Sometimes referred to as dissecting microscopes, stereo microscopes provide a three-dimensional view of a specimen by using two separate objective lenses and eyepieces. While these microscopes tend to have lower magnification power than conventional compound microscopes, they provide a larger working distance. Stereo microscopes are typically used to view relatively large, solid samples.
There are two main types of stereo microscope: the Greenough design and the common main objective design. The Greenough design allows for a wide range of apertures and is similar to a compound microscope. However, this setup causes a slight tilt in the focal plane and results outside the field of view are under- or over-focused.
The common main objective design does not have a tilted focal plane, but causes another problematic visual effect: the viewed object appears elevated in the middle.