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Sensitometry of photographic papers

1939; Elsevier BV; Volume: 228; Issue: 4 Linguagem: Inglês

10.1016/s0016-0032(39)90142-0

1879-2693

Loyd A. Jones, Carole A. Morrison,

3D Surveying and Cultural Heritage

The fundamental principles and methods of the sensitometry of photographic papers established by Jones, Nutting, and Mees in 1914 are reviewed. The necessity for the use of intensity scale exposure rather than the older time scale methods is shown.An account of the evolution of the design of an optical wedge sensitometer to fulfill the required sensitometric specifications leads to the description of a new instrument used in this study of the sensitometric characteristics of photographic papers. Details of the complete sensitometric process are given. The resultant characteristic curves from the different types and grades of papers are described and interpreted. The typical characteristic curve of modern papers is discussed and a revised method of determining numerical values, which describe the curve for practical purposes, is given. The new interpretation of the shape of the shoulder region of the curve is significant with respect to the quality of tone reproduction. The new group of characteristic values—speed, maximum gradient, exposure scale, maximum density, and contrast—is defined and discussed. Numerical values obtained by the new sensitometric method are given in tabular form for most of the current types and grades of photographic papers.