Optic projection : principles, installation and use of the magic lantern, projection microscope, reflecting lantern, moving picture machine, fully illustrated with plates and with over 400 text-figures (1914)

Record Details:

Title:
Optic projection : principles, installation and use of the magic lantern, projection microscope, reflecting lantern, moving picture machine, fully illustrated with plates and with over 400 text-figures
Date:
1914
Author:
Gage, Simon Henry, 1851-1946
Publisher:
Ithaca, N.Y. : Comstock Publishing Co.
Volume:
Optic projection : principles, installation and use of the magic lantern, projection microscope, reflecting lantern, moving picture machine, fully illustrated with plates and with over 400 text-figures
Leaf #:
000245
Language:
English
Format:
Books
Contributor:
Gerstein - University of Toronto
Sponsor:
MSN
Coordinator:
Media History Digital Library
Description:
Bibliography: p. 693-703
Date Added:
July 19, 2022
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230 MICRO-PROJECTION WITH OCULARS [Cn. IX FIG. 127. HUYGENIAN OCULAR IN SECTION. (From The Microscope). F. L. Field lens. This aids the objective in forming a real image. D Diaphragm in the ocular. It is at this level that the real image is formed in ordinary microscopic observation. E. L. The eye lens. In projection this acts like an objective and projects upon the screen an image of the real image (see fig. 207). A xis The optic axis of the microscope. E. P. Eye-point or Ramsden's circle. § 357. Projection oculars. — Any ocular may be used for projection. The lower powers, x 2, X3, x 4, x 6, (§ 357a) are better than the higher powers, for they cut down the field less, there is less loss of light, and there is not an inordinate magnification. Concave lenses having a virtual focus are indicated by the minus sign ( — ) . If the dioptry of a lens is given, to find the principal focus: divide i meter by the dioptry. For example, the dioptry of the amplifiers mentioned above (§ 356) is — 5 for one and — 10 for the other. Their foci are then i meter, ~5 i meter. That is, they are concave lenses of 1/5 and i/io of a meter focus. -10 On the other hand, to find the dioptry of a lens whose principal focus is known, divide i meter by the principal focus and the result will represent the dioptry of the given lens. Taking the same case as before where the amplifiers have principal foci of 1/5 and i/io meter, As the lenses are known to be concave, the minus sign is placed before the dioptry: • — 5, — 10 diopters. The increase in magnification given by the amplifiers, — 5, — 10 was found to average 1.7 for the — 5 and 2.5 for the — 10. The average was obtained by considering all the screen distances and all the different objectives shown in the table, § 391. See also § 392a.