Celestron 6″ Rowe-Ackermann Schmidt Astrograph (RASA) Optical Tube Assembly

The Celestron 6″ Rowe-Ackermann Schmidt Astrograph (RASA) Optical Tube Assembly is a purpose-built astrophotography telescope engineered to deliver exceptionally fast imaging performance for wide-field deep-sky photography. Unlike conventional Schmidt-Cassegrain telescopes, the RASA places the camera at the front of the optical tube, allowing the telescope to operate at an extremely fast f/2.2 focal ratio while maintaining excellent optical correction across a large imaging field.

With a 152 mm aperture and 335 mm focal length, the RASA 6 is ideally suited to imaging expansive emission nebulae, dark nebulae, open star clusters, large galaxies and rich Milky Way star fields. The exceptionally fast optical system allows significantly shorter exposure times than slower astrographs, making it easier to capture faint astronomical objects while reducing demands on mount tracking accuracy.

The patented Rowe-Ackermann Schmidt optical system combines a Schmidt corrector, precision primary mirror and dedicated three-element rare-earth lens assembly to produce a flat, highly corrected field with excellent edge-to-edge sharpness. Celestron’s StarBright XLT optical coatings maximise light transmission and improve contrast, while the optical design delivers sub-arcsecond resolution under favourable seeing conditions.

Designed specifically for modern CMOS astronomy cameras, the RASA 6 supports camera sensors up to 22 mm diagonal with excellent field illumination. The supplied M42 camera adapter provides the required 17.5 mm back focus, making the telescope compatible with many dedicated astronomy cameras. Due to the front-mounted imaging configuration and limited back focus, DSLR and most mirrorless cameras are not suitable for use with this telescope. Likewise, the RASA is designed exclusively for imaging and cannot be used for visual observing.

An integrated filter drawer accepts both 2″ and 1.25″ filters, allowing users to install broadband or narrowband filters while maintaining the correct optical spacing. A removable 2″ clear optical window is supplied as standard, ensuring optimum performance when additional filters are not required.

To help maintain peak optical performance throughout an imaging session, the telescope incorporates an integrated 12 V magnetic-levitation cooling fan that rapidly equalises the optical tube with ambient temperature while helping minimise internal air turbulence.

The compact aluminium optical tube weighs just 3.8 kg, making the RASA 6 well suited to portable equatorial mount setups. A standard CG-5 dovetail bar provides straightforward compatibility with a wide range of astronomical mounts, while the compact dimensions make transport and storage considerably easier than larger astrographs.

Combining extremely fast optics, a highly corrected wide imaging field and an integrated imaging-focused feature set, the Celestron RASA 6 is an outstanding choice for astrophotographers seeking efficient deep-sky imaging with minimal exposure times in a compact and portable optical tube assembly.

Note: The RASA 6 is designed exclusively for astrophotography. It cannot be used for visual observing, and optimum performance is achieved with dedicated astronomy cameras having a maximum 22 mm sensor diagonal and 17.5 mm back focus.