Moving Picture Age (Jan-Dec 1922)

MECHANICS o/VISUALIZATION A Department Conducted by AUSTIN C. LESCARBOURA, ^7sSm?A Managing Editor of ' merican In this department appear each month discussions of the important materials of visual instruction — projectors, films, stereopticons, slides, screens,, cameras, lenses, and other items of equipment on which the non-theatrical exhibitor should possess authoritative and impartial information. It should be distinctly understood that all expressions of opinion emanate from Mr. Lescarboura, and that Moving Picture Age take9 no stand upon the opinions expressed in this department. ?What problems are handicapping you in your visual in* st ruction work? Mr. Lescarboura stands ready to answer by correspondence the questions of any subscriber pertaining to equipment, when the inquiry is addressed to him at the office of Moving Picture __ Age and is accom *W panied by stamped, f addressed envelope • — The Editor. THE PROFESSIONAL PROJECTOR THE LAST type of projector to be reviewed in our brief survey of projecting equipment is the professional or theatrical machine, which represents the highest development of projection. It is the type that must be used when the requirements are beyond the scope of the semi-professional type and the other types of projectors. On the other hand, it should be resorted to only in instances where the smaller and less expensive types will not do. Primarily, the professional type is a theatre machine. It is intended for use where the audience runs up into the thousands and, consequently, a large screen must be filled. It must be used in large auditoriums, for large outdoor shows, and for large churches. Its use calls for a fireproof booth and a licensed operator, if the various state and municipal ordinances are to be complied with, not to mention the fire underwriters' rulings. The operation of a theatricaltype projector is obviously more involved than that of the smaller machines, hence it calls for a higher degree of mechanical skill. There are various offerings of the professional type, but in no other instance is the standardization of motion-picture apparatus as marked as in professional or theatrical projectors. Essentially, the usual offering has a heavy stand, a large lamp house, a motor drive, enclosed fireproof film magazines, and the intermittent mechanism. Of late years the incandescent type of lamp house has been gaining ground, and it is recommended in preference to the arc lamp for small and even moderate throws. It is simpler to operate, the cost is lower, the screen results are more uniform, and the lamp is noiseless, emitting no fumes and giving off far less heat. The operating conditions are considerably more healthful and comfortable. Using the usual celluloid film, the professional projector has every possible safeguard against a film fire. It is provided not only with fireproof magazines and fire-quenching rollers that prevent a fire from getting into them, but also with some form or other of fire shutter that swings out of the path of the beam of light from the lamp house, and permits it to pass through the film, only after the latter has attained a sufficient speed. Should the speed drop below a point considered safe, the fire shutter drops down into the path of light and cuts it off from the retarded film. The motor drive is regular equipment with professional projectors, but if desired the hand drive only may be used. The latter form is preferable when the projector is to be used for traveling shows, in which case there is insufficient current supply for operating the motor as well as the lamp. For traveling shows, too, it is possible with most offerings to obtain an aluminum pedestal or stand so as to reduce the weight materially without affecting the solidity of the machine. The price of the professional type of machine may range all the way from $370 for the smaller hand-driven models, up to $500 and over for the heavier, motordriven models. The Simplex Professional SOME POINTERS REGARDING INCANDESCENT LAMPS THE ARC lamp is doomed, so far as projection equipment is :oncerned. Up until a short while ago it was generally believed that the arc lamp would survive for large theatre installations where the throw and the size of the screen were extremely large. But recent I I I I 1111 Pinhole image of Filoment on fire, shutter Method of Testing Adjustment of Reflector So That Reflected Imaqe of the Filaments Appears between the Actual Filament Images developments have demonstrated beyond ■■■■■■■■■■■■■■■■ a doubt that in the very near future we shall have incandescent lamps available for any throw any size of screen. Meanwhile, the purposes of non-theatrical projection, in which we are primarily interested, can best be served by the incandescent lamp. An incandescent lamp has certain inherent advantages over any other form of illuminant. Once the light source is correctly located at the focal point of the condenser, it stays put. For this reason it is not necessary to use a larger source than the minimum required to obtain results, thereby saving current. Freedom from color and shading effects at the edges of the screen is also obtained by reason of the light source remaining fixed. It does not require constant attention of the operator. The light from the incandescent lamp is steady, tending to reduce flicker. It is emitted in that portion of the spectrum to which the eye is most accustomed and most sensitive ; therefore, it is neither trying nor tiring. Of course it is clean and noiseless. Carbon arcs make considerable noise with their sputtering and humming, and give off considerable carbon dust, which is apt to scratch the films and cause wear of the machinery parts. No fumes are emitted by the incandescent lamp, and the amount of heat given off is lower than with other types of illuminants. The incandescent lamp works equally well on alternating and direct current, and it enables the use of the more efficient two-wing shutter. But the advantage of the incandescent lamp that appeals most strongly to the projectionist is the ease of control. Expert knowledge is necessary to set up the outfit and keep it in satisfactory condition, but the actual operation requires less attention than the arc, thus allowing the projectionist to pay more attention to the projection of the picture itself. In addition to all these advantages, the cost of operation is less than with other light sources. For example, if a 40-ampere direct-current arc, operating from a motor-generator, is replaced by a 900-watt incandescent lamp operating through a transformer, and assuming that the machine operates ten hours per day, and pays 6 cents per kilowatt hour for power, the total power consumed for the arc lamp and control equipment will be 2,600 watts, and this, added to the carbon renewals, will amount to $751.90 per year; as compared to a power consumption of 990 watts for the incandescent lamp, this, added to lamp renewals, bringing the annual total cost up to $345.81. There are several sizes of Edison Mazda lamps available for use in professional and non-professional types of projectors. For theatre use and large auditoriums, .where a 12-foot to 16-foot picture is desired, the 30-volt 30-ampere, or 900-watt, bulb is the most suitable. For large churches, schools, and so on, probably the 30-volt 20-ampere, or 600-watt, bulb will be satisfactory. For smaller dimensions of screen image such as in 6-foot, 8-foot, and 10-foot pictures, there are the 250-watt, 110-volt bulb, the 300-watt, 28-32-volt bulb, the 400-watt, 110-125-volt bulb, and the 1,000-watt, 110-125 volt bulb. These bulbs can also be employed for stereopticon lanterns. A 1,000-watt, 110-volt bulb will give excellent results in the stereopticon. According to Mr. L. C. Porter of the Edison Lamp Works of the General Electric Company, Harrison N. J. (to whom we are indebted for this data), nothing can contribute more to the success or failure of the incandescent lamp in projection service than the alignment of the various elements in the optical train. The instruction sheets accompanying each projector show the One Type of Projector ArsSWi Image of Filament and mirror image 16