Prisms & Diagonal mirrors

Star diagonals are important devices that divert the path of the beam of light coming from the telescope so that you do not have to strain to see, but can view comfortably and hence enjoy your observing more. The star diagonal’s prism deflects the light by 90°. Refractors, Schmidt-Cassegrain and Maksutov optics often need this device.

Amici prisms divert the light, usually by 45° or even 90°, providing an upright and non-reversed image for terrestrial observing.