How Motion Pictures Move and Talk

[Music] the scope of a motion picture is tremendous it brings to us the life of Colin Lyons and strange people the highlights of current events history in the making in war and peace from the laboratory the progress of science great industries tell their magic stories modern business uses the screen to teach and to sell the theater screen gives pleasure and enlightenment to millions every day in homes all over the land the smaller movie cameras and projectors give happiness to the entire family the pictures which we take ourselves perpetuate priceless memories of the changing years this thing certainly seems to move but by stopping and starting the action we see that it is really the result of a series of slightly different pictures passing quickly before the eye an optical illusion created by our persistence of vision you can demonstrate this for the car on one side a bird on the other a cage curl the card and the bird appears to be inside the cage because your eye holds each image briefly after it has gone in the infancy of movies this principle was adapted with paper pictures of progressive action run rapidly on a revolving wheel for an audience of one in the historic scene shown here appears the inventor of the first talking motion picture Thomas a Edison beating some of his fellow pioneers in the march of the movies the drawings from which animated cartoons are made show us how persistence of vision is applied to the screen there is no more motion in any one of these drawings than on a postage stamp but on each one the action is slightly advanced if the series is flipped fast enough the picture seems to move these pictures are photographed and printed on a long transparent strip of celluloid film when running a projector they come to life the essential parts of the projector are a pre focused light source easily replaced an optical system consisting of condensers adjustable reflector and a quick focused lens readily removed for cleaning and a sturdy film moving mechanism built like a fine watch let us look behind the scenes as we greatly slow down the running speed normally this shutter revolves well over 4,000 times a minute here in numbers take the pace of pictures so that you can readily follow the film as it moves when the black blade momentarily obscures the light part of the shutter blade is now removed so that you can watch the shuttle to that work note that the strop that shifts the film is a cycle of four separate clear-cut movements straight in down then out and back up the shutter revolves three times for every picture change thus cutting down each dark period to less than five one thousands of a second this gives added brilliance and eliminates flicker on the screen normally the film moves very fast but absolute accuracy assure steadiness of the picture on the screen this eliminates eyestrain gradually now let us bring the speed up to normal 24 pictures every second here we have repeated each number 24 times so you can watch it change the film moves freely in its channel it is held steady by side tension batches are those avoided because there is no pressure on the delicate film surface the camera used to photograph this picture works very much like the projector except that the light from the outside reaches the sensitive film through a sharply focused lens the precision of the camera must be matched by the accuracy of the perforations in the pill these punches produce the sprocket holes that control all film movements through every subsequent mechanism a steady running camera and accurately punched film make it possible to superimpose two pictures to form a single composite scene here is a good example the actors were photographed in Hollywood the background a street scene was taken in another city the slightest movement error in either camera would have spoiled the interesting effect now let us see what makes the movies talk the sound is reproduced from a track on the side of the picture this is a variable density track one of the two sound systems in general use and this a variable area track either can be reduced to the smaller 16 millimeter film their operation in the sound projector is similar the film passes through a sharply focused beam of light coming from the exciter lab with the volume control we turn this light up and the sound becomes louder as the soundtrack of the film passes through the beam it creates constantly changing light impulses [Music] these are transformed into minut electrical currents by means of a photoelectric cell then greatly amplified to become audible through the loudspeaker let us see how the sound was actually photographed on this film the recording of my off-screen voice such as you hear in newsreels for instance is done after the picture film is edited we are testing and getting ready to record in the recording room they thread up for a take my voice will be recorded on this separate negative the monitor man at the control board modulates the tone and volume of the recording I am here at the microphone reading from my script against the picture action on the screen my voice sets in motion air particles which strike the sensitive diaphragm with a sound wave pattern that is transmitted into corresponding electrical vibrations these are increased in volume thousands of times in the amplifier for with variable area recording they must attain sufficient strength to vibrate a tiny mirror which reflects a ribbon of light through the optical system to create a constantly changing vibration pattern on the sensitive film my words that have been recorded on the soundtrack appear like this as I am now speaking to you from the screen many of you perhaps never realized that boys and sound can actually be seen with on-screen sound the picture and sound negative are made at the same time so that the action and voice are exactly matched in Hollywood at the grand national studios we see a well-known star in action [Music] developing of the negative film is done in intricate machines but the basic principle involved is much the same as the way you develop snapshots in to solutions and wash waters [Music] the picture is then printed after the print is developed it is cut and edited often from as much as a quarter of a million feet of exposed film less than 8,000 feet will be selected to make up the finished picture then the picture negative and soundtrack negative are matched and printed together on a single film called the composit red this is the completed production finished to thrill audiences and theaters all over the world [Music] [Applause] for smaller projectors 16 millimeter prints of these same pictures are made from the standard negative on a reduction printer because these smaller prints are less than 1/4 the area of the standard film extreme accuracy is absolutely necessary for good results here is a 10 real feature production on 35 millimeter film which when reduced to 16 millimeter gives us an equal amount of picture with less bulk less weight and absolute safety from fire hazards you can now buy or rent hundreds of these motion pictures silent or with sound educational subjects to Hollywood features it is possible for anyone to show motion pictures anywhere anytime the magic picture that moves and talks now comes to your screen at your command [Music]