cranking at eight frames per turn, or one frame per turn. The intermittent movement is silent in operation. The At top the Berndt Sound on 1 6mm film camera. At bottom the cased electri- cal equipment. sound sprocket is highly filtered in order to obtain a perfectly uniform flow of film past the recording optical. Since 16mm film travels at a speed of 36 feet per minute, it is necessary that a camera of this kind be built to the highest standards of mechanical accuracy. Some of the camera features are the four lens turret with standard lens mounts, variable view finder, focus on film with 1 OX magnified upright image, frame counter, footage counter, reverse take-up, optional dissolving shutter, and etc. The accessory electrical equipment is carried in two cases, one containing the recording amplifier and batteries, and one for the condenser microphone, cables .earphones, etc. A single 864 is used in the head amplifier, and five stage cascade 864’s with a 1 71A for power output. The amplifier has a gain of about 85 DB, is stable in operation, and free of microphonic disturbances. Compensation is in- corporated for high frequencies lost by film characteristics and printing. Variable area was chosen as the most suitable type, for 16mm recording, because of its easier processing. It also eliminates the large number of B batteries required for glow lamp. Many films require careful attention in processing, when taken under unfavorable photographic conditions. With variable area recording, more attention can be given to the picture, since processing variations will not affect the track as much as they would if it were a density track. The recording system consists of an exciter lamp, an improved type of mirror galvanometer, and an optical system which projects the oscillating beam of light onto the film forming a slit of .3 thousandth. A rheostat and milliameter serve to regulate the exciter lamp intensity, so that the proper exposure for the different emulsions may be achieved very easily. A visual monitor is incorporated which permits the oscillating beam of light to be observed, magnified, through the film, and permits checking the amount of modulation, (Continued on Page 235)