Reflex finder
Looking down into a reflex finder, of the Hasselblad 500C/M image by Dries van den Elzen (Image rights) |
A reflex finder is a viewfinder system employing a mirror placed behind a lens. The light passing through the lens is reflected upwards by the mirror, and focused onto a ground glass. The image formed on this ground glass can be observed directly, in a waist level finder; or it may be optically redirected (with a set of mirrors or a prism) for eye-level viewing, giving an eye level 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 device or a microprism. Today's reflex cameras usually incorporate autofocus; so the reflex image is no longer the primary method of focusing.
Reflex cameras may be classified as:
- single lens reflex or SLR cameras, using the same lens for viewing and making the exposure
- twin lens reflex or TLR cameras, with one lens for viewing and one lens for taking the picture
Inside the lens throat of an SLR, the reflex mirror and groundglass focus screen are visible image by Voxphoto (Image rights) |