Box-type camera obscura

This is a classic example of an English portable camera obscura from the first third of the 19th century. It consists of an empty box, completely lightproof except for a single hole, in which a lens has been fitted. The rays of light from outside enter the inside of the box through the lens and are projected onto the opposite wall, where a mirror is mounted at an angle of 45 degrees, which directs the rays of light to the top, on an emery glass, where the latent image is reflected with its natural colours and shapes, so that the draughtsman can copy it. In addition, this camera obscura has a box inside the other, which allows the user to shorten or lengthen the focal length in order to capture the image as clearly as possible. Portable camera obscuras were widely used by artists during the 18th and early 19th centuries to make the first sketches of their works. This model of camera obscura was also used by early photography experimenters, who wanted to permanently fix the latent images that were viewed inside the camera obscura.