For ETX-90EC, ETX105EC, ETX125EC. 45 degree Erecting Prisms: All ETX models include an internal flat mirror to reflect light to the telescope's 90 degree astronomical observing position. In this position the telescope's image is upright, but reversed. For terrestrial observing the 45 degree Erecting Prism results in a correctly oriented image and a convenient 45 degree observing angle.
