16 mm film

“ This is known as the Edison Standard Gauge, and it is observed by practically all the motion-picture firms in the world.
175 The perforations along the edges of the films furnish the means for drawing them through the camera, printing machine, and projector; and as the correct movement of the films is one of the important factors in making good pictures, they must be absolutely mathematically exact. A fault in perforation of even as much as one thousandth part of an inch is apt to cause the film to buckle in the camera or projector and ruin the whole thing. ”

“ If one does not care to purchase a lens, a small 1-1/2 in. or 2 in. reading glass can be used, if it is stopped down, or a lens may be taken from a hand camera. The width of the camera from front to back (W, Fig. 2) must be determined by the focal length of the lens. The dimensions given in the drawing are only approximate, and they can be changed if the camera is to be used in making an extra long film negative.
The roll of unexposed film (A, Fig. 2) is placed on a small shaft between U-shaped bearings, made of sheet metal and screwed to the top board of the camera. ”

“ I might explain, briefly, that moving pictures are taken not by pressing a switch, or a rubber bulb, such as that which works a camera shutter, but by the continuous action of a crank, or handle, attached to the camera. Pressing a bulb does well enough for taking a single picture, but when a series, on a long celluloid strip, are needed, as in the case for the "movies," an entirely different arrangement becomes absolutely necessary.
The sensitive celluloid film must move continuously, in a somewhat jerky fashion, inside the dark light-tight camera, and behind the lens. ”

“ A regular lens fitted in a metal tube can be purchased from a moving-picture stock house at a reasonable price. The box is made up similar to the camera box, but with a metal back instead of the wood. The intense heat from the light would quickly burn the wood and for this reason the light should be kept from the film while it is not in motion. The projecting lens barrel should be fitted snugly, yet loose enough for focusing. ”

“ And thirty-five millimeter, huh? Did you find a cartridge or a spool?” He listened for another moment and then said “Sure. Thanks, Chief,” and hung up.
“I guess you all heard that.” There was a note of triumph in Sandy’s voice. “They found a six-inch scrap of thirty-five-millimeter film in the wastebasket. My guess is it’s the remains of a roll for a candid camera like mine.”
“That still doesn’t make it an incendiary job,” Bert said firmly. “Probably some customer of Sam’s had just picked the roll up at a drugstore, where he was having it developed. ”

“ Serviceability and reliability are the outstanding features of the low-priced camera, and it is applicable to almost every branch of the craft.
Contrary to general belief, taking the "movies" is quite as simple as snap-shot photography with a Kodak. In the latter case you press the button; in the former you turn the handle; the camera does the rest. The rotation of the handle, a simple operation, performs every duty through the internal mechanism. It swings the shutter across the lens, moves the film intermittently through the instrument, and coils up the exposed film in its dark box. ”

“ Upon the top of the frame is bolted a two horse-power electric motor which is driven by a set of storage batteries; the combination of the turntable with a vertical adjustable enables the camera to be shifted so as to take in the required field. In the front of the camera is fixed a lens of great light-gathering quality which produces an image of exceedingly clear detail. Inside the camera is a strip of gelatine film two and three-quarter inches wide, and usually about one hundred and sixty feet in length, which is wound upon a small pulley and drum. ”

“ Flat films are less bulky and less breakable than glass, and can be sent by post. They are supplied by the makers in packs of 12 for daylight loading into a film–pack adapter, which must be provided to take the place of the ordinary dark slides for glass plates. The lens should be a modern anastigmatic by a good maker. A focal length of about six inches will be best for a quarter–plate camera. A bad lens makes success impossible even by accident. ”

“ A thin, narrow ribbon of pictures 40 feet in length is a vastly different thing to handle from a rigid glass plate. Its flexibility presented many perplexing obstacles which had to be overcome. Those who used the old roll film with the snap-shot hand-camera of the early days, can relate pathetic and humorous stories of the trials and tribulations they suffered in passing the awkward length of film through the developing and other baths. When it was unwound from the roller preparatory to immersion in the developing solution, it persisted in buckling and twisting into strange contortions. ”

“ The preliminary operation is carried out with a machine, which stamps the holes by means of specially hardened steel punches. Extreme care has to be taken to carry out the task with mathematical accuracy, in order that the film may be used with any type of camera and projector. Without it steadiness of the picture upon the screen is absolutely impossible. ”

“ Every time current passes through the galvanometer, the light that is received from M, [6] passes through the aperture in the screen J, and is focussed by the lens N to a point upon the revolving film. As soon as the current ceases, the mirror swings back to its original position, and the film is again in darkness. Upon being developed a photograph, similar to the negative used for preparing the metal print is obtained. If desired the apparatus can be so arranged that the received picture is a positive instead of a negative. ”

“ Opening the side of the camera obviously ruins the whole of the unexposed film threaded through the mechanism, so that when picture taking is resumed the handle must be given a few more turns to make sure that the whole of the light-ruined film has passed through the gate. Seeing that one turn of the handle represents eight exposures, equivalent to 6 inches of film, it is a simple matter to estimate how many turns of the handle are necessary to clear the gate of spoiled film. ”

“ Fireproof films are probably one of the most important developments in the whole great motion-picture industry, for through these, schools, colleges, churches, lecture halls, and other public places not fitted with the fireproof box in which the motion-picture 174 operator works, can have the advantage of cinematography.
It was a difficult matter to find a non-inflammable film, for science has not yet discovered a base that can be made without cellulose, but the base we know to-day was treated so as to be non-explosive and practically non-inflammable. ”

