Suitably shaped prism arrangement built into certain single lens reflex cameras above the ground glass screen to permit observation of the screen image at eye level and to show an upright and right-way round picture.
optical device, usually fitted on 35mm cameras, which makes it possible to view the image while focusing. A mirror device laterally reverses the image so that the scene is viewed through the camera upright and the right way round.
A pentaprism is a five-sided reflecting prism used to deviate a beam of light by 90Â°. The beam reflects inside the prism twice, allowing the transmission of an image through a right angle without inverting it (that is, without changing the image's handedness) as an ordinary right-angle prism would.