Abstract

The resolving power of a photographic material may be defined qualitatively as the ability to show fine detail in the picture. It is defined numerically as the number of lines and spaces per millimeter which it resolves. This definition, however, is rather inadequate since resolving power depends on many factors, such as the ratio of the width of the line to the width of the space, the color temperature of the light image, or the wavelength where monochromatic radiation is in question, and the contrast in the object.

The present paper gives some results of an experimental investigation of the dependence of the resolving power upon the contrast in the test object, where contrast is defined as the ratio of the photographic intensities of two adjacent small images to be resolved.

The method of investigation was to photograph in a reducing camera a series of parallel line test objects differing only in contrast, and by microscopic exmaination of the developed photographic images to determine the maximum resolving power for the respective objects.

The results show that the resolution changes very rapidly with contrast at low contrast values. Thus, with no resolution at unit contrast, the resolving power reaches approximately 65% of its maximum value for a test object density of 0.5, that is, a transmission through the opaque spaces of 31.5% or a contrast of 3.17; and 87% of its maximum value when the test object density is 1.0, transmission 10% and contrast is 10. The maximum value of resolving power is reached when the test object has a contrast of approximately 100 to 200.

© 1928 Optical Society of America

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References

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  1. Otto Sandvik. On the Measurement of the Resolving Power of Photographic Materials, J.O.S.A. & R.S.I.,  14: p. 169; 1927.
    [Crossref]
  2. L. A. Jones. The Contrast of Photographic Printing Papers. J. Frank. Inst.,  202, p. 177, 1926;J. Frank. Inst. 203, p. 111, 1927.
    [Crossref]
  3. C. E. K. Mees. On the Resolving Power of the Photographic Plates. Proc. Roy. Soc.,  83A: p. 10; 1909.The Physics of the Photographic Process. J. Frank. Inst.,  179: p. 141, 1915.
    [Crossref]
  4. F. E. Ross. Photographic Sharpness and Resolving Power. Astro. Phys. J.,  52: p. 201; 1920.
    [Crossref]
  5. F. E. Ross. Ibid.

1927 (1)

Otto Sandvik. On the Measurement of the Resolving Power of Photographic Materials, J.O.S.A. & R.S.I.,  14: p. 169; 1927.
[Crossref]

1926 (1)

L. A. Jones. The Contrast of Photographic Printing Papers. J. Frank. Inst.,  202, p. 177, 1926;J. Frank. Inst. 203, p. 111, 1927.
[Crossref]

1920 (1)

F. E. Ross. Photographic Sharpness and Resolving Power. Astro. Phys. J.,  52: p. 201; 1920.
[Crossref]

1909 (1)

C. E. K. Mees. On the Resolving Power of the Photographic Plates. Proc. Roy. Soc.,  83A: p. 10; 1909.The Physics of the Photographic Process. J. Frank. Inst.,  179: p. 141, 1915.
[Crossref]

Jones, L. A.

L. A. Jones. The Contrast of Photographic Printing Papers. J. Frank. Inst.,  202, p. 177, 1926;J. Frank. Inst. 203, p. 111, 1927.
[Crossref]

Mees, C. E. K.

C. E. K. Mees. On the Resolving Power of the Photographic Plates. Proc. Roy. Soc.,  83A: p. 10; 1909.The Physics of the Photographic Process. J. Frank. Inst.,  179: p. 141, 1915.
[Crossref]

Ross, F. E.

F. E. Ross. Photographic Sharpness and Resolving Power. Astro. Phys. J.,  52: p. 201; 1920.
[Crossref]

F. E. Ross. Ibid.

Sandvik, Otto

Otto Sandvik. On the Measurement of the Resolving Power of Photographic Materials, J.O.S.A. & R.S.I.,  14: p. 169; 1927.
[Crossref]

Astro. Phys. J. (1)

F. E. Ross. Photographic Sharpness and Resolving Power. Astro. Phys. J.,  52: p. 201; 1920.
[Crossref]

Ibid. (1)

