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Celestron 8” RASA OTA
Celestron 8” RASA OTA
Celestron 8” RASA OTA
Celestron 8” RASA OTA
Celestron 8” RASA OTA
Celestron 8” RASA OTA
Celestron 8” RASA OTA
Celestron 8” RASA OTA
Celestron 8” RASA OTA
Celestron 8” RASA OTA
Celestron 8” RASA OTA
Celestron 8” RASA OTA
Celestron 8” RASA OTA
Celestron 8” RASA OTA
Celestron 8” RASA OTA
Celestron 8” RASA OTA

Celestron 8” RASA OTA

by Celestron
SKU CEL-91073
CA$3,057.00 - CA$3,057.00
CA$3,057.00
CA$3,057.00 - CA$3,057.00
CA$3,057.00
Price Match Policy!
  • 203mm (8") Rowe-Ackermann Schmidt Astrograph
  • Incredibly fast 400mm f/2.0 optical system
  • 22mm optimized image circle for sharp stars edge-to-edge
  • Ultra-Stable Focus System mitigates mirror shift
  • Lightweight 17 lb optical tube for ultimate portability
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Downloads
  • Warranty

  • Celestron 8” Rowe-Ackermann Schmidt Astrