The camera obscura, or dark room, has fascinated people for hundreds of years. Originally used to view solar eclipses, they were recognised as an aid to drawing by the late 15th century.
The introduction of a lens in the 17th century greatly enhanced the instrument, and by the late 19th century they had become popular seaside attractions, some of which still survive today.
To make a camera obscura paint the inside of a cardboard box black. Cut out a window in one side and line this window with tracing paper. Make a small hole in the centre of the other side of the box, directly opposite the window. Direct this towards a very bright object and view the image in the window. If the image is too dark increase the size of the hole. More light will get through, but the image will be more blurred. To compensate for this use a magnifying glass to focus the image. The image will be upside down. You could amend your design to hold a movable lens, or create a pinhole camera to take pictures. Create a large camera obscura by using a darkened room on a bright day. Make a small hole in one of the blinds and an image will appear on the opposite wall, showing the scene outside the window.
Making a camera obscura is a wonderful activity for exploring how the eye works, optics, the history of technology and art.
Sophie Duncan is a physicist and programme manager with Planet Science (formerly Science Year) www.planet-science.com