twin-lens reflex camera

A twin-lens reflex (TLR) camera features two lenses of the same focal length. One lens captures the image onto the film, while the other serves as a viewfinder, aiding in focusing and framing the shot. This design allows the photographer to see the image continuously on the top screen.

The TLR camera is relatively bulky, with a fixed-mirror reflex housing and a top screen positioned above the film-holding section. Both lenses adjust focus together, ensuring the image on the top screen accurately reflects the sharpness and composition recorded on the film below. While the viewing image is always visible, a slight difference in framing, known as parallax, exists between the top screen and the film due to the separation of the two lenses. This camera type was popular until the advent of 35mm single-lens reflex systems.12