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.
156 PRINCIPLES OF CINEMA TOGRAPHY
without altering the main resistance setting. With the diaphragm type of light change mechanism, or exposure regulating system, it is again possible to calibrate the size of the diaphragm openings into 21 steps and, therefore, to set the main resistance to give a good exposure to an average negative when the diaphragm is set to the middle or eleventh aperture size.
Aids to Selecting the Exposure Settings
There are three main courses open to the grader when selecting the correct exposure for any particular scene. These may be roughly described as follows: -(1) Inspection and selection by experience. (2) Selection by comparison with similar negatives for which the correct exposure is known. (3) By practical tests on instruments designed to make a series of exposures corresponding to the 21 settings available on the printer.
Whichever method is adopted, the exposure given by the grader is subject to correction after a trial print has received its first viewing at the studio. Unless the grader has had very considerable experience with the positive film used to make the prints, with the machines at his particular laboratory and with the type of photography practised by the cameraman who made the negatives, he may have considerable difficulty in estimating the correct exposure setting required to produce the most satisfactory prints from his negatives.
For these reasons it is now usual to find either one of the following methods used in present day laboratories. The first method is one of comparison and the machine used for this purpose is seen in Figure 67. This figure shows a plan view of the instrument which is seen to consist essentially of a rectangular box 'B', upon which are mounted a supply spool 'S\ holding the film which is to be graded, a take-up spool 'W', to accommodate the film after grading, and two sprocket wheels *F and "F, used to carry the film past an observation window 'N\ To the left of this window is mounted a large disc 'D' having 21 apertures cut in it, each exactly the size of one picture. Each aperture is numbered from one to twenty-one, and contains a sample negative which, by experience, was found to be correctly exposed at the light setting indicated by the number printed alongside the picture. An opal screen 'O' is mounted below the window 'N' and also below a second window 4M\ so that a light source within the box *B' illuminates both apertures.
In operation the film to be graded is moved forward until one frame of the first scene is correctly aligned with window *N',