A. Cross section showing the notched strips.
B. The way the shutter works.
To make a pin-hole camera, so called because a pin hole takes the place of a lens, form a box of pasteboard or of thin wood 4 inches square and 8 inches long; cut a hole ³⁄₈ of an inch in diameter in one end for the pin hole. Fit a strip of wood ¹⁄₂ an inch thick and 4 inches long, having notches cut into it to a depth of ¹⁄₈ inch, to the sides of the box as shown at [A in Fig. 56]. These notched strips are to hold a sensitized dry plate.[47] Next make a shutter, that is, a little device to open and close the pin-hole; it is simply a bit of sheet brass 2¹⁄₂ inches long, ¹⁄₄ inch wide at one end and ¹⁄₂ an inch wide at the other end as shown at [B]. Drill a hole ¹⁄₈ inch in diameter in the center of the strip of brass and pivot this to the front of the box so that it is on a horizontal line with the center of the hole.
[47] A dry plate is a sheet of glass coated on one side with gelatin and bromide of silver which makes it sensitive to light.
Now to make the pin-hole, and certainly no pin-hole was ever more important than this one. Glue a thick piece of nice smooth tinfoil over the hole on the inside of the box and with a fairly good-sized pin, or better a needle, prick a smooth hole in the center of it.
You are ready now to take a picture and to do so slip a sheet of ground glass[48] into the grooves in the camera up close and then farther back until you can see the picture plain. This done take the camera into your dark-room,[49] and load a dry plate into it, put the cover on the box and fasten a black cloth over it with a rubber-band as shown at [C in Fig. 56].
[48] You will find [directions] for making it in [Chapter IX].
[49] A dark room must be used because a ray of any kind of light except red will spoil a dry plate the instant it strikes it. A red-lamp can be bought for a quarter or you can make one and either use a sheet of red glass or red dark-room paper.
Go out and point your camera at the object you want to photograph, be it a landscape, a seascape or a scapegoat, press down on the lever for a second, let go of it when it will drop back and cover the pin-hole again and the exposure is made.
How to Develop a Dry Plate.
—Next take your camera into your dark-room and develop the plate, that is, immerse it in a chemical solution called a developer to bring the picture out on it. To do this you must get a tray and put the exposed dry-plate in it, film side up, and pour the developer over it.