Baader Planetarium Alan Gee Mark II Centering Ring for SC 9¼"

Its sole purpose is to adapt the Baader Alan Gee Mark II Telecompressor for use with larger Celestron 9.25" and 11" Schmidt-Cassegrain telescopes. It ensures the telecompressor is held perfectly on the optical axis, which is crucial for preventing image defects.

The baffle tubes of the Celestron 9.25" and 11" SCTs have a different diameter than the 8" models for which the Alan Gee II was originally designed. This ring compensates for that size difference, ensuring the telecompressor's optical elements are precisely centered with the telescope's optics to avoid introducing coma and astigmatism.

No. This ring is specifically for the non-EdgeHD Celestron 9.25" and 11" SCTs. The standard Alan Gee II Telecompressor attaches directly to a C8 without this ring. EdgeHD models have a different optical design and require different reducer solutions.

Installation is straightforward. You first thread the centering ring onto the rear cell of your Celestron 9.25" or 11" SCT. Then, you thread the Alan Gee Mark II Telecompressor into the centering ring. This ensures the entire assembly is secure and optically aligned.

No, you cannot. Attempting to attach the telecompressor without this ring will result in a loose fit and a severely misaligned optical train. This will produce poor quality images with significant aberrations. The ring is a mandatory component for these specific telescopes.

This ring is designed exclusively for the Baader Alan Gee Mark II Telecompressor. It is not intended to work with reducers from other manufacturers, as thread specifications and spacing requirements can vary significantly.