Camera Obscura is an optical that led to photography and the camera. The device consists of a box or room with a hole in one side. It can range in size from a small tabletop device to a room size chamber. the term is Latin for 'Dark Room', which describes the simplest form of Camera Obscura. In the early modern period the camera obscura was used as a model of the structure and function of the eye and as a demonstration of theories of vision. The principle of the camera obscura has been known since ancient times, and the device was used for viewing astronomical phenomena such as solar eclipses from at least the thirteenth century. During the eighteenth century the camera obscura enjoyed widespread popularity, and large camera obscura were constructed for use as public entertainments.