Celestron RASA 6 - Rowe-Ackermann Schmidt Astrograph

Flat, distortion-free image field, free from optical aberrations such as field curvature, coma, astigmatism, and chromatic aberration across the entire field, up to a sensor diagonal of 16 mm.

Ultra-stable focusing system – six sealed precision ball bearings prevent image shift.

Integrated air cooling system – a 12V DC MagLev fan with dust protection reduces cool-down time and ensures optimal airflow.

Internal filter drawer – seamlessly integrates an optional light pollution filter into the light path.

Extended field of view: The RASA 6 is optimized for sensors up to 16 mm diagonal and offers a generous 3.8° field of view, easily capturing large celestial objects.

The RASA 6 optics were first used in the Celestron Origin – Intelligent Home Observatory (#821880, €5299) and are now also available as a standalone telescope.

RASA 6" - Rowe-Ackermann Schmidt Astrograph

The portable astrograph from Celestron, the 6" Rowe-Ackermann Schmidt Astrograph (RASA), can capture spectacular wide-angle deep-sky images in seconds. This incredibly fast f/2.2 system is the perfect telescope for modern astronomical CMOS color cameras and smaller CCD cameras.

Thanks to its large aperture ratio and patented optical design, you can produce sharp, detailed images and, in many cases, completely eliminate the need for an autoguider. Weighing only 3.8 kg (8.4 lbs), the 6" RASA is easy to transport, even to the most remote locations.

RASA Performance for Everyone

The 6" RASA is a telescope designed purely for astrophotography, delivering a flat field of view free from optical aberrations and revealing extremely sharp stars across a wide field of view. It enables astronomical images with impressive depth of field and avoids the problems typically encountered with instruments with longer focal lengths (and slower aperture ratios).

The latest addition to the RASA family, the 6" RASA is a significantly more portable and affordable version of the RASA 11, which was launched to great success in 2014. With the 6" RASA, the benefits of the RASA design are now accessible to a wider range of astrophotographers. It shares many features with its "big brother," the RASA 8, including the integrated cooling system, StarBright XLT coating, and the robust CGE dovetail mount.

The 6" RASA is designed exclusively for astrophotography and cannot be used visually. The focal plane is located at the front of the optical system, so the telescope cannot accommodate a conventional eyepiece.

Shorter Exposure Times and Virtual "Real-Time" Observation

Because it's an f/2.2 optical system, astrophotographers can use shorter exposure times to capture details in faint objects. Combined with sensitive cameras and the right "live stacking" software, the 6" RASA also enables near-real-time observation: You can instantly view and stack images on a computer, resulting in brighter and more detailed images than the naked eye can see—even compared to much larger telescopes!

Since shorter exposure times are possible, your mount doesn't need to track with high precision for extended periods. The short 335 mm focal length of the 6" RASA further reduces tracking requirements. In many cases, autoguiding is unnecessary. Weighing only 3.8 kg, this telescope is an excellent match for a wide variety of commercially available mounts.
Ultra-stable focusing system

The RASA 6 also features the improved focusing mechanism, which reduces primary mirror play when focusing, slewing, or tracking the astrograph. Focusing is easier, more accurate, and more stable than ever before. The key to this ultra-stable focusing system lies in two sets of precision bearings, which are precisely aligned and tested during assembly to ensure optimal performance.

Unique optical design
The patented RASA design (US 2016/0299331 A1) consists of a Schmidt corrector plate, primary mirror, lens group, and optical window. The lens group comprises three elements and uses rare-earth elements. The instrument is optimized for the spectral range of 400–700 nm, allowing it to collect and sharply image more light from celestial objects.

... The RASA 6 telescope incorporates a 2" clear glass filter. This can be replaced, for example, with a nebula filter of the same thickness without introducing any additional glass into the focus path. Thus, the focus position and optical performance remain unchanged even when a filter is used.

