Abstract

A new resolving power test chart has been made that embodies the features outlined by Dr. Gardner in an earlier report. A contact print of this chart is made with the aid of a small distant light source and a specially shaped diaphragm moving over the chart at constant speed. The final test chart has a continuous variation in contrast from one end of the target line to the other. This chart is to be used to determine the variation of resolving power with contrast for a given lens with a single exposure. The long lines of the target make it especially suitable for microphotometric examination of the final test images, thus bringing closer an objective method of determining the resolving power of a photographic lens.

© 1951 Optical Society of America

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References

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  1. I. C. Gardner, J. Opt. Soc. Am. 40, 257 (1950).
  2. P. W. Cobb and F. K. Moss, J. Franklin Inst. 205, 831 (1928).
    [Crossref]
  3. I. C. Gardner and F. A. Case, J. Research Natl. Bur. Standards 18, 449 (1937).
    [Crossref]
  4. C. W. Kendall and B. A. Schumacher, Photo. Tech. 3, Apr. (1941).

1950 (1)

I. C. Gardner, J. Opt. Soc. Am. 40, 257 (1950).

1941 (1)

C. W. Kendall and B. A. Schumacher, Photo. Tech. 3, Apr. (1941).

1937 (1)

I. C. Gardner and F. A. Case, J. Research Natl. Bur. Standards 18, 449 (1937).
[Crossref]

1928 (1)

P. W. Cobb and F. K. Moss, J. Franklin Inst. 205, 831 (1928).
[Crossref]

Case, F. A.

I. C. Gardner and F. A. Case, J. Research Natl. Bur. Standards 18, 449 (1937).
[Crossref]

Cobb, P. W.

P. W. Cobb and F. K. Moss, J. Franklin Inst. 205, 831 (1928).
[Crossref]

Gardner, I. C.

I. C. Gardner, J. Opt. Soc. Am. 40, 257 (1950).

I. C. Gardner and F. A. Case, J. Research Natl. Bur. Standards 18, 449 (1937).
[Crossref]

Kendall, C. W.

C. W. Kendall and B. A. Schumacher, Photo. Tech. 3, Apr. (1941).

Moss, F. K.

P. W. Cobb and F. K. Moss, J. Franklin Inst. 205, 831 (1928).
[Crossref]

Schumacher, B. A.

C. W. Kendall and B. A. Schumacher, Photo. Tech. 3, Apr. (1941).

J. Franklin Inst. (1)

P. W. Cobb and F. K. Moss, J. Franklin Inst. 205, 831 (1928).
[Crossref]

J. Opt. Soc. Am. (1)

I. C. Gardner, J. Opt. Soc. Am. 40, 257 (1950).

J. Research Natl. Bur. Standards (1)

I. C. Gardner and F. A. Case, J. Research Natl. Bur. Standards 18, 449 (1937).
[Crossref]

Photo. Tech. (1)

C. W. Kendall and B. A. Schumacher, Photo. Tech. 3, Apr. (1941).

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Figures (6)

Fig. 1
Fig. 1

Master high contrast test chart. The line frequency is a linear function of the distance measured across the line. The zero of the chart is at the inner edge of the first broad dark line. The range of this chart is from 0.2 to 2.0 lines/mm.

Fig. 2
Fig. 2

Line frequency as a linear function of distance as obtained from the finished chart. The average departure from linearity does not exceed 1 percent, and the maximum departure for any point does not exceed 2 percent.

Fig. 3
Fig. 3

Master high contrast 3-line test chart. The line frequency varies in steps equal to 2 6 from one group to the next. The range of frequency for this chart is from 0.2 to 3.2 lines/mm.

Fig. 4
Fig. 4

Apparatus used in making the variable contrast master test chart from the master high contrast test chart.

Fig. 5
Fig. 5

Variable contrast master test chart. In addition to the features contained in the master high contrast test chart, the contrast varies in a linear manner from 0 to 1.5. The “moiré” effect appearing in the right-hand portion of the illustration is produced by the interaction of the periodic pattern of the half-tone screen and the pattern of continuously varying line spacings in the chart. Consequently, the above figure is not a true reproduction of the chart, although it is a fairly close approximation in the left-hand portion.

Fig. 6
Fig. 6

The variation in contrast for increasing line frequency in the image for pan process emulsion. Target contrast is 1.3 for curve 1; 0.5 for curve 2; and 0.2 for curve 3. (The average density of the negative 0.45.)

Tables (1)

Tables Icon

Table I Resolving power in lines per millimeter for image contrast of 0.1 for three emulsions for three target contrasts.