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Pinhole Camera
A pinhole camera, or camera obscura [3] (meaning "dark room" in Latin), is a closed box or room with a tiny hole on one side [4]. As we can see in Figure 2, light from outside the box passes through the hole and forms an image on the opposite side of the box. Pinhole cameras are fun to build and can be made from ordinary materials [5]. The image formed inside the pinhole camera, as we notice, looks exactly as it would look from our own perspective, only upside-down [6]. The size of the objects in the image depends on the objects' distance from the pinhole – the farther they are, the smaller they will look. This is true in our own perspective as well. For example, even though the width of the tracks in Figure 3 is the same along their entire length, sections that are closer to us look much wider than sections that are further away. Designing a pinhole camera presents an interesting dilemma. To form a really sharp image, the pinhole must be tiny, but if it is tiny, only a small amount of light will be able to pass through, making the image dim. On the other hand, while making the pinhole large would allow more light to pass through, it would also make the image blurry. Indeed, it is not possible for a pinhole camera to capture an image that is both bright and sharp [4]. The lens, however, is designed to do exactly that.
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