The sciopticon manual, explaining lantern projection in general, and the sciopticon apparatus in paricular (1877)

Record Details:

Title:
The sciopticon manual, explaining lantern projection in general, and the sciopticon apparatus in paricular
Date:
1877
Publisher:
Philadelphia, J. A. Moore
Volume:
The sciopticon manual, explaining lantern projection in general, and the sciopticon apparatus in paricular
Leaf #:
00033
Language:
English
Collection:
Books
Format:
Books
Contributor:
University of California Libraries
Sponsor:
MSN
Coordinator:
Media History Digital Library
Description:
Date Added:
July 19, 2022
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24 SCIOPTICON MANUAL. CHAPTER III. THE CONSTRUCTION OF THE SCIOPTICON. THE PORTRAIT OBJECTIVE. —This objective (Fig. 13 or 15) is made for the camera, and is known mostly in its relations to photography. An objective, however, that with large opening, will give proper direction to rays from a large object to a small image in the camera, will answer equally well in giving direction to rays from the small picture in the Sciopticon back to life-size on a screen; both object and image being in the conjugate foci in either case. THE PLAIN LANTERN OBJECTIVE. —This objective, like the achromatic portrait objective (Fig. 13 or 15), has the advantage of a front and a back lens, A B (Fig. 14), so far apart that the tube serves as a stop for marginal rays with comparatively small loss of light. The front lens A is a meniscus of crown-glass, whose tube slides into a larger tube which holds the plano-convex crown- glass lens B. Arranged as in the diagram, the effect is scarcely inferior, so far as common observation goes, to that of the most expensive combinations. With the front tube reversed, so as to bring A near to B, the image is larger but less distinct. With only one lens the image is smaller. These different arrangements give the three powers commonly attributed to lenses mounted in this form. NO LOSS OF LIGHT FROM USING AN OBJECTIVE OF LOW POWER WITH A CONCENTRATED LIGHT. Were the picture p (Fig. 14) made luminous by light shining upon it, as in an opaque lantern, the light would radiate in all directions, and in accordance with the law