Ancient origins

The camera obscura was the first pinhole

THE ORIGIN OF THE CAMERA

The word "camera" in Latin means a vaulted room or a vault. The "camera obscura," to which the modern day camera owes it origins, was originally a darkened room with a small wall hole through which light entered to project an image on a rear wall or a screen. That image could be easily traced by artists as the beginnings of a painting.

A smaller, portable version of the camera obscura was constructed as a darkened, boxlike device in which images of external objects were received through a small hole to be projected on a surface arranged to receive them. A dark box with a hole through which light can be admitted. That's exactly what every modern camera is. We use the word "aperture" to describe this hole in photography. The device for opening and closing the aperture is called a "shutter." The three principal features that typify most cameras, pinhole or otherwise, are a light-tight box, an aperture and a shutter.

YOU HAVE TO STAND ON YOUR HEAD TO PROPERLY VIEW A PINHOLE IMAGE

Now here's a fact that has fascinated humans for centuries. A pinhole aperture, as the sole source of light entering a dark chamber, will project an upside-down, laterally reversed image of the exterior scene onto a surface inside the box. This is true regardless of the size or shape of the box.

Consider the example of a walk-in pinhole camera - an actual room, say 10 feet by 10 feet and 8 feet high, with every source of light blacked out except for a hole in one wall of about a half-inch in diameter. If you are inside, you will see (once your eyes adjust to the low light level) an image of the outside world, upside down and reversed side to side on the opposite wall.

If you attach your camera (digital or film) to a tripod, focus it on the image on the wall and set your shutter for a long time exposure, you can make an exposure of the scene that is being projected on the wall. You will have to experiment with exposure times since every scene will have its own brightness level. It may take as little as 15 seconds or as long as several minutes. Curiously, if someone walks through the outside scene, you can see their image walking across your interior wall - like a movie projector. Because the person is moving, he or she will likely not be captured by your camera, except perhaps as a blur.

A very small box, say a matchbox, with a pinhole of one tenth of a millimeter, will also contain a similar image. Of course you can't be in the matchbox to see the image, but you can record it by using film or photo paper.

A VIEWING SCREEN REVEALS PINHOLE IMAGE CHARACTERISTICS

While you are inside a walk-in camera, hold a large white mat card or a foamcore board in the light coming through the pinhole. You now have a viewing screen on which the image can be clearly seen. Notice when you move the screen away from the pinhole, objects projected onto it get bigger and become darker. When it is moved close to the pinhole, objects become smaller and brighter. As lightwaves come through the aperture they diverge, basically traveling on the same bearing as they did when approaching the pinhole. The further from the pinhole that the viewing screen is, the more the lightwaves will spread out, creating a larger but dimmer image.

Try holding your viewing screen at an angle to the pinhole. What happens? The proportions of the image change. Why? Some parts of the image on the screen are closer to the pinhole while others are further away, so the image appears stretched out and longer. Now you are getting a feeling not only for how photographic images are made, but also how they can be manipulated.