RIBBON PHOTOGRAPHY—A NEW CAMERA.
The main shaft may be operated by a crank on the outside of the box, by hand or by any suitable motor. The sensitized celluloid perforated ribbon film maybe noticed passing downwards near the front end of the camera, in front of the exposure tension plate, the square aperture in which is exactly in line with the front aperture in the box. From this point the film, after exposure, passes downward between the sprocket wheel and pressure roller to the winding reel in the rear end of the camera, which is rotated by belt-connection to a pulley on the upper shaft and takes up the film ribbon as rapidly as it is exposed. A feed roll for the supply of unexposed film is not shown, but may be located at the rear of the camera, over the winding reel. The operation will be readily understood. The camera is placed upon the tripod or stand; the crank on the outside is rotated, which causes the film to travel downwards continuously, at exactly the same speed at which the lenses rotate, so that at every fraction of a second that it takes for each lens to pass behind the camera aperture an impression of light is made on the downwardly moving film; and as the lenses and film both move in unison, it follows that a sharp picture will be the result while the brilliancy of the illumination is at its maximum. The camera can be carried about as readily as any other camera. In practice it is found that the motion of the hand-operated crank is sufficiently uniform to permit of the proper reproduction of motion by the positive pictures projected upon the screen.
RIBBON PHOTOGRAPHY—EXPOSING AND PRINTING APPARATUS.
Our next [engraving] shows how the positive ribbon pictures for the vitascope and other forms of apparatus are printed; this is also the invention of Mr. Jenkins. It consists of reels supported on suitable upright standards holding respectively the sensitized ribbon film and the negative film. The film from the negative supply wheel is carried along over the sensitized film wheel, and both pass in contact, in continuous motion, under an exposing chamber illuminated by any source of white light, as an incandescent lamp or a Welsbach incandescent gaslight, thence over the toothed sprocket driving wheel to the winding wheels, the exposed film being wound first. This will be better understood by reference to our detailed [diagram] of the mechanism. It will be noticed that the reels are interchangeable, and hence, to make duplicate copies it is only necessary to remove the negative spool from the winding-up end to the supply-spool standard of the apparatus, and begin over again. The perforations in the edges of the film are of a special square shape, and give the square sprocket wheel of the propelling pulley a better tension on the film. The teeth pass through the perforations of both films, causing both to move at exactly the same time, and at all times to keep in perfect registry. The speed of the film passing under the exposing chamber must be absolutely uniform; this is obtained by propelling the sprocket wheel by an electric motor or by a spring motor. The electric motor is seen in the large [wood cut]. The axle of the motor has worm gear operating a cog wheel on the main shaft. The V-shaped elastic band holds the frame in which is a ground glass in contact with the film, producing a kind of tension on the film. To the left of the light chamber is a supplementary tension adjusted by screw nuts, as shown. Referring to the [diagram], two slotted diaphragm cards will be seen. These are placed over the ground glass just mentioned, at the bottom of the light chamber, and are for the purpose of regulating the amount of light that acts on the negative. If the negative film, as a whole, should be thin, then a card with a narrow slot is used, which allows a short exposure to be made if the negative and film are passed under it. If the negative is full of density, then the narrow card is removed, and the wider slotted card substituted, which allows a larger volume of light to act upon the negative film. The exposed film is wound around large open reels from a spool and is developed by passing through cloths of developer solution. The novelty in the device which we illustrate consists in the fact that the film moves continuously under a uniform source of light, under any intermittent motion or the use of shutters. The operation of exposing the film is carried out in a room illuminated by the usual ruby light.
RIBBON PHOTOGRAPHY—DIAGRAM OF THE PRINTING DEVICE.