Leonardo da Vinci described a camera obscura using a dark room and a small opening.
Light entering through the opening projects an inverted image of the outside scene onto an opposite surface. Leonardo studied this optical effect in his notebooks and used it to analyze vision, light, and image formation. The principle does not require lenses, although later camera obscuras often used them.
The camera obscura was not a portable photographic camera and could not permanently record an image by itself. Leonardo also did not invent the underlying phenomenon; earlier writers had described related observations. His contribution was a detailed investigation of how the projection worked and how it related to human sight.