F. E. Ross. Ibid.

J. Frank. Inst. (1)

L. A. Jones. The Contrast of Photographic Printing Papers. J. Frank. Inst.,  202, p. 177, 1926;J. Frank. Inst. 203, p. 111, 1927.
[Crossref]

J.O.S.A. & R.S.I. (1)

Otto Sandvik. On the Measurement of the Resolving Power of Photographic Materials, J.O.S.A. & R.S.I.,  14: p. 169; 1927.
[Crossref]

Proc. Roy. Soc. (1)

C. E. K. Mees. On the Resolving Power of the Photographic Plates. Proc. Roy. Soc.,  83A: p. 10; 1909.The Physics of the Photographic Process. J. Frank. Inst.,  179: p. 141, 1915.
[Crossref]

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Figures (8)

F. 1
F. 1

Parallel line test object.

F. 2
F. 2

Curves showing the change of the resolving power with the time of exposure for an Eastman Process Plate. The time of development in minutes is indicated on each curve.

F. 3
F. 3

Curves showing the resolving power for developments to different values of gamma. The different values of gamma are given at the head of Table 1.

F. 4
F. 4

Sketch showing growth of density under the geometrical edge of the line element, E, with exposures for a given time of development.

F. 5
F. 5

Diagram showing the growth of density, with exposure at different distances from the geometrical edge.

F. 6
F. 6

The curve shows the dependence of resolving power on the density, D, of the opaque sections of the test object for an Eastman 33 emulsion. Where D=log C and C is the contrast of the test object.

F. 7
F. 7

Gives a comparison between the observed values of the relation between contrast and resolving power and the values of the relation computed from formula (5).

F. 8–11
F. 8–11

These curves show the dependence of the resolving power on contrast in the test for Eastman Process, Eastman 40, Eastman Speedway, and W. & W. Panchromatic Plates.

Tables (10)

Tables Icon

Table 1 The dependence of resolving power on the density, D, of the opaque sections of the test object where D=log C and C is the contrast of the test object. The mean values of resolving power for the four different values of gamma, are listed in the last column.

Tables Icon

Table 2 A comparison of the averages of the observed values of R in the last column of Table 1 and the corresponding values of R computed from formula (5).

Tables Icon

Table 3 The dependence of the resolving power on the density, D, of the opaque sections of the test object. Where D = log C and C is the contrast of the test object. The tables are for Eastman Process, Eastman 40, Eastman Speedway, and W & W Panchromatic plates respectively.

Tables Icon

Table 4 The dependence of the resolving power on the density, D, of the opaque sections of the test object. Where D=log C and C is the contrast of the test object. The tables are for Eastman Process, Eastman 40, Eastman Speedway, and W & W Panchromatic plates respectively.

Tables Icon

Table 5 The dependence of the resolving power on the density, D, of the opaque sections of the test object. Where D=log C and C is the contrast of the test object. The tables are for Eastman Process, Eastman 40, Eastman Speedway, and W & W Panchromatic plates respectively.

Tables Icon

Table 6 The dependence of the resolving power on the density, D, of the opaque sections of the test object. Where D = log C and C is the contrast of the test object. The tables are for Eastman Process, Eastman 40, Eastman Speedway, and W & W Panchromatic plates respectively.

Tables Icon

Table 7 A comparison of the averages of the observed values of R in the last column of Tables 3 to 6 and the corresponding values computed from formula (5).

Tables Icon

Table 8 A comparison of the averages of the observed values of R in the last column of Tables 3 to 6 and the corresponding values computed from formula (5).

Tables Icon

Table 9 A comparison of the averages of the observed values of R in the last column of Tables 3 to 6 and the corresponding values computed from formula (5).

Tables Icon

Table 10 A comparison of the averages of the observed values of R in the last column of Tables 3 to 6 and the corresponding values computed from formula (5).

Equations (9)

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R = 1 d 1 0.05 .
D = log T 2 / T 1 = log 1 / T .
D c = log 1 / T c
D 0 = log 1 / T 0
C = T c / T 0
( log 1 / T 0 ) / ( log 1 / T c ) = log C = D 0 D c .
log C = D 0 .
R = C ( 1 e α D )
R = C ( 1 e α D )