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.
54
' 30
in
N ■ /
>■
/
£
/
vt
/
* W
. /
IU
/
a
/
•75 0
U»S ' ?
UMi
F/'g. 3. A typical Positive Curve.
LOG E F/g. 4. A typical Negative Curve.
developing time, but if it is, certain troubles immediately arise : (a) No standard of grading can be maintained ; (b) Inconsistent results are obtained ; (c) Developing is delayed whilst adjustments for a particular job are made, during which time a large number of other reels are held up ; (d) Variable
*oh
/
to
TIME
Fig. 5. Control of Negative Gamma by variation of Processing Time.
Fig. 6. A typical Time-Gamma Curve.
area sound track must be of a high contrast for best results, and must be absolutely consistent.
It is for these reasons that every endeavour is made to have a fixed positive developing time and a fixed positive contrast. The negatives should, therefore, be made to suit the positive conditions. Correction can be applied in duping by application of the time-gamma curves for the duping emulsions.
Yet another variable factor that must be kept in mind is the difference in overall gamma likely to result between a contact print from a 16mm. negative and an optical print from a 35mm. negative, as the contrast in optical printing is much greater than in contact printing.
DISCUSSION
Mr. W. Buckstone : Would it be worth while considering in making the picture, photographing in a high key ?
The Author : Yes, I think it would be better. We can get 'our tone range in a high key, still retaining the intensities in the lower scale. Another way of getting a light print with soft gradation is by getting a low positive gamma. The difficulty is that sound requires a high positive contrast.
Mr. H. E. Dance : In schools there are two reasons why light prints are demanded> Firstly, the schools have not much money. Secondly, the projector must be portable.
Mr. W. Buckstone : Have you an optical bench available for 16mm. yet ?
The Author : We have one under construction, but it is taking a little longer than we had anticipated. We also have under construction a direct wipe machine.