With many optical systems, the image quality is unaffected by the addition of another piece of flat glass, such as a filter. However, this is not the case with extremely fast systems like the RASA. Our engineers have addressed this issue by incorporating an optical window into the RASA that can be removed and replaced with a filter. This ensures that image quality remains at its highest level even when using a filter or when the camera has its own optical window. Celestron offers a light pollution filter specifically designed for the 6" RASA that replaces the optical window.

All refractive optical surfaces are coated with StarBright XLT, and the primary mirror features an enhanced aluminum coating. This ensures high transmission for the entire system. Compared to the HyperStar system for Schmidt-Cassegrains, the RASA 6 delivers superior optical performance and illumination.

Advanced Features and Versatility

Designed with the modern astrophotographer in mind, the RASA 6 is equipped with numerous features that enhance usability and adaptability:

Built-in Filter System

The integrated filter drawer accommodates both 1.25" and 2" filters, giving you the flexibility to use various broadband and narrowband filters. The removable 2" clear glass filter (i.e., the optical window) allows you to add optional filters as desired without introducing additional glass into the optical path, which could negatively impact performance at f/2.2.

Integrated Cooling System

A 12V MagLev fan draws air through mesh openings to quickly cool the system to ambient temperature, ensuring optimal image quality while keeping internal components dust-free.

M42 Camera Adapter

The included camera adapter for the RASA 6 features a standard M42 thread, facilitating the mounting of a wide variety of astronomical CMOS cameras.

Designed for the Most Modern Cameras

Unlike the larger RASA models, which are optimized for DSLRs and large CCD cameras, the 6-inch model is designed for astronomical CMOS cameras and smaller CCD cameras. Due to the available back focus, the telescope is not compatible with standard DSLR cameras. It is optimized for sensors with a diagonal of up to 16 mm and still performs well with sensors up to 22 mm (22 mm sensors also work well, although reduced field illumination in the corners should be expected). Furthermore, we do not recommend using the RASA 6 with a camera body larger than 75 mm in diameter.

To achieve peak performance, we highly recommend combining this telescope with the Focus Motor, 6" Aluminum Dew Shield, 6" Dew Heater, and 6" RASA Carrying Case (all sold separately). The Focus Motor allows you to electronically adjust for sharp, precise focus using the same computer you use to control your camera. The Dew Shield or Dew Heater helps keep the optics clear during extended observing sessions, especially in humid conditions. When not in use, you can store and transport your RASA in the protective, portable carrying case. The 6" RASA offers the perfect blend of speed, precision, and portability. Its revolutionary optical design and robust mechanical features allow you to image the night sky like never before. A portable astrograph that opens up a vast, boundless universe.

... Technical Specifications
RASA 6 - Rowe-Ackermann Schmidt Astrograph
Product Data

Item Number
822255

EAN Code
4047825060471
Manufacturer
Celetron
Net Weight (kg)
3.85

Optics

Magnification
16 mm (0.63")
Resolution (DAWES)
0.76 arcseconds
Resolution (RAYLEIGH)
0.91 arcseconds
Back Focus
17.5 mm from the included M42 camera adapter
Special Features
Air cooling system, integrated filter holder
Image Field
16 mm (0.63") Ø, 2.74°
Focal Length
335 mm (13")
Light Gathering Power (to the human eye)
472x
Usable Field
16 mm (0.63") Ø, 2.74° At 22 mm (0.86") Ø, 3.15° minimal power loss at the corner of the image field

Obstacle
77 mm (3.03") (46% of aperture)

Optical Design
RASA

Optical Coating
Starbright XLT (Fully multi-coated)

Spot Size
< 1.5 μm RMS across the image circle

Telescope Series
RASA
Telescope Aperture
152 mm (6")
Tube Material
Aluminum
Tube Weight
3.8 kg (8.4 lbs)
Tube Size (Max)
177.8 mm (7")
Tube Length
609.6 mm (24") Length | 177.8 mm (7") Diameter
Coating
StarBright XLT
Wavelength Range
400 - 700 nm
Aperture Ratio
f/2.2

Included Accessories

Focuser
Ultra-stable Focusing system

Includes accessories

M42 camera adapter, battery holder for fan, filter slider with 2" clear glass filter

Viewfinder
Not included