A reflex finder is a viewfinder system with a mirror placed behind a lens. The light passing through the lens is reflected by the mirror to a focusing screen, usually ground glass. The image formed on this ground glass can be observed directly, giving a waist-level reflex finder, or through a redressing optical device (set of mirrors or prism) for eye-level viewing, giving an eye-level reflex finder.
With a reflex finder, you can focus the image on the ground glass and frame your picture at the same time. It is common to find a device on the center of the ground glass to help precise focusing, for example a split-image or a microprism device. Today's reflex cameras usually incorporate autofocusing.
Reflex finders are found in:
- Single-lens reflex (SLR) cameras, with one lens for both viewing and taking the picture
- Twin-lens reflex (TLR) cameras, with one lens for viewing and one lens for taking the picture
This article was originally based on "Reflex finder" in Camerapedia, retrieved at an unknown date under the GNU Free Documentation License.