International projectionist (Jan 1941-Dec 1942)

liers of cinematic effect are opened up by making the screen area the entire proscenium wall, by employing a projector lens that will throw the 35-mm. frame to cover this whole wall as a potential, and by selectively limiting the projected image to smaller pictures within this potential, using peculiarly appropriate or eccentric delimitations in an overall montage of boundaries. Such a production can be imagined, described, and even accomplished with present-day equipment. A NOTE ON THE PROCESSING OF EASTMAN 1302 FINE-GRAIN RELEASE POSITIVE V. C. Shaner Eastman Kodak Company A brief historical resume is given of a series of fine-grain films that have been put upon the market during the past four years. This series of fine-grain films culminated with the acceptance of Eastman 1302 finegrain release positive at one Hollywood laboratory to the exclusion of regular positive <if the 1301 type for release printing. Experimental data are presented to show the comparative sensitometric characteristics of fine-grain positive 1302 and regular positive 1301 at various pH values and potassium bromide concentrations typical of Hollywood positive developers. A basic positive developer formula derived from chemical analyses of every release positive developer in Hollywood was used in the experimental work. Some practical facts are discussed, based upon the experiences obtained from the initial use of the fine-grain film in Hollywood. A CONSTANT TORQUE FRICTION CLUTCH FOR FILM TAKE-UP William Hotine The Rotovex Corporation From the standpoint of film protection, a take-up 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 constant-torque 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 take-up spindle, maintains this torque at a constant value 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 Corporation 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 theatre. 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. Projector Mechanism Design Analyzed The design and operation of the geartrain 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 singleand double-shutter operation are outlined and the actual opeiating results expected and realized discussed. ECONOMIC AND TECHNICAL ANALYSIS OF ARC LAMP AND SCREEN LIGHT CHARACTERISTICS Henry D. Behr 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 conslant 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. A FREQUENCY-MODULATED CONTROL TRACK FOR MOVIETONE PRINTS J. G. Frayne and F. P. Herrnfeld ■ Electric Research Products, Inc. ■ A 5-mil. frequency-modulated track located between sound and picture areas is proposed to control reproduction in the theatre from one or more sound-tracks. A variation of approximately one octave in the control frequency provides a 30-db change in volume range which may be used in part for volume expansion of loud sounds or as noise reduction for weak sounds. The control-track frequency is varied manually and recorded simultaneously with the sound-track in the dubbing operation, the gain of the monitoring channel being varied in accordance with the control frequency to produce automatically the enhanced volume rang* desired from the release print. How Track Is Recorded The track is recorded in line with the standard sound-track and does not require separate printing or reproducing apertures. It is scanned by a separate photosensitive surface, the output being converted from frequency to voltage variations by a frequencydiscriminating 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. 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, pre and post-equalization, finegrain 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. 26 INTERNATIONAL PROJECTIONIST