So long ago that no one can say when, it was discovered that if one were in a room shuttered so as to be quite dark, except for the light entering a small hole, say, in the shutter, an image of any object in the sunshine and directly facing that hole would be projected in reverse position upon the opposite wall of the room.
This phenomenon was apparently known to Aristotle, and down through the later centuries. It seems to have been known to Roger Bacon in the thirteenth century and to Leonardo da Vinci in the fifteenth.
In the latter part of the fifteenth century several experimenters found ways to show the image in a natural position by the use of a mirror to reflect the rays, or by inserting a small lens in the aperture through which the rays passed.
But it was not until the early seventeenth century, when the German astronomer, Johannes Kepler, was finding practical use for the plaything in his observations on the size of the sun and moon, that it acquired a name. He called it camera obscura, literally, “dark chamber.”
The later British physicist, Robert Boyle, found that it was not necessary to darken an entire room, but that a small box, fitted with a lens at one end, would serve the purpose admirably. Paper stretched across the opposite end received the image.
The camera obscura, or camera as it was then sometimes called, made little advance during the next hundred years or so, except by an occasional use of additional lenses or a reflecting mirror.
In 1802, however, Thomas Wedgwood announced to the British Royal Institution that he had been able to find “a method of copying paintings upon glass and of making profiles by the agency of light upon nitrate of silver.”
From that time the camera obscura became the camera that we know today.