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.
SOUND REDUCTION PRINTING 333
film at this point, to be cut completely away unless attention has been given to this possibility by regular inspection and replacement.
Obviously, all stationary surfaces must be maintained with a scratch-free mirror surface if valuable 35-mm negatives are to be safeguarded. This observation, and the previous discussion on the probable sources of scratching applies equally well to all machines and particularly to those in which non-rotating surfaces are employed. Since it is easier to finish soft metals to a high polish it is usual to find such parts manufactured in brass which, after polishing, are coated with an exceptionally hard deposit such as some forms of chromium plating. Many people are of the opinion that chromium plating of itself imparts a high polish to a metal surface this is quite inaccurate and, unless the base metal has been previously worked to a finish equal to that required after the plating operation, it will be found that small scratches or abrasions which were not removed not only remain present but are, in fact, greatly accentuated. This is an unavoidable occurence with electro-deposition due to crystal growth at the edges of a surface and can only be eliminated by careful workmanship before the plating is applied.
Although the foregoing observations may be thought to indicate the use of stainless steel at all such vital points it has been found that, once a mirror surface has been obtained on soft metal and repeated in the plated deposit, the resultant hardness and resistance to scratching can be higher than obtained with stainless steel.
Printer Illumination
In common with most other printing operations, the sound reduction printer requires a steady source of illumination. Obviously, any variation in exposure will reduce the quality of the final sound reproduction although the nature of the defect may cause other stages in the process to be suspected rather than the light source. For example, small increases in lamp brightness above the selected intensity may so badly over-expose the print that the high frequencies are 'filled in' and, since this would occur at the frequency of the lamp current variations, would result in the periodic loss of high response and consequent introduction of a low frequency. A similar effect is produced when exposure variations tend towards low intensities when, once more, the high frequencies are the first to be noticably affected and are periodically lost at a frequency equal to that of the lamp current variations. In all cases it is advisable to operate the printing lamp from a