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.
118 CINEMATOGRAPHIC ANNUAL x
sitometric strip is detached from the roll, the densities of the various deposits measured and its H and D curve plotted. From this curve the degree of development, gamma, is determined. This value gives a numerical expression of the degree of development. Figure IV shows an H and D curve which resulted from the exposure in a sensitometer of panchromatic negative film which was developed in a machine in one of the laboratories in Hollywood. The slope of the straight line portion of this curve gives the measure of the degree of development. This slope, as aforestated, is expressed mathematically as the tangent of the angle formed by the intersection of the straight line portion of the H and D curve with the log exposure axis.
Let us suppose now that we understand the procedure by which the degree of development may be ascertained and let us further assume that we want to check up on the degree of development on a definite emulsion number of film, in a stated developer, throughout a night's work. We shall furthermore assume that this development will be carried out in a developing machine. The procedure to be followed first necessitates the exposure of, let us say, a dozen sensitometric strips, all of which have had exactly the same exposure condition imposed upon them. At the beginning of the night's work and attached to the first roll going through the machine is one of these sensitometric strips. At stated intervals, say every 5000 ft., another of these exposed strips will be sent through the machine. This procedure is carried out at 5000 ft. intervals for the complete night's run. At the end of the night's work all of the various sensitometric strips, properly labeled as to the period during the night they were developed, are assembled, their densities read, and their curves plotted. From each strip gamma is determined and it is then possible to make a study of gamma in comparison with the film footage put through the developer. This procedure carried out for several nights and for several different mixtures of the same type of developer, leads to a rather conclusive figure as to the degree of contrast (gamma) that is being obtained for picture negatives.
It might be interesting to state at this point that a survey of the various laboratories in and around Hollywood leads to the conclusion that the average picture gamma arrived at is in the neighborhood of 0.68. This, of course, is the average of all laboratories. It is, furthermore, interesting to note that the departure from this average is not great. There is one unit which works at a somewhat lower gamma than the average, their gamma being approximately 0.55. There is another unit producing a somewhat more contrasty negative than the average and it is found that this unit works at a gamma value of approximately 0.80. Of course, considering the magnitude of difference between the low and the high values as stated, it would seem that there is an appreciable difference in the type of negative generally produced. However, inasmuch as the negative development in ten laboratories was studied and the average of all was 0.68, it means that many of them must be producing negatives relatively close to this mean value. These differences in