Abstract

A new non-intermittent sensitometer has been constructed which consists of two sector wheels rotating about the same axis at different angular speeds. During the exposure, the larger disk makes only one revolution. In this interval, the small disk makes many revolutions but the large wheel covers the photographic material except for one revolution of the small wheel.

With the ordinary sector wheel sensitometer, the exposure range is rarely more than 256 to 1 because of the difficulty of cutting the wheel. It is shown that by using two sector wheels, the exposure range may easily be increased to 16,384 to 1. An extension of this principle to three disks would not involve any serious mechanical difficulties and would increase the exposure range to more than one million to one.

© 1925 Optical Society of America

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References

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  1. W. de W Abney: Phot. Jour. 18, p. 56; 1893.
  2. L. A. Jones: Frank. Inst. J. 189, pp. 303-329; March, 1920.
    [CrossRef]
  3. K. Schwarzschild: Phot. Corr. p. 171; 1899.
  4. L. A. Jones: J.O.S.A. & R.S.I.,  7, pp. 305-309; April, 1923.
    [CrossRef]
  5. Sheppard and Mees: “Investigations on the Theory of the Photographic Process” (Longmans, Green and Co.1907).

1923 (1)

L. A. Jones: J.O.S.A. & R.S.I.,  7, pp. 305-309; April, 1923.
[CrossRef]

1920 (1)

L. A. Jones: Frank. Inst. J. 189, pp. 303-329; March, 1920.
[CrossRef]

1899 (1)

K. Schwarzschild: Phot. Corr. p. 171; 1899.

1893 (1)

W. de W Abney: Phot. Jour. 18, p. 56; 1893.

Abney, W. de W

W. de W Abney: Phot. Jour. 18, p. 56; 1893.

Jones, L. A.

L. A. Jones: J.O.S.A. & R.S.I.,  7, pp. 305-309; April, 1923.
[CrossRef]

L. A. Jones: Frank. Inst. J. 189, pp. 303-329; March, 1920.
[CrossRef]

Mees,

Sheppard and Mees: “Investigations on the Theory of the Photographic Process” (Longmans, Green and Co.1907).

Schwarzschild, K.

K. Schwarzschild: Phot. Corr. p. 171; 1899.

Sheppard,

Sheppard and Mees: “Investigations on the Theory of the Photographic Process” (Longmans, Green and Co.1907).

Frank. Inst. J. (1)

L. A. Jones: Frank. Inst. J. 189, pp. 303-329; March, 1920.
[CrossRef]

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

L. A. Jones: J.O.S.A. & R.S.I.,  7, pp. 305-309; April, 1923.
[CrossRef]

Phot. Corr. (1)

K. Schwarzschild: Phot. Corr. p. 171; 1899.

Phot. Jour. (1)

W. de W Abney: Phot. Jour. 18, p. 56; 1893.

Other (1)

Sheppard and Mees: “Investigations on the Theory of the Photographic Process” (Longmans, Green and Co.1907).

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Figures (3)

F. 1
F. 1

Drawing of the two sector wheels which rotate about the same axis but which are shown with their axes of rotation separated for the sake of simplicity. The position of the photographic material with respect to each wheel is indicated by the rectangle MNOP. The source of light lies behind the plane of the drawing on the perpendicular erected at the center of the rectangle.

F. 2
F. 2

Photograph of the shutter mechanism of the sensitometer. In this model, the large sector wheel contains five steps and the small sector wheel eight steps. The motor drives the small wheel at the rate of one revolution per second by means of the worm gear. The large wheel is driven by the small one through a train of bach gears which does not show in the photograph. The period of revolution of the large wheel is thirty-two seconds.

F. 3
F. 3

Photograph of the completed sensitometer showing the lamp house (M), the potentiometer (P), the sector wheels (S), the plate holder (H), and the plate holder slot (0). The lamp house is readily detachable so that other sources of light may be used at will.

Equations (9)

Equations on this page are rendered with MathJax. Learn more.

ϕ α = 2 n 1
n = log ( 2 ϕ / α ) log 2
m = log ( 2 θ / β ) log 2
θ = K α 2
m + n = log ( 2 K ϕ / β ) log 2
W R = 2 π θ K + W R K
W = ( 2 π θ ) R K 1
W = ( 2 π K α 2 ) R K 1
γ = W R + θ K W R K