The fluctuations of light throughout the year and again throughout the day, are so great that no photographer could adequately allow for them with any certainty of a proper exposure. The best he could do was to make a more or less well-founded guess. It was clear that such a matter must be governed by a law of nature and with the object in view, therefore, of reducing exposure to a system we made up our minds to work together at the subject.

The Actinograph, 1880

The photographic researches of Ferdinand Hurter & Vero C. Driffield (Unknown Binding) by Ferdinand Hurter

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