When you see an image, you see it front ways up, this is only because your brain makes that happen. When the light of the image enters your eye, it is upside down, this is because light travels in straight lines (as shown in the diagram). It enters your eye upside down and your brain flips it the right way up. It's exactly the same for the Camera Obscura.
The camera obscura is an ancient optical device. In its most basic form it is, quite simply, a dark room with a small hole in one wall. On the wall opposite the hole, an image is formed of whatever is outside. This image is upside-down (inverted) and back to front (laterally transposed). The size of the hole has a great effect on the picture that is being projected. A small hole produces a sharp image, which is dim, while a larger hole produces a brighter picture which is less well focused. |