Moving Picture Age (Jan-Dec 1922)

MECHANICS o/VISUALIZATION A Department Conducted by AUSTIN C. LESCARBOURA, SSiSLlan 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 takes no stand upon the opinions expressed in this department. ?What problems are handicapping you in your visual in* str uction 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 *M panied by stamped, I addressed envelope • — The Editor. Schematic Arrangement of the Optical Components of a Projector Using an Arc Lamp as the llluminant THE FIVE GENERAL TYPES OF PROJECTORS THE PROJECTOR, like any other piece of machinery intended for a serious purpose, must be fitted to the job. It would be sheer folly to equip a traveling salesman with a standard theatre projector. Such a machine weighs many hundred pounds ; and, outside of the fact that a motor truck would be necessary to transport the outfit from place to place, such equipment is too elaborate and too powerful for the showing of films to a small audience. Equally foolish, although not quite so obviously so, would be the use of a portable-type projector in a large theatre; for such a machine, it goes almost without saying, would not stand up under the constant and trying service of a regular theatre program, and the picture which it projects would not be sufficiently large and bright to give the proper screen effect. So let us not forget that there is a general type of projector for each specific class of motion-picture work. There is no such thing as a truly universal projector. Once the job for the projector is fully understood, one should decide on the proper type of projector to fit that work, and then search the offerings of that particular type until the desired machine is obtained. To do otherwise is merely to court disappointment. Our correspondence always includes a fair sprinkling of letters from schools, churches, and industrial organizations that have installed the wrong type of projector for the work in hand; yet all this trouble and disappointment could just as well have been avoided in the first place. After all, it does not seem such a difficult matter, once the various types of projectors are properly classified and a definite field of activity assigned to each type. Of projectors there are five general types, ranging all the way from the big professional machine employed in our regular picture theatres, to the small machines for home use. The first type, then, is the large professional machine, for which a licensed operator and a fireproof booth are required, according to the rules and ordinances existing in many localities. This type of projector is represented by half a dozen makes. The more elaborate models, such as are to be found in our leading picture houses, are provided with motor drive, extra large film magazines, and automatic arc feed. As far as nonprofessional work is concerned, this type is only to be considered for large auditoriums and for certain kinds of outdoor work. Where the audience numbers upward of several hundred persons the large professional machine is generally necessary in order to fill a large enough screen ; but only in cases of absolute necessity should the regular professional projector be considered. Then we come to the second type — the semi-professional type. Compared with the theatre projector, the cost of which may be $500 or more, the smaller semi-professional projector generally runs from $250 to $350 in price. Some offerings include a stereopticon attachment, which is a valuable consideration since it permits of the showing of lantern slides with the same machine, and therefore increases the usefulness of the machine. Schematic Arrangement of the Optical Components of a Semi-Professional or Portable Projector, Using an Incandescent Lamp UPPER CARBON CONTROLS LEFT: Typical Incandescent Lamp Equipment for a Professional Projector RIGHT: Carbon Arc Stand Employed in Professional Projectors The semi-professional type is nothing more than a boiled-down copy of the larger professional machine, with the mechanism and controls reduced to the simplest terms. It can be operated by anyone with but a few instructions. Yet this type of projector is quite capable of projecting a fair-sized screen image of sufficient brilliancy for an audience of a few hundred persons. Practically all the offerings of this class are provided with motor drive, so that the operator has merely to thread the film and press a switch, and the machine does the rest until the film has been run through. Again, all machines of this type use an incandescent lamp as the illuminant, instead of the arc lamp employed in most professional projectors. Where large screens are to be brilliantly illuminated, there is no substitute for the carbon arc. In moderate-sized installations it is possible and quite feasible to employ the incandescent lamp, which entails a considerable saving in current consumption and makes for simpler operation. But in all the semiprofessional projectors and in the remaining types to be described the arc has been entirely superseded by the high-efficiency incandescent lamp ; and it is this feature, more than any other, that has made the non-professional types a success. Just compare the mechanism of the arc with that of the incandescent lamps shown in the accompanying illustrations, and the facts are immediately evident. Then we come to the suitcase type, which is strictly a portable proposition. This type, because of its very lightness and compactness, must of necessity lack some of the advantages of the larger machines. Thus it would not be good policy to use such a machine in a large auditorium as a regular installation, for that application should really be reserved for the semi-professional type. But when it comes to showing pictures in the classroom, clubroom, church, and even in the home, the suitcase type is at its best. It throws a smaller picture than the semi-professional type, of course, and the lighting is not so brilliant if the screen image is made too large. The wear on the film and the likelihood of trouble are apt to be greater than with the semi-professional type, owing to the double loop used in threading many of the offerings in this class. Still, this type has received no little attention from motion-oicture engineers, and the present offerings are far superior to the first suitcase projectors, which made their appearance some five or six years ago. The suitcase projector is ideal for classroom use. It can be carried from one room to another, and its mechanism is the essence of simplicity. Every precaution is taken to make such machines as safe as possible, and the film is entirely enclosed in a fireproof case. Furthermore, with the steadily increasing use of standard-sized slow-burning film the suitcase projector becomes absolutely safe. On special order the suitcase type can usually be obtained for use with narrow-width slowburning film, known as the safety standard and the Pathescope. Now for the fourth type, namely, the narrow width or safetystandard type. With the advent of slow-burning or acetate-of-cellulose films, as distinguished from the usual celluloid or inflammable -UPPER CARBON LOWER CARBON 18