| In the years before the announcement of the first photographic processes in 1839, artists who wished to make a quick record of a scene with the correct prospective used either a Camera Obscura or a Camera Lucida.The original design of the camera lucida was published by William Hyde Wollaston (1766-1828) in 1807. Wollaston's design, shown at the right, used a four-sided glass prism with angles of 90°, 67.5°, 135° and 67.5°. The critical angle for total internal reflection for glass with an index of refraction of 1.50 is 41.8°. Thus, the first reflection of the ray coming from the object S, with its angle of incidence of 67.5°, is total. The second reflection also has an angle of incidence of 67.5°, permitting all of the light from S to travel to the eye. The light from the paper P can still pass through the prism to the eye, allowing the action of the pencil on the paper to be seen. A small peephole is placed just above the prism to force the eye to be located at the optimum viewing point. |
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The camera lucida at the left is in the collection of the
United States Military Academy at West Point, New York. It was clamped to
the top of a step-ladder to be photographed.
At the right is a camera lucida from Middlebury College in Vermont. REF: Thomas B. Greenslade, Jr., "Nineteenth Century Textbook Illustrations XLVIII: The Camera Lucida", Phys.Teach., 27, 48-49 (1989) |
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The camera lucida at the right is in the Millington-Barnard Collection at the University of Mississippi. In the second half of the 1850s Prof. Frederick Barnard
bought a good deal of apparatus from Lerebours et Secretan of Paris. This
example rather resembles the simpler camera lucida that L&S illustrates
in the 1853 catalogue. If so, it originally cost 35 francs, or about $7.
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This cased Camera Lucida is by Charles Chevalier of Paris, and is in the collection of Hobart and William Smith Colleges in Geneva, New York. |