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.

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.






The camera lucida to 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.








By Thomas B. Greenslade, Jr.