The G-Number: A Photometric Lens-Aperture Designation

Metadata

Publisher: SMPTE
Doc Type: Journal Article
Article Type: research-article
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
Link: https://doi.org/10.5594/J09265
Author(s): Allen Stimson

Source Data (JSON)

Full registry record with provenance metadata. Open directly: /api/doc/10.5594-J09265.json

Reference this Doc

Plain text (ISO 690 compliant)

Preview:

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

HTML (ISO 690 compliant)

Preview:

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>

SMPTE's HTML Pub

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>