The science and practice of photography : an elementary textbook on the scientific theory and a laboratory manual (1920)
Roebuck, John R. (John Ransom), 1876-1965 · New York ; London : D. Appleton and company · leaf 45
GELATINE DRY PLATE 23 18. Photometer. — To measure the density of a photographic plate it is possible to separate the sil- ver from a measured area of a negative, and from this get the density. But this method is very tedious and on account of the very small quantities of silver, is not accurate.… … of equation 4 above. For this purpose Hurter and Driffield modified the ordinary bench photometer to make the apparatus pictured in the diagram. Fig. i. Outside of the box at each end is placed a lamp, and the central box can be moved toward either end, thus getting more light from one lamp and…
Photography
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