Camera obscura

An optical device or darkened room in which light passing through a small opening projects an inverted image of an outside scene onto a surface.

Pinhole camera: A camera that forms an image through a tiny aperture rather than a lens. It is the simplest portable camera obscura, with the aperture itself producing the image.
Mozi: A Chinese philosopher traditionally dated to the fifth century BCE and founder of Mohism. A passage attributed to him describes image formation through a small opening, an early account of camera-obscura geometry.
Solar eclipse: An astronomical event in which the Moon passes between Earth and the Sun, obscuring the Sun partly or completely. A camera obscura projects a safe image of the Sun for observing an eclipse.
Optics: The branch of physics concerned with the behavior and properties of light. The camera obscura is a direct demonstration of light projection and image formation.
Image formation: The physical process by which light from an object produces a spatially organized image. It explains how rays passing through the opening map the outdoor scene onto the opposite surface.
Aristotle: An ancient Greek philosopher whose works range across logic, nature, and politics. He noted that sunlight passing through gaps could produce crescent-shaped images during an eclipse.
Perspective (graphical): A system for representing three-dimensional space on a flat surface through projected lines and scale. Artists used camera-obscura images as guides to the geometry of perspective.
Focal length: The distance at which a lens or mirror brings parallel rays to a focus. In lens-equipped versions, it helps determine image size and the distance needed for a sharp projection.
Rectilinear propagation of light: The approximation that light travels in straight lines through a uniform medium. Straight ray paths make each point in the scene project to a corresponding point on the screen.
Ibn al-Haytham: An Arab mathematician and physicist whose work shaped the study of optics. His experiments with a darkened room and aperture helped explain image projection and vision.

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