Facts about Projection

[Music] so [Music] it's well known in education that only carefully planned instruction produces maximum learning planning is especially necessary to achieve maximum educational value for motion pictures this means proper study and discussion of the material in advance of screening and a follow-up of planned related activities the careful use of films in religious education just as in our schools speeds up the learning process and provides more learning in less time industry 2 has learned that planned use of films is one of the most effective methods of communicating ideas and teaching specific skills to show films there are a number of excellent and easy to operate motion picture projectors available there are minor differences in the operation of these projectors such as the method for threading the film replacing the projector lamp cleaning the film gate the location of the speaker or rewinding however all motion picture projectors operate on the same basic principles a sound understanding of these principles will provide a basis for operating any type of 16 millimeter projector [Music] a typical motion picture projector consists of two sections each with a different function the picture section which projects the picture from the film to the screen and the sound section which reproduces or recreates the sounds which have been recorded on the film soundtrack as the film moves through the projector it first enters the picture section this section consists of the projection lamp which is a very bright light source this light is concentrated on a single frame of the film by a condenser lens the brilliantly illuminated frame of the film is projected by the projection lens onto the screen the lens is moved to focus the picture as the film moves through the picture section it pauses on each frame in a sound projector this happens 24 times a second next the film enters the sound section here an exciter lamp passes light through the soundtrack area of the film this light is received by the photocell waves which have been recorded as variations of light and dark areas on this film cause the light beam reaching the photocell to vary in brightness when the film moves the photocell produces electrical pulsations corresponding to the original sounds which are then amplified and fed to the speaker in contrast to the picture section the film in the sound section must move smoothly and at a constant speed some motion picture projectors are equipped to record and reproduce magnetic sound this magnetic soundtrack coating often uses only part of the optical soundtrack area making it possible to use either optical or magnetic sound on the same film in the school the most effective use of films takes place in the classroom with its study atmosphere the class has already prepared work on the subject and before seeing the film there is discussion of the new ideas and words that will be used the teacher having read the film guide and having reviewed the film often leads the class in the discussion now they're ready for the film smooth professional projection in the integration of the film with the workaday atmosphere of the classroom greatly enhances effectiveness in learning but to achieve this professional screening there had to be proper preparation preparation in advance is the key to good projection in the majority of schools audio visual equipment and the films themselves are kept in a central location here under supervision the films are checked and if necessary repaired and the equipment is maintained much of the preparation behind good film use is in training operators in the principles of projection and in maintenance of the equipment some projectors are equipped with sealed long lasting oil reservoirs and seldom need oily but most projectors require regular lubrication the oil should be placed only in the proper holes or cups and any overflow carefully wiped away it's the same idea as lubricating one's automobile at regular intervals this preventive maintenance protects gears and moving parts from excessive wear if the windshield is dirty only a blurred image is seen a special fluid and paper are used to give a crystal clear view just so in cleaning the lenses of a projector remove grit and brush gently with a soft brush use a drop of lens cleaner then dry using a circular motion with lens cleaning paper a dirty lens projects a scene like this clean it and you have this this fuzz around the edge of the picture area is dirt in the aperture it is not only disturbing to see but it can scratch the film it may be removed easily with a brush the sound projector sprocket wheels have sprockets or teeth only on one side sound films have sprocket holes on only one side the soundtrack is on the other side to reduce strain on the film during projection the film is threaded with loops above and below the gate these loops serve as shock absorbers correct loop size is usually indicated on the projector if loops are too large they will slap about if they're too short they may tear the film about 95 percent of film damage happens in the first 20 feet the lower loop must always be the correct size and the film must fit snugly over the sound drum in order for the sound to be synchronized with a picture this is because the sound is recorded exactly 26 frames in advance of the picture properly threaded film appears like this on the screen the movement of my lips is synchronized with the soundtrack however if the lower loop is too short the voice will be heard like this in advance of its picture and the two will not be synchronized and if the loop is too long the voice as you hear it now will lag behind the corresponding picture and will again be out of synchronization if at any time the film should break in the projector do not patch it with tape or anything else simply overlap and continue winding so that later on at the film library the break will be found and repaired not only is understanding the technical operation and maintenance of equipment important but knowledge of proper projection setups covering varied situations is equally necessary the screen should be set up at the front of the room so that everyone can easily see it the screen should be placed at least two screen widths in front of the first row the bottom of the screen should be level with the tops of the heads of those in the front row if a room can be adequately darkened or if chairs are permanently fixed to the floor the screen should be placed at the front and center of the class some rooms are difficult to darken if this is the case it is best to place the screen diagonally in the corner of the room by the window in rooms extremely difficult to darken a lenticular screen placed in this position is most helpful to ensure a smooth running operation a supply of extra projection lamps exciter lamps fuses and belts should be on hand it's always a good idea to check the film before taking it to the room where it will be shown one way to do this is by placing the reel on the projector if the film is mounted on the reel properly it should fit on the arm so that it runs clockwise when held in this position the title should read correctly when the projector is started you won't have this or this picture will be right side up and in the proper position all films that are to be projected should be checked in advance with much of the preliminary preparation done in the audio visual or equipment room where supervision and the necessary equipment and supplies are available the final setup in the classroom can be made this time the projectionist is able to set up the equipment before the class has assembled often the setup must be made while the class is in session the screen is placed directly in front of the projector and raised to the proper height the projector is then assembled the power cord is twisted around the leg of the stand to prevent the projector from being tipped over if the cord is accidentally pulled if an extension cord is used it should be secured by a knot if the sound fails to operate it may be because the plug is reversed in the outlet the projector is ready for a trial run the motor is turned on then the lamp if the image is too large for the screen the projector must be moved closer and of course the reverse is also true for the best sound the speaker should be placed off the floor and near the screen the speaker cord is secured in the same manner as the power cord in a few moments the amplifier will warm up and a hiss will be heard to indicate that the sound system is working testing with a card is a double check on the sound system by leaving the cans open at the start the changes of reels could be made quickly it's always a good practice if time permits to actually view the beginning of the film in order to check the focus the framing and the volume [Music] when the classroom is filled with students the volume may have to be turned higher a signal from the teacher and the screening is started preparation in advance is the key to good projection it will result in a smooth screening of the film and this in turn will provide an opportunity for maximum learning [Music] [Music] you