Leonardo da Vinci studied the camera obscura, an optical device that projects an outside scene into a dark room.
A camera obscura works when light passes through a small opening into a darkened space. Rays from the outside scene form an image on the opposite surface, producing a projection that is typically inverted. The principle is the ancestor of the photographic camera.
Leonardo used the phenomenon in his investigations of vision, light, perspective, and image formation. His notes describe how light rays behave and how a projected scene relates to the objects outside the chamber.
The camera obscura was not invented by Leonardo; similar optical observations existed earlier. Leonardo’s importance lies in his detailed study and explanation of the device, which is why it is frequently included among the technologies connected with his notebooks.