pentaprismat

A pentaprism is an optical tool consisting of a prism with five reflecting surfaces. It is primarily used in reflex cameras to redirect the image from the lens to the viewfinder. The pentaprism works by reflecting the light path twice. First, the light from the lens strikes the first reflecting surface and is directed upwards. Then, it strikes a second reflecting surface and is directed forward, inverting the image both horizontally and vertically. This creates an upright, correctly oriented image for the photographer to see in the viewfinder. The pentaprism is an essential component for the functionality of single-lens reflex (SLR) and digital single-lens reflex (DSLR) cameras, allowing for a direct view of what the lens captures. A related optical device is the pentamirror, which achieves a similar function but uses mirrors instead of total internal reflection within the glass of a prism, often resulting in a lighter and less expensive viewfinder system, though generally with a less bright and clear image compared to a pentaprism.