Celestron Rowe-Ackermann Schmidt 6″ Astrograph

Celestron Rowe-Ackermann Schmidt 6″ Astrograph (OTA only) with CG5-type dovetail bar.

The new ultra-fast Celestron RASA 6 optical tube is the most compact model in the Rowe-Ackermann Schmidt astrograph family. It allows deep-sky astrophotography enthusiasts to capture stunning wide-field images with extremely short exposure times—without sacrificing pinpoint stars all the way to the edge of the field.

The front optical group consists of three elements made with rare-earth glass, ensuring maximum reduction of chromatic aberration and excellent correction of field curvature, coma, and astigmatism. The StarBright XLT coatings on every optical surface provide light transmission levels close to T=1.

With an impressive f/2.2 focal ratio, the RASA 6 is one of the fastest instruments on the market. It enables imaging of extended deep-sky objects with significantly shorter exposure times compared to traditional optics. In many cases, the short focal length also eliminates the need for autoguiding—an important advantage in terms of portability and simplified setup.

A removable neutral 2” optical filter is integrated into the optical train. It can easily be replaced with any standard 2” filter (or 1.25” filter using the included adapter) without altering the backfocus distance, thus maintaining the native focal ratio.

The Celestron RASA 6” optical tube is compatible with the latest CCD and CMOS astronomical cameras. It is recommended not to use cameras larger than 90 mm in diameter or requiring a backfocus greater than 17.5 mm. For this reason, DSLR and mirrorless cameras—typically larger than 90 mm and requiring longer backfocus—are not compatible with the RASA 6. An M42 threaded adapter is included.

The optical design delivers excellent image quality up to the edge of sensors with a 22 mm diagonal, typical of many modern mirrorless cameras, achieving sub-arcsecond resolution across a 3.8° field of view. The field remains reasonably well corrected even for larger sensors, up to 32 mm diagonal.

The RASA 6” features a 12V DC MagLev cooling fan, designed to speed up tube acclimatization and, when used with dedicated filters, help remove dust from inside the optical tube.

Optional accessories include an additional Vixen CG5-style dovetail bar and a custom padded carrying case.

SPECIFICATIONS