“ A moving-picture machine is really a rapid-fire repeating camera provided with a lens allowing of a very quick exposure. Internal mechanism, operated by a hand-crank or electric motor, moves the unexposed film into position behind the lens and also opens and closes the shutter at just the proper moment. The same machinery feeds down a fresh section of the ribbon-like film into position and coils the exposed portion in a dark box, just as the film of a kodak is rolled off one spool and, after exposure, is wound up on another. ”

“ On the main shaft is also arranged the shutter, E, which rotates [509] with the film-moving mechanism. Fig. 2 shows the simplicity of the camera. On the upper end of the box is the sensitized ribbon, which passes downward between guides before the lens opening. The bent ends of the cam operating bar, which give the fork, D, its reciprocating motion, are shown in Fig. 3. Fig. 4 is a general view of the instrument, showing the driving gear and film support. Fig. 5 shows the cinematograph camera in operation. It will be seen that the camera is very portable. ”

“ In appearance it is somewhat different; indeed, it is in two parts, the one containing the lighting arrangements and condensing lens, and the other embracing the mechanism and objective lens. The "taking" camera must have its parts enclosed in a light-tight box, because of the undeveloped, sensitized film, but the projecting kinetoscope, using only a fully developed positive film, may, and, for purposes of convenient operation, must be accessibly open. The illustration (Fig. 2) will show the projecting apparatus as used in practice. ”

“ But until we get perfection with machinery, that gives absolute correctness in the perforating of the film, a camera which is made to take such film, and the same mechanism, all made from the perfect model, with a shutter adjusted to the requirements of the picture, we shall have to put up with the flicker, or reduce it to a minimum, using the material we have at hand. It is surprising what individual operators use for the shutter, each swearing by his own idea, as though it were of any consequence what material is used so that it is opaque. ”

“ In loading, care must be taken that the sensitised surface is brought towards the lens, and that the object is not taken through the thickness of the celluloid base. In order to thread the film through the gate the focussing tube is pushed back slightly—it is made telescopic for the purpose—the spring catch of the gate is released, and the moving part swung back. The film is now slipped into the gate, care being taken to see that the hooks of the device whereby it is intermittently pulled down after each exposure engage with the perforations. ”

“ The "Alpha," which [23] costs a little more, is full value for money, and is well worth the slightly increased price. This camera is fitted with a light-proof hinged front panel giving access to the adjustable shutter, which permits the opening of the latter to be varied within wide limits and thus enables extremely rapid movements to be photographed while running the machine at the normal speed. The spool boxes carry 100 feet of film of standard gauge in each instance, and for general all-round work, such as the recording of topical events, either model will be found perfectly efficient. ”

“ It all depends on the light. The best flash-light powder gives a flash about one ten-thousandth of a second in duration, but that is by no means the speed limit of the film. The only trouble is enough light and sufficient shutter speed. Pictures have been taken by means of spark photography with an exposure of less than one three-millionth of a second. The whole secret of this machine lies in the shutter. This big disc with the slots in the edge is set up before the lens and run at such a speed that half a million slots per second pass before the lens. ”

“ To lighten the camera burden, and to simplify the various photographic processes, were the problems that confronted the American inventor. The first step toward film photography—and it was film photography that relegated camera bulk to the scrap heap—was a roll film made of coated paper to which a sensitive emulsion was applied, but the real goal was reached when cellulose was substituted as a film base. This made practicable the present flexible, transparent film with its attendant convenience and dependability. ”

“ The camera can make up to a hundred exposures per second, in which time twenty-two feet of film will have passed before the lens.
The film is so heavy that were it arrested bodily during each exposure and then jerked forward again, it might be injured. The mechanism of the mutograph, driven at regular speed, by an electric motor, has been so arranged as to halt only that part of the film which is being exposed, the rest moving forward continuously. ”

“ This receiver is capable of working at a fairly high speed, as the inertia of the moving parts is practically negligible; the weight of the arm and mirror being less than 20 grains. The hole in the screen is made slightly less in diameter than the traverse of the revolving cylinder, the slight distance between the cylinder and the screen allowing the light to disperse sufficiently to produce a line on the film of about the right thickness. ”

“ When the machine is running smoothly this tube I is in a horizontal position making the electrical connection at either end, but when the flap D rises, owing to the enlargement of the loop E in the film, the weight of mercury is thrown to one end of the tube, causing it to cant in such a way as to retain the flap D in a vertical position. If the film should take fire, only the picture before the lens is consumed. Even the perforated edges remain untouched, so that the film is not severed, and can continue its travel through the machine when the breakdown is repaired. ”

“ From this it went over a roller, and the cog wheel, which engaged in the perforations, thence down by means of the "gate," behind the lens and shutter. There two claws reached up and grasped the film as the motor operated, pulling down three-quarters of an inch each time, to be exposed as the shutter was automatically opened in front of the lens. ”

“ At times, under certain conditions, a two-bladed shutter is used also.
A reel of film may vary in length for a short [14] subject of fifty feet (or even less) , to a very long “feature” of a mile or so in length. In width, the strip of celluloid measures one and three-eighths inches. Between the two rows of perforations that engage with the teeth on the sprocket-wheels and by which a certain part of the intermittent mechanism pulls the film along, are little rectangular panels, already alluded to, containing the photographs. ”