Camera obscura is Latin for “Dark Chamber” and that, really, is all it is. Though we think of “camera” as being associated only with photography, it also means “chamber” or “room,” and a camera obscura is a room where astonishing things can happen with the most rudimentary preparation.

A camera obscura is basically a dark, sealed chamber (from soup-can to room sized) with one tiny hole in it. The light coming in the hole brings with it the image of whatever is outside the chamber and displays it upside-down on the opposite wall!

Since light travels in a straight line, when it passes through a small hole it doesn’t scatter but crosses and reforms upside down. As early as 500 BC Chinese philosophers recorded this phenomenon, astonishing crowds by transforming dark chambers into “locked treasure rooms.” Aristotle built a primitive camera obscura to view solar eclipses, and artists such as daVinci sometimes used them to give their drawings a more lifelike perspective by actually tracing the landscape projected upside-down on a canvas hung inside the chamber.

To build a camera obscura you need an interior space which can be completely sealed against light. An appliance box is ideal, but you can use anything from a potato-chip can to your bedroom. It works better if at least one side of the box faces the outdoors, and best in bright sunlight. Cover any openings with black plastic, cardboard, anything that will completely block all light.

Now you need to make a hole in a wall (or a window covering, if it’s your bedroom)! Experiment with the size. If you are using a small box a hole made by a thumbtack will do; if you are in a room, you may need to cut a hole the size of a nickel for the best results. Your camera obscura will have the sharpest “picture” if the hole you make is in the wall facing the brightest light. It will take your eyes a while to adjust to the dimness of the room but once they have, you should be able to see your image in greater detail. A bigger hole means more light but a less crisp image, a smaller hole shows more detail but is dimmer.

Isn’t that something?