Celestron Erect Image Prism

Daytime and Terrestrial Viewing Enhancement

Most telescopes, including refractors and catadioptric models like the popular Schmidt-Cassegrain, are suitable for both astronomy and daytime terrestrial observations. To optimize your telescope for terrestrial use, an erect-image diagonal is the most valuable accessory.

Image Orientation Correction

Standard mirror or star diagonals often produce images that are inverted, mirrored, or both, which is acceptable for celestial viewing but can be confusing for tracking terrestrial objects such as boats or birds. Installing the Celestron 45º Erect Image Diagonal corrects this issue by providing images that are right side up and correctly oriented left-to-right.

Design and Comfort

This erect-image diagonal uses a 45º Amici prism, offering a comfortable viewing angle ideal for daytime observations when the telescope is typically positioned horizontally.

Compatibility Note

Adding an erect-image diagonal to a Newtonian reflector will not produce correctly oriented images due to the optical design of Newtonian telescopes, which inherently produce rotationally offset images. While Newtonians can still be used for daytime viewing, users should be aware that image orientation will not be realistic.