An optical viewfinder is the small window on a camera through which the photographer looks to frame and compose a shot. It provides a direct optical view of the scene, usually through a series of mirrors, prisms, or a simple window aligned with the lens.
Optical viewfinders are common in film cameras, DSLRs, and some compact cameras. They allow photographers to preview the composition in real time without relying on electronic screens, offering a clear, lag-free view that is especially useful in bright sunlight or fast-action photography.