Pinhole cameras may just be the simplest type of camera ever invented, and they have been around for a long time now. These cameras are used for art, fun, science, and even surveillance. You probably have one, or know someone who does. But have you ever thought about the mechanism behind a pinhole camera?
Not Your Typical Camera
The pinhole camera is not one of the conventional cameras you’re used to in both its form and function. Instead of the typical camera case, a pinhole camera makes use of a light-proof box – matchboxes and cereal boxes will do. And in place of the typical glass lens is a very, very small hole, the size of that created by a pin.
But don’t underestimate this cardboard camera. The fact is the results are impressive and sophisticated works of art. The images you get after exposure is a whole lot better than those you get from a conventional camera. It’s soft, yet crisp at the same time, and the images have an almost infinite depth of field.
This simple camera works on an equally simple principle: Pinhole Optics. One side of the box has a minuscule hole. Light from outside the box passes through the hole and an image is formed on one side of the camera.
For you to understand the concept better, imagine being inside a big, dark box. On one side of the room is a small hole and outside the room is a friend holding a flashlight. Now this friend shines the flashlight through the pinhole, at varying angles.
Imagine the wall opposite the hole. On it will be a small dot created by the beam of the flashlight, shining through the hole. As your friend moves the flashlight, the small dot will also move around the wall.
Now, imagine taking this large box outside and pointing it at your garden. On the wall opposite the hole will be a reversed and inverted image of the landscape. Each point in the garden emits light and the beam emitted from the point will pass through the hole, creating its equivalent point of light on the opposite wall.
Every point of the landscape will do these (emitting of light, passing through the hole, and reflecting to the wall) all at the same time so that an entire image is created on the back wall.
The bigger the scene and the smaller the hole will automatically mean a longer process. But this also means better results. The image will of course be dim, as the hole is very small.
The actual pinhole camera comes in many different sizes. But all the same, it is a lot smaller than the box mentioned above. And instead of a bare wall opposite the hole, the pinhole camera makes use of a sort of film. The film, flattened against the wall, records the light or the image that passes through the hole.
The camera creates a nice, in-focus representation of the scene where you point your camera. The exposure time usually lasts from half a second to several hours, much longer than usual exposure time of your conventional camera. This is because the pinhole can only allow so much light to pass through, but the result is definitely worth the wait.