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.
New Products
Further information concerning the material described below can be obtained by writing direct to the manufacturers. As in the case of technical papers, publication of these news items does not constitute endorsement of the manufacturer's statements nor of his products.
Tele-Spot Meter
The Tele-Spot Meter, supplied by Photo Research Corporation, 15024 Devonshire Street, San Fernando, California, is a sensitive and accurate photoelectric light-measuring device, which has an optical system enabling it to measure the light coming from a small area, or a narrow angle, such as a one-inch circle at ten feet.
On the front of the case is the objective, and on the rear side are the electric controls, view finder, and the footlambert meter. In use, it is aimed at the area or object to be measured, which is clearly seen in the view finder. When it is aimed correctly, a reading is taken, the mirror behind the lens swinging up to let the light fall on the sensitive photocell. The scale then indicates the brightness in footlamberts. A supplementary switch makes available several ranges on the meter. Such an instrument may be used to measure the range of brightness and distribution of illumination in a scene.
For the measurement of visual brightness, a filter is provided which matches the color sensitivity of the cell to the sensitivity of the human eye. For the measurement of photographic values, a different filter converts the cell sensitivity to that of panchromatic film.
Several types of Tele-Spot Meters are in production. One is for operation on alternating current only; another, extremely portable, is designed for battery operation.
T-Stop Calibration Service
One of the specialized services rendered by the same corporation is the photoelectric recalibration of lens apertures in terms of T stops.
A few years ago, some of the major film studios in Hollywood began to recalibrate their lenses in terms of actual light transmission instead of the theoretical /-stop values, because of the increasing accuracy demanded by color. Finally, this procedure has been given official standing by the recommendation of the National Bureau of Standards that lenses be marked in what it calls "T'-stop" values, instead of the older / scale.
When a lens is recalibrated by the corporation, new marks are placed on the scale which represent true transmission values. The stop marked T-4, for example, transmits exactly the amount of light that would be transmitted by a theoretically perfect //4 lens, in which there was no light loss whatsoever and no inaccuracy of focal length or scale marking.
607