Journal of the Society of Motion Picture Engineers ( Volume: 51, Issue: 3, September 1948)
[ACTIVE]
Errors in Calibration of the f Number
Metadata
- Publisher
- SMPTE — White Plains, NY, USA
- Doc Type
- Journal Article
- Content Type
- Original Research
- Abbreviated Title
- J SMPE
- Volume
- 51, No. 3, pp. 242–260
- Abstract
- The present system of marking the diaphragm stops in terms of the geometric f number is subject to serious deficiencies so far as uniform performance for lenses set at the same marked stop opening is concerned. Decisions regarding the proper exposure time to use at a selected stop opening may be in error by ± 10 per cent for a lens whose surfaces do not have antireflection coatings, and by even greater amounts for a lens whose surfaces do have antireflection coatings. These errors arise from differences in the reflection and absorption losses in the lens elements themselves, departures of the measured from the nominal focal length, and departures of the measured diaphragm openings from the nominal diaphragm openings. A method is described whereby a lens can be calibrated by a light meter in terms of an ideal lens so that the variation in axial illumination in the focal plane need not exceed ± 2 per cent in using different lenses set to the same calibrated stop opening.
- Publication Date
- 1948-09-01
- DOI
10.5594/J11752- ISSN
- Print:
0097-5834 - Link
- https://doi.org/10.5594/J11752
- Author(s)
- Francis E. WasherNational Bureau of Standards, Washington, D. C.
- Copyright
- © 1948 Society of Motion Picture and Television Engineers, Inc.
Bibliographic Reference(s)
- Stop Calibration of Photographic Objectives [Active]
- Twentieth Century Camera and Accessories [Active]
- A Lens Calibrating System [Active]
- A System of Lens Stop Calibration by Transmission [Active]
- The Photometric Calibration of Lens Apertures [Active]
- Compensation of the Aperture Ratio Markings of a Photographic Lens for Absorption, Reflection, and Vignetting Losses [Active]
- An Instrument for Photometric Calibration of Lens Iris Scales [Active]
- A Simplified Method for Precision Calibration of Effective f Stops [Active]
- 11. Clarke D. B. Laube G. , “Method and Means for Rating the Light Speed of Lenses,” United States Patent No. 2,334,906, issued November 23, 1943 , and assigned to Twentieth Century-Fox Film Corporation. EXTERNAL
- 4. Sachtleben L. T. , “Method of Calibrating Lenses,” United States Patent No. 2,419,421, issued April 22, 1947 , and assigned to Radio Corporation of America. EXTERNAL
- 8. McRae D. B. , “Measurement of transmission and contrast in optical instruments,” J. Opt. Soc. Amer. , vol. 33 , p. 229 ; April, 1943 . EXTERNAL
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Francis E. Washer; Errors in Calibration of the f Number, Journal of the Society of Motion Picture Engineers ( Volume: 51, Issue: 3, September 1948); SMPTE, 1948. Available at https://doi.org/10.5594/J11752
Snippet:
Francis E. Washer; Errors in Calibration of the f Number, Journal of the Society of Motion Picture Engineers ( Volume: 51, Issue: 3, September 1948); SMPTE, 1948. Available at https://doi.org/10.5594/J11752
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Francis E. Washer; Errors in Calibration of the f Number, Journal of the Society of Motion Picture Engineers ( Volume: 51, Issue: 3, September 1948); SMPTE, 1948. Available at https://doi.org/10.5594/J11752
Snippet:
<span class="citation">Francis E. Washer; <cite>Errors in Calibration of the f Number</cite>, Journal of the Society of Motion Picture Engineers ( Volume: 51, Issue: 3, September 1948); SMPTE, 1948. Available at <a href="https://doi.org/10.5594/J11752" target="_blank" rel="noopener">https://doi.org/10.5594/J11752</a></span>
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Francis E. Washer; Errors in Calibration of the f Number, Journal of the Society of Motion Picture Engineers ( Volume: 51, Issue: 3, September 1948); SMPTE, 1948
doi: 10.5594/J11752
url: https://doi.org/10.5594/J11752
doi: 10.5594/J11752
url: https://doi.org/10.5594/J11752
Snippet:
<li> Francis E. Washer; <cite id="bib-10-5594-j11752">Errors in Calibration of the f Number</cite>, Journal of the Society of Motion Picture Engineers ( Volume: 51, Issue: 3, September 1948); SMPTE, 1948 <span class="doi">10.5594/J11752</span> </li>
Referenced By
- Standards and Recommended Practices [Active]
- Report of Lens-Calibration Subcommittee [Active]