A darkened box with a convex lens or aperture for projecting the image of an external object on to a screen inside, a forerunner of the modern camera.a small round building with a rotating angled mirror at the apex of the roof, projecting an image of the landscape on to a horizontal surface inside.Camera obscura, sometimes referred to as "pinhole image", is the natural optical phenomenon that occurs when an image of a scene at the other side of a screen is projected through a small hole in that.
Widely used by astronomers for observing the sun without causing damage to the eyes, the camera obscura remained largely unchanged until around 1550 when a man called Cardano replaced the pinhole with a lens as described in his book De Subtilitate Libri. dark chamber; after the decussation of the rayes at the hole of the hornycoat, and their refraction upon the Christalline humour, answering the foramen of the window, and the convex or burning-glasses, which refract the rayes that enter it.