International photographer (Jan-Dec 1941)

photosensitive surface, the output being converted from frequency to voltage variatons by a frequency-discriminating network identical to that used in the monitoring channel. The output from the network, applied to the grid of a variablegain amplifier in the sound channel, controls automatically the volume of the reproduced sound in accordance with that observed in the dubbing operation. The Design and Use of Film Noise Reduction Systems; R. R. Scoville and W. L. Bell, Electrical Research Products, Inc., Hollywood, Calif. Methods of increasing the signal-to-noise ratio in film recording that have been extensively developed in recent years include the following: use of double-width push-pull sound-tracks, preand post-equalization, fine-grain film, noise-reduction bias systems, squeeze-track, volume compression and expansion, and control-tracks. The principles underlying the use of such systems are treated, and the manner of combining them to obtain the most effective noise-reduction is shown. The design of noise-reduction bias systems is explained in considerable detail and the application to a new unit is described. Although this information has largely developed from the variable-density method of recording, much of it is also applicable in the variable-area system. Streamlining a Sound Plant; L. L. Ryder, Paramount Pictures, Inc., Hollywood, Calif. This paper discusses the trend in modern sound-recording equipments. It reviews the objectives and requirements that are now existing in regard to studio recording as contrasted to previous recording systems. Several new developments in the art of sound recording are discussed and from this group are selected a complementary series of improvements which together are streamlined into a new recording plant. A Precision Direct-Reading Densitometer; M. H. Sweet, Agfa Ansco Corp., Binghamton, N. Y. The history of physical densitometers is briefly discussed. In spite of developments in modern electronic circuits, simple photoelectric instruments suitable for routine sensitometry are not yet in common use. The present densitometer is designed to fill this need. The minimum requirements for a satisfactory instruments are outlined. Photographic density as such, and destiny standardizations are discussed. The densitometer density of the present instrument as related to that of other types is demonstrated. The opitcal aspects, including the geometry and spectral qualities of the system, are explained, and the problem of calibration discussed. Emphasis is placed upon the practical agreement of different optical systems suitably calibrated, and specific examples are shown. The circuit arrangements of previous photoelectric densitometers are outlined. The theory and practical development of the present electrical circuit are described, and the effects of the novel features are shown. An accurate linear density scale is obtained in a single-stage d-c amplifier, and the sensitivity is sufficient to permit the use of a rugged output meter. A density range of 0 to 3.0 is covered, and the characteristics of the output meter are given. CINEX Light Testers — Polishers used by all Major Studios. We are the sole Manufacturers and Distributors. Manufacturer of 16mm and 35mm Recording Heads, Developing Machines, Bipack Color and Black and White Printers, Rewinds. Special Machinery built to order. CINEMA ARTS-CRAFTS 914 No. Fairfax HE 1984 Hollywood, Calif. Cable Address: "CINEBAKSAM" The technics used in prior densitometers in attempting to secure a linear density scale and adequate scale length for good legibility are discussed, and the technic used in the present instrument is compared with them. The performance characterstics of the electrical circuit make it suitable for application to recording instruments. The routine operation is described and the permanence of calibration is shown. Data are given on the warm-up period and drift, and on the influence of varying line voltage. Operation is entirely by alternating current. Practical performance considerations such as convenience in reading, eye fatigue, etc., are reviewed, and figures showing the comparative speed of operation and reading accuracy are given. A Review of the Question of 16mm Emulsion Position; Wm. H. Oetenhauser, Jr., Precision Film Laboratories, New York, N. Y. When a 16-mm sound-film is properly threaded in a 16-mm projector, the emulsion of the film may face the screen (which position is called the "standard"' position) or it may face the projector light-source (the "non-standard" emulsion position). The well-designed 16-mm "standard" or "non-standard" prints. In the case of 35-mm film, the standard position for the emulsion of a print is opposite that for 16-mm; in 35-mm, the emulsion faces the light-source of a projector. The anomaly of the 16-mm emulsion position around from the fact that a large number of the earliest 16-mm commercial sound-films were made by optical reduction from 35-mm negatives. Since the "standard" was established, however, numerous developments have occurred in direct 16-mm production which now practically compel the recognition of so-called "non-standard" prints as a factor of fast-growing importance in our rapidly growing 16-mm industry. The expression "non-standard" emulsion position no longer carries the stigma ordinarily associated with other things that are called nonstandard. Motion picture films may be printed either by contact ( the emulsion of the film to be copied is in physcal contact with the raw film upon which the copy is to be made) or by optical printing (the