The sciopticon manual : explaining Marcy's new magic lantern, and light, including magic lantern optics, experiments, photographing and coloring slides, etc. (1874)
Marcy, L. J., author · Philadelphia : L.J. Marcy · leaf 30
20 SCIOPTICON MANUAL. UNEQUAL ILLUMINATION. We can see that the brightness of an image decreases from the centre towards the margin. The diameter of the pencil g g passing through the lens parallel to its axis, is of the same size as the opening of the stop J5, and exceeds the diameter of the… … detracting from its distinctness. With a short exposure in the camera, this unequal illumination causes an under¬ exposure at the margin. In the Sciopticon it is even exaggerated by the reflector, but we generally wish the objects occupying the central portion of the 11 field of view” to stand out…
Lantern projection · Slides (Photography)
Internet Archive · Getty Research Institute · Public domain (published before 1931). Free to use for anything.
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