Celestron

The Celestron Off-Axis Guider uses a prism to intercept a small portion of the telescope’s focal plane (outside the field of view of the main imaging camera) to locate a guide star.

Any movement seen by the guide star will be the exact same movement seen by the imaging camera.

Guiding this way will correct for tracking errors, as well as opto-mechanical errors or flexure. The result: better astroimages with pinpoint round stars.

The Off-Axis Guider is an essential astro-imaging accessory for long focal length telescopes that require the most accurate guiding possible.