Closed system

A closed system in the context of a stereoscope refers to viewers in which the stereoview is placed in an enclosed housing. The observer effectively looks through the lenses into a dark chamber, resulting in an intimate viewing experience and improved image quality due to reduced reflections and enhanced contrast.

A disadvantage of a closed system is that the viewer is typically suited to a single stereoview format, as the dimensions of the housing are tailored to that format, in contrast to open system viewers.