When the recognition of the arrangement in space of small objects is desired a stereoscopic lens can be used.
No stereoscopic impression is then felt.
Binocular Instruments The stereoscopic microscope is the most suitable for finding out the space taken up by the separate parts of a preparation.
One way of receiving a stereoscopic impression through a microscope is by fixing an apparatus as directly as possible above the last lens of the microscopic objective, which divides the rays passing out and directs half into each eyepiece.
If the perspective centres lie too near one another in the object-space, as may happen with slightly opened and weak systems, the difference of the perspective is then too slight to make any real stereoscopic impression.