Condition: Very good.
The Celestron 6mm Orthoscopic Guiding Eyepiece is a multi-purpose accessory. With it you can obtain more precise star centering for GoTo mount alignment, manually guide long-exposure images, measure double star separations and orientations, and more.
The illuminated reticle pattern comprises a number of elements. In the center is a double-line crosshair with two-ring bullseye. Surrounding this is a grid of squares, which includes a 90° crossline having finer fiducial marks, extending to the outermost perimeter of the reticle pattern. Surrounding all this is a circular ring divided in 15° increments.
The reticle is adjustable in position, via two orthogonally positioned, spring-loaded screws. This X-Y adjustability permits precise positioning that obviates having to move the mount. The eyepiece is adjustable in focus, lockable via a setscrew. The thread-in illuminator requires three GP-189 button batteries (included), and the brightness is varied by a potentiometer having a built-in on-off switch.