Although a lens is the most important part of the photographer's
apparatus, it is not absolutely necessary for the production of
photographs. Very good pictures can be made by means of a pinhole.
Remove the lens from the camera, and insert in its place a sheet of
thin, hard cardboard. In the centre make a tiny hole with a
fine-pointed needle made red-hot. Another method is to make a large
hole in the cardboard, and paste over it a piece of tinfoil and make
the pinhole in this. The essential point is that the hole be perfectly
round without any burring at the edges. The most perfect arrangement
can be obtained by getting a watchmaker to drill a fine hole through a
piece of sheet metal. The diameter of the hole should not be greater
than one-fiftieth of an inch. Whatever is used, cardboard or metal, it
should be blackened all over to prevent the reflection of light in the
camera. The focusing glass should be brought within about 6 inches of
the hole. Owing to the small amount of light admitted, focusing is
very difficult. It can be done by pointing the camera towards the sun
and focusing its image. For the same reason the exposure is very long,
ranging from ten minutes to half an hour; it is, in fact, difficult to
overexpose.
[Illustration: Negative by F. C. Lambert. From Anthony's International
Annual, 1894. FIG. 68.--PINHOLE PHOTOGRAPHY.]
[Illustration: (Photograph made through a slit without a lens.) By
Roland Briant. FIG. 69.--THE WHITE ROBE OF NATURE.]
It is usually stated that no focusing is required, the larger the
plate the wider the angle, but according to Prof. Pickering, 12 inches
is the maximum distance for sharp work.
Peculiar diffused effects can be obtained by using a fine slit in
place of the pinhole. The picture shown on page 82 is an example.