A Professional Through-the-Lens CdS Exposure Control System with Optical Data Input for Motion-Picture Cameras

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Publisher: SMPTE — White Plains, NY, USA
Doc Type: Journal Article
Content Type: Original Research
Abbreviated Title: J SMPTE
Volume: 79, No. 8, pp. 709–712
Abstract: A need for a precise TTL exposure measurement accompanied the development of color reversal film. This new exposure system does not electrically introduce film speed and exposure time data into the meter circuit, but instead the data input is achieved by two unique, counter-rotating precision neutral density discs which maintain the illumination level on the photoresistor at a defined reference value. This method allows the photoresistor to work at a predetermined operating point irrespective of exposure data settings and object illumination. A measuring field of about 30% of the filmed area was determined advantageous for the 16mm film. The light to be measured is diverted by a beamsplitter in the viewfinder's light path, where a relay lens projects the light onto the photoresistor. A galvanometer indicates the illumination level on the film. The reduced light during camera operation is electrically compensated by switching bridge-resistors. The power supply for the exposure meter is stabilized and derived from the camera battery. Illumination of the indicator scale is attained through a light collecting prism. This exposure system sets new standards in measuring accuracy with a wide variety of interchangeable lenses.
Publication Date: 1970-08-01
DOI: 10.5594/J00888
ISSN: Print: 0361-4573
Link: https://doi.org/10.5594/J00888
Author(s): Erich KaestnerArnold & Richter K.G., Tuerkenstrasse 89, 8 Munich 13, Germany.
Copyright: © 1970 Society of Motion Picture and Television Engineers, Inc.

Bibliographic Reference(s)

Re-evaluation of Factors Affecting Manual or Automatic Control of Camera Exposure [Active]
Kastner E. , “Gegenuberstellung der Lichtmessmoglichkeiten vor und hinter dem Aufnahmeobjektiv bei professionellen Filmaufnahmen,” Kinotechnik , 10 : 1961 . EXTERNAL
Automatic Exposure Controls for Cameras , ANSI PH2.15–1964. EXTERNAL
General Purpose Photographic Exposure Meters (Photoelectric Type) , ANSI PH2.12–1961. EXTERNAL
Speed of Reversal Color Films for Still-Photography, Method of Determining , ANSI PH2.21–1961. EXTERNAL
Lichtelektrische Belichtingmesser. DIN 19010–1969. EXTERNAL

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Erich Kaestner; A Professional Through-the-Lens CdS Exposure Control System with Optical Data Input for Motion-Picture Cameras, Journal of the SMPTE ( Volume: 79, Issue: 8, August 1970); SMPTE, 1970. Available at https://doi.org/10.5594/J00888

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Erich Kaestner; A Professional Through-the-Lens CdS Exposure Control System with Optical Data Input for Motion-Picture Cameras, Journal of the SMPTE ( Volume: 79, Issue: 8, August 1970); SMPTE, 1970. Available at https://doi.org/10.5594/J00888

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<span class="citation">Erich Kaestner; <cite>A Professional Through-the-Lens CdS Exposure Control System with Optical Data Input for Motion-Picture Cameras</cite>, Journal of the SMPTE ( Volume: 79, Issue: 8, August 1970); SMPTE, 1970. Available at <a href="https://doi.org/10.5594/J00888" target="_blank" rel="noopener">https://doi.org/10.5594/J00888</a></span>

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Erich Kaestner; <cite id="bib-10-5594-j00888">A Professional Through-the-Lens CdS Exposure Control System with Optical Data Input for Motion-Picture Cameras</cite>, Journal of the SMPTE ( Volume: 79, Issue: 8, August 1970); SMPTE, 1970
<span class="doi">10.5594/J00888</span>
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Referenced By

Progress Committee Report for 1970 [Active]