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Journal of the SMPTE ( Volume: 74, Issue: 2, February 1965)
[ACTIVE]

The G-Number: A Photometric Lens-Aperture Designation

Metadata

Publisher
SMPTE — White Plains, NY, USA
Doc Type
Journal Article
Content Type
Original Research
Volume
74, No. 2, pp. 99–101
Abstract
The photometric aperture or G-number is a more realistic and accurate measure of a lens opening than the relative geometric aperture or f-number. The G-number is the ratio of the field luminance to the focal-plane illuminance. It is a single-number measurable quantity which expresses the exposure effectiveness of a lens opening taking into account all lens and mounting variables. The G-number is easy to measure, explain, use and understand. It relates camera-film exposure to sensitometric exposure, simplifies exposure calculations and the engineering of automatic exposure controlled cameras. The lens efficiency is 1/G.
Publication Date
1965-02-01
DOI
10.5594/J09265
ISSN
Print: 0361-4573
Link
https://doi.org/10.5594/J09265
Author(s)
Allen StimsonApparatus and Optical Div., 400 Plymouth Ave. N., Eastman Kodak Co., Rochester, N.Y. 14650
Copyright
© 1965 Society of Motion Picture and Television Engineers, Inc.

Bibliographic Reference(s)

  • 1. American Standard, Method for Determining Aperture Calibration of Motion-Picture Lenses , PH22.90–1964. EXTERNAL
  • 10. Walsh , Photometry , Constable & Co., Ltd. , London , 1958 . EXTERNAL
  • 2. American Standard, Method for Determining Speed of Photographic Negative Materials (Monochrome, Continuous Tone), PH2.5–1960. EXTERNAL
  • 3. American Standard, General Purpose Photographic Exposure Meters (Photoelectric Type) , PH2.12–1961. EXTERNAL
  • 4. Stimson Allen , “Measuring and judging photographic exposure of color film,” Phot. Sci. Eng. , 4 : no. 4 , 203 , July-Aug. 1960 . EXTERNAL
  • 5. American Standard, Automatic Exposure Controls for Cameras, PH2.15- 1964 . EXTERNAL
  • 6. Stimson Allen , “An interpretation of current exposure meter technology,” Phot. Sci. Eng. , 6 : no. 1 , 1 , Jan.-Feb. 1962 . EXTERNAL
  • 7. Nelson C. N. , “Safety factors in camera exposures,” Phot. Sci. Eng. , 4 : no. 1 , 48 – 58 , Jan.-Feb. 1960 ; also Jour. SMPTE, 69: 479–483, July 1960. EXTERNAL
  • 8. American Standard, Method for Determining Speed of Color Reversal Film for Still Photography , PH2.21- 1961 . EXTERNAL
  • 9. Diserens Charles , Traité de Photographic, VI Optique , Imprimeur - Editeur, Gauthiers Villars , Paris , 1944 . EXTERNAL
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Allen Stimson; The G-Number: A Photometric Lens-Aperture Designation, Journal of the SMPTE ( Volume: 74, Issue: 2, February 1965); SMPTE, 1965. Available at https://doi.org/10.5594/J09265
Snippet:
Allen Stimson; The G-Number: A Photometric Lens-Aperture Designation, Journal of the SMPTE ( Volume: 74, Issue: 2, February 1965); SMPTE, 1965. Available at https://doi.org/10.5594/J09265

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Allen Stimson; The G-Number: A Photometric Lens-Aperture Designation, Journal of the SMPTE ( Volume: 74, Issue: 2, February 1965); SMPTE, 1965. Available at https://doi.org/10.5594/J09265
Snippet:
<span class="citation">Allen Stimson; <cite>The G-Number: A Photometric Lens-Aperture Designation</cite>, Journal of the SMPTE ( Volume: 74, Issue: 2, February 1965); SMPTE, 1965. Available at <a href="https://doi.org/10.5594/J09265" target="_blank" rel="noopener">https://doi.org/10.5594/J09265</a></span>

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Preview:
Allen Stimson; The G-Number: A Photometric Lens-Aperture Designation, Journal of the SMPTE ( Volume: 74, Issue: 2, February 1965); SMPTE, 1965
doi: 10.5594/J09265
url: https://doi.org/10.5594/J09265
Snippet:
<li>
Allen Stimson; <cite id="bib-10-5594-j09265">The G-Number: A Photometric Lens-Aperture Designation</cite>, Journal of the SMPTE ( Volume: 74, Issue: 2, February 1965); SMPTE, 1965
<span class="doi">10.5594/J09265</span>
</li>

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