The advance of photography : its history and modern applications (1911)

Record Details:

Title:
The advance of photography : its history and modern applications
Date:
1911
Publisher:
London : K. Paul, Trench, Trübner & Co., Ltd.
Volume:
The advance of photography : its history and modern applications
Leaf #:
000169
Language:
English
Subjects:
Motion Pictures, Motion pictures--Technology
Collection:
Books
Format:
Books
Contributor:
Media History Digital Library
Sponsor:
Media History Digital Library
Coordinator:
Media History Digital Library
Description:
Date Added:
May 02, 2024
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CAMERA APPLIANCES 135 time at one's disposal. We refer to the pinhole camera. As is generally known, this instrument is so called, since the image formed on the plate is produced by light entering the dark chamber through a small circular hole, usually from -V" to TJo " in diameter. The formation of the image is illustrated in the accompanying diagram (53), and it will be readily recognized that the size of the image g' a' f bears the same relation to the size of the object g a / that the distance of the pinhole V from the screen (o a') does to the distance of the object from the pinhole. -r W -~ifm\ma Fig. 53. The distance o g' is much greater than the distance o a', and therefore while it is possible to obtain photographs with the same pinhole for very varying distances of screen from pinhole, yet, unless that distance is suitably chosen, the centre of the plate is likely to be over exposed when the edges have received the correct amount of exposure. Still, there is a fairly wide range over which practically uniformly good results may be obtained. Lord Rayleigh x has shown, as the result of theory and experiment combined, that for light from the most photoactive part of the spectrum the best results are to be obtained when d2/f=\0-5 x6". In this d=the diameter 1 See Phil. Mag., xxxi., pp. 87 et seq., 1891.