We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
80 PRINCIPLES OF CINEMATOGRAPHY
threaded through each rack by hand. To assist in this operation, the racks are made removable and supports, shown at *23\ Figure 33, are provided above the tanks on which to hang each rack while it is being threaded. The threading operation is, of course, somewhat difficult and it should only be necessary to re-thread a machine after it has been emptied for cleaning, etc. Once the machine is threaded with leader film provision must be made for attaching the leading edge of the first roll which is to be processed to the trailing edge of the leader film. Obviously, with the machine running at speeds over 30ft. (9 14-metres) per minute, a cemented join is out of the question. This is overcome by using a machine rather similar to a film splicer but which employs staples or rivets to secure the films together instead of the normal film cement.
Feed Rolls and Splicing Table
As will be seen from Figure 33 two feed roll holders, marked (1) and (2), are provided. This is necessary since a support must be provided for roll No. 2 while roll No. 1 is still passing through the machine. An alarm signal system is fitted and arranged to cause a buzzer to operate and so warn the man running the machine that either roll No. 1 or roll No. 2 is almost exhausted. This mechanism consists of an arm (3) which carries a stainless steel roller, mounted in ball bearings and recessed at its centre so that only the edges of the roller come into contact with the film. Attached to this arm is a mercury switch (4) which, when the roll has diminished in size sufficiently to allow arm (3) to bring it to a horizontal position, makes electrical contact and energizes a solenoid. This solenoid releases a pawl which falls by gravity and locks the toothed wheel connected to a sprocket wheel (8), thereby holding the film stationary. The mercury switch is in series with both the solenoid and an electrical buzzer so that, at the same instant, an alarm signal occurs to warn the operator that the roll of film is exhausted.
The splicing unit, shown in Figure 34, consists of a cast base supporting a channel 35-5-mm in width. Two spring loaded dies are mounted flush with the base of this channel and it is at this point that the two films to be joined are overlapped. The perforations of the two films must be lined up accurately, and an overlap of 3 perforations is necessary. The film channel is divided into two halves by the dies, and in the centre of each half is mounted a spring loaded film clamp. These clamps are closed onto the films after they have been lined up but before the splicing operation