emulsion of the two films are not in physical contact; some form of lens system is interposed between the film to be copied and the raw film upon which the copy is to be made). By far, the largest percentage of picture film printed today is printed by contact methods. It does not seem likely that 16-mm picture film will be printed optically in the near future for a number of reasons, not the least of which is the lack of available lenses due to the defense program. The use of Kodachrome duplicates has been growing very rapidly and since contact printing of Kodachrome originals will continue to be used for some time, the "non-standard" emulsion position will continue to be a rapidly growing factor in 16-mm sound-projection that can not be ignored. Some Equipment Problems of the Direct 16mm Producer; L. Thompson, The Calvin Company, Kansas City, Mo. The production of industrial films by the direct 16-mm method is now definitely out of the experimental stage. As more industrial work is done by this method there is an increasing demand for more and better 16-mm equpment suitable for professional use. Such equipment can be developed successfully only after the professional user has found by actual experience what he needs and wants. A number of 16-mm professionals were asked for suggestions as to what is needed. These suggestions, combined with the author's own ideas gained over a period of 10 years in the professional 16-mm field, form the basis of this paper. Some of the ideas presented could be acted upon immediately; some of them can not be put into practice until the demand for 16-mm service becomes even greater. A Constant-Torque Friction Clutch for Film Take-Up; William Hotine, The Rotovex Corp., East Newark, N. J. From the standpoint of film protection, a takeup mechanism should be reliable, wear should not appreciably alter its characteristics, and it should maintain the film tension between safe limits. These objects are attained by driving the take-up spindle through a const anttor que clutch of novel construction and design. A new type of friction-clutch is described, which, when adjusted initially to deliver a given safe torque to the takeup spindle, maintains this torque at a constant value of which can not be exceeded. The clutch construction is simple and rugged, and wear of the friction element does not appreciably affect the operation. Due to the fact that the torque at the take-up spindle is maintained at a constant value, a safe value of film tension is not exceeded. An analysis of the forces and mechanical constants of the clutch mechanism is given, deriving an equation of these in terms of torque delivered. Recent Developments in Projection Machine Design; E. L. Boecking and L. W. Davee, Century Projector Corp., New York, N. Y. This paper discusses the design features of a new projector to meet the ever-increasing demands for accuracy and simplicity required by modern projection in the theater. Basic, fundamental, scientific functions of motion picture mechanism design are discussed relative to perfection of film motion, clearer definition, light transmission, and picture steadiness. As in the design of any scientific mechanical device, the stability and inherent durability must first begin with perfection in the basic design and it must be built upon a foundation of engineering knowledge proved by practical operating experience. In order that these design features may be appreciated it will be the purpose to show how every step of the engineering design, every part of the mechanism, and every motion were carefully planned so that mechanical perfection could be achieved. The design and operation of the gear-train are discussed with respect to its simplicity, mechanical accuracy, and long life ; the design and operation of the bearings are reviewed in the light of recent developments relating to permanent operation with minimum servicing; and the intermittent movement operation is analyzed in relation to more stable operation and steadier picture reproduction. The film-gate and film-trap design, providing more uniform film travel at less film tensions, is described as well as methods of obtaining perfect placement of the film plane with respect to the optical axis. Finally, the theoretical design features of single and double-shutter operation are outlined and the actual operating results expected and realized discussed. Economic and Technical Analysis of Arc Lamp and Screen Light Characteristics; H. D. Behr. New York, N. Y. Many exhibitors do not understand what is meant by the relative inefficiency of power for ultimate consumption at the arc in comparison to power actually delivered at arc. Deficiencies in various parts of the projection plant are described and a value is placed upon losses to emphasize the need for constant attention to details. Tables are presented showing the excessive carbon and current costs that result when arcs are operated at higher currents due to defects in equipment. Emphasis is placed upon the fact that too many arcs operate at or near the upper limits for which they were designed and too little leeway is left for extra current to increase light for dull prints or color prints. Some ideas are given as to what to look for in competitive arc equipments. Various procedures are described for minimizing current and carbon waste due to poor reflector mirrors. Suggestions of projectionists have too long been ignored by managements. The latter should take a little time from their booking and other problems to ascertain that poor screen light is costly and definitely contributes to drops in attendance. 22