Leonardo da Vinci studied the camera obscura, an optical device that projects an outside scene through a small opening.
A camera obscura is a darkened room or box with a tiny aperture. Light from the scene passes through the opening and forms an inverted image on the opposite surface. Leonardo described this effect in his notebooks and used it to investigate vision, light, perspective, and the workings of the eye.
The device was not a photographic camera because it had no film or electronic sensor to preserve the image. It was an optical projection system. Leonardo’s notes helped connect the camera obscura with artistic observation, although historians do not agree that he routinely used one to produce paintings.
The principle is much older than Leonardo. Ancient writers, including Mozi and Aristotle, discussed related observations, and later artists and scientists refined the apparatus. The modern word camera comes from the Latin phrase camera obscura, meaning “dark chamber.”