The motion picture projectionist (Nov 1929-Oct 1930)

18 Motion Picture Projectionist Sharp clicks should not be heard after the first. A double click indicates a short circuit. Be very careful not to hold a hot soldering iron on this condenser, as this may ruin the insulation. If this condenser does indicate a short, replace it with another. If you do not have one on hand, go to the nearest radio store and purchase one. Careful Film Handling Every manager and projectionist should take active interest in eliminating the warping of motion picture film. However, this cannot be done without additional equipment and some expense. National cooperation in this matter is the only possible way of eliminating this difficulty, which is a general nuisance to those trained for good projection. Your attention is again called to the careful handling of film. It should be thoroughly understood by this time that film must be handled with the greatest of care. I still find many projectionists who are very negligent in keeping their projector and sound mechanisms clean and free from oil and dirt. I have pointed out before the importance of cleanliness. Dirt and oil on the film sound track will register in the reproduction. It is extremely important that motion pic ture film be kept perfectly clean at all times. Inspect the projector mechanism; do not allow the sprockets to become undercut. In many cases sprockets may be reversed and additional wear thus obtained. Do not allow the tension springs, which support the tension shoes, against the aperture to be set up too tight. A strain on the sprocket holes of the film will result. Film varies in thickness and the tension should be checked quite frequently. Idler rollers may not be revolving, and perhaps one of these rollers is responsible for scratching film ; maybe they are not lined up and set properly in relation to the sprockets. The fire trap valve rollers in the top and lower magazines should also be checked quite frequently. Aperture plates and film tracks must be in good condition. The responsibility rests with the projectionist for the condition in which picture film is returned to the exchange. Great care should be exercised in oiling the projector and sound reproducing mechanism. If too much oil is applied to the bearings, it is possible that this over-flow will find its way into the optical system that focuses the slit on the film sound track. This will result in loss of volume. (Continued on page 46) How to Properly Care for Lenses By Sidney Wein* EXTREME care should be exercised in cleaning projection lenses, for the reason that there are any number of things that may be done incorrectly which result in rendering the lens unfit for further use. One who is inexperienced in cleaning lenses might be expected to proceed as follows: With a handkerchief (soft-laundered or otherwise), he proceeds to rub the front of the lens while it is in the projector head — and it never occurs to him that the lens, to be properly cleaned, should be taken out completely. The procedure on the second lens is similar. All sorts of cleaning agencies are used — rags, tissue paper, dirty cloths full of grit — in fact, anything which is handy at the moment. Before any lens is cleaned, or rubbed with any substance, it should be thoroughly dusted with a fine camel-hair brush to remove the hard dust gathered from the lamphouse and the concrete floor. This dust_ is full of grit and, when rubbed in with a cloth, is an abrasive. A camel-hair brush costs one dollar, but it is worth many times that amount for this purpose. When a lens is rubbed with cloth or other similar material its surface is practically ruined, as the cloth acts much the same as emery cloth in rubbing into the lens the hard dust 'Local Union No. 306, N. Y. City. and dirt which has collected on the surface. Deep ruts in the lens surface result. Before rubbing any lens always use a fine hair brush to dispose of the surface dirt. Use of Liquids We know that one part of the lens combination consists of two lenses cemented together. If a liquid is used for cleaning purposes, do not soak this lens to clean it. Your liquid cleaner may dissolve the cement on the combination lens, or if there is a slight opening in the cement, the liquid (by this time mixed with the oil and dust on the lens), will seep in and, after it dries, leave a film of oil inside the combination that no amount of rubbing will take out. Whenever a liquid is used, dampen a very soft cloth and wipe, don't rub, the lens, immediately after which the surface should be wiped with a piece of fine chamois. Lenses should be polished, and there is a special paper available for this purpose. In reassembling the lens remember that all bellies (convexes) , go to the screen side; all hollows (concaves), and all the flat sides (pianos), go to the lamphouse side. Position Lens Tightly Inside of the lens barrel there are threaded rings to hold the lenses in place. These rings should be screwed up so tightly that there is absolutely no play. One idea that has had wide circulation and considerable credence attached to it is that lenses, like condensers, must have ample play or they will crack when subjected to heat. This idea has no foundation in fact. The moving film acts as a heat absorbent, and the glass in the lens will not readily crack as a result of the heat that does filter through. What is more important is that these loose lenses have a tendency to throw the picture in and out of focus and ruin definition. The more the projector vibrates the more the lenses dance in their jackets and the more they are thrown out of line with each other. Such a condition violates every law of optics and the resultant screen picture is anything but complimentary to the projectionist. Serves As Oil Trap It will be noticed that the back part of the lens jacket, while holding no lens, has a very fine thread cut through its whole length on the inside. The purpose of this end of the jacket is to prevent oil from splashing on the lens; and the thread on the inside serves the very useful purpose of an oil trap, each thread serving as a little alley in which to imprison any oil that may seep into the jacket and prevent it from rolling down to the lens. Wipe out this section each day with cheesecloth. Gummed Labels A gummed label pasted on the film facing you with the number of that reel marked in large type on it and the name of the picture in smaller type (where double features are used), will help to avoid the possibility of picking the wrong reel from the bin when in a hurry. Some absent-minded projectionists even today hang a large "ess" hook on the handle of the bin containing the next reel to be used. Record Marking Mark the number of every record in bold figures with a china marking pencil on each disc. When two soundon-disc features are used the same day, put the name of the feature on the disc together with the number. This will avoid confusion. Torn Sprocket Holes When sprocket holes are torn on one or both sides of a film the usual procedure is to cut out all the frames on which the torn sprocket holes are bordering. Where sound-on-disc is used this means putting in the annoying blank film to compensate for the film taken out. A better method is to cut from a transparent leader film a strip about %-inch wide to include the whole sprocket holes. Patch this alongside the torn sprocket holes so that hole covers hole properly. This will give a first-class job with no annoying blanks.