What optical device did Leonardo da Vinci design to project an image using sunlight?

Leonardo da Vinci studied the camera obscura, an optical device that projects an image through a small opening.

In a camera obscura, light from a scene enters a darkened chamber through a pinhole or lens. The light rays form an image on the opposite surface, usually upside down. Leonardo described and illustrated this effect while investigating vision, light, perspective, and the structure of the eye.

The device was not a photographic camera because it did not record the projected image permanently. An artist could trace the image, however, making the camera obscura useful for studying perspective and proportion. Leonardo’s notes helped connect optical observation with practical drawing.

The camera obscura predates Leonardo, so he should not be credited as its sole inventor. His importance lies in his detailed analysis and in relating the device’s image-forming process to human sight.