Designed for use with refractor and Schmidt-Cassegrain (SCT)-type telescopes, the 2" Alpine Astronomical Baader 1.8x Glasspath Corrector is primarily intended to improve contrast and correct chromatic aberration and fringing—especially when using binoviewers. It is ideal for use with the Maxbright and Mark V binoviewers. For proper use you will need the T-2 Maxbright mirror diagonal for both, and for the Mark V you'll need to add a T-2 change ring. The optical length has to be exact so the manufacturer recommends this combination only.
When using a binoviewer, the distance incoming light must travel to get to your eye is increased, resulting in a lack of enough back focus distance to achieve proper focus. By using this corrector, the focal point of the telescope is extended sufficiently to accommodate the length of the binoviewer.
In addition to providing critical back focus distance, the corrector adds 1.8x magnification in front of the binoviewer eyepieces. This Barlow-type function enables the use of longer focal length eyepieces to achieve high magnifications. These eyepieces tend to have longer eye relief than eyepieces with short focal lengths, so viewing is easier and more comfortable.