Twin-lens reflex camera

A camera with separate viewing and taking lenses, usually coupled to focus together, that lets photographers compose on a ground-glass screen.

Reflex camera: A camera that uses a mirror to direct light from its lens toward a viewing system. The twin-lens reflex is one design within the broader reflex-camera family.
Taking lens: The lens that forms the image recorded by a camera's image sensor or film. This lens, not the viewing lens, exposes the film in a twin-lens reflex.
Portrait photography: Photography that portrays individuals or groups, emphasizing their appearance or character. The waist-level finder and medium-format negative suited deliberate portrait sessions.
Single-lens reflex camera: A camera that uses one lens for both viewing and image capture, with a reflex mirror in its viewing path. Unlike a twin-lens reflex, it shows the scene through the taking lens.
Ground glass: A translucent, finely textured surface that diffuses light to display an image for focusing. The viewing lens projects its image onto this focusing surface.
Viewing lens: A lens that forms the image shown in a camera's viewing system. It supplies the composition image on the ground glass.
Street photography: Photography of candid or observed scenes in public places. Quiet waist-level composition became a recognizable way to photograph public life.
Rangefinder camera: A camera that focuses by comparing images in an optical rangefinder rather than viewing through the taking lens. It avoids the twin-lens design but also has framing parallax at close distances.
Parallax: The apparent displacement of an object when viewed from different positions. The separated viewing and taking lenses make close subjects shift between framing and capture.
Mirror: A reflective optical surface that redirects light by reflection. A mirror beneath the viewing lens directs its image upward to the screen.

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