Split prism

Glossary Terms

Split image spot (and microprism collar) when defocused image by Voxphoto (Image rights)

A split-Image spot, sometimes called a split image rangefinder or split-prism, is an optical focusing aid sometimes incorporated into a reflex camera's ground glass screen. When the image is out of focus, the two halves of the image appear "split" with a offset between them. When in focus, the halves line up to form a single image. The split is typically horizontal, but sometimes diagonal.

Split-image devices are often combined with microprisms.

Split-image devices in focus screens should not be confused with the coincident rangefinder, fitted to most rangefinder cameras.