Abstract

An experimental study of the photography, from the ground, of objects in the upper atmosphere shows that the results are improved by the use of long-focal-length lenses, high contrast film, and color filters chosen with regard to the relative spectral qualities of the object and the sky background. The most difficult problem was the photography of dark gray objects against a blue sky, and for these conditions a blue filter gave best results. For these same conditions, an increase in vertical range (altitude) was found to give a greater decrease in subject contrast than an equal increase in horizontal range. Of lesser difficulty was the photography of bright, white objects against a blue sky; and for these conditions a red filter gave best results. Data were obtained regarding the optimum spectral-reflectance characteristics of targets for special purposes. The required characteristics of the photographic emulsion were the subject of a detailed study. A high contrast, high speed panchromatic film, especially designed for this work, is described. Exposure and processing data for this film are given.

© 1950 Optical Society of America

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References

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  1. S. Q. Duntley, J. Opt. Soc. Am. 38, 179 (1948).
    [Crossref]
  2. S. Q. Duntley, J. Opt. Soc. Am. 38, 237 (1948).
    [Crossref] [PubMed]
  3. H. S. Coleman, F. J. Morris, H. E. Rosenberger, and M. J. Walker, J. Opt. Soc. Am. 39, 515 (1949).
    [Crossref]
  4. H. S. Coleman and H. E. Rosenberger, J. Opt. Soc. Am. 39, 990 (1949).
    [Crossref]

1949 (2)

1948 (2)

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Figures (8)

Fig. 1
Fig. 1

Relative quality of the photographic images of shellbursts shown as a function of altitude and horizontal range. This shows the great dependence of image quality on altitude and relatively small dependence on horizontal range.

Fig. 2
Fig. 2

Relative visibility of photographic images of various cloth targets: A, white; B, yellow; C, red; D, improved yellow; E, black. A blue filter was used over the camera lens in each case

Fig. 3
Fig. 3

Spectral-reflectance curve for two yellow targets. Curve A, poor yellow target; Curve B, improved yellow target.

Fig. 4
Fig. 4

Density-versus-log-exposure curves for typical negative motion-picture films used in the early stages of these tests.

Fig. 5
Fig. 5

D-logE curves for Kodak Linagraph Shellburst Film.

Fig. 6
Fig. 6

A filter is chosen which isolates the spectral region where the contrast of the subject is the greatest, and a film is chosen which gives enhanced image contrast.

Fig. 7
Fig. 7

Spectral-sensitivity curve for Kodak Linagraph Shellburst Film.

Fig. 8
Fig. 8

Graph showing the difference between ordinary landscape photography, where the camera image often occupies a large interval such as “a” to “b” on the D-logE curve of the film, and aerial target photography, where the image usually occupies a short interval such as “d” to “e.” Because of the large difference in the luminance scale of these subjects, the exposure for the sky area differs by approximately ten times in the two cases, even though the two films have the same sensitivity as measured in the toe region of the curve.

Tables (7)

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Table I Filters used in the tests.

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Table II Data showing the different effects of horizontal and vertical range.

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Table III Effect of change in gamma and spectral region.

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Table IV Exposure data.

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Table V Filter factors.

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Table VI Kodak D-11 Developer.

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Table VII Recommended development times in D-11.

Equations (1)

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t = 1.25 f 2 / B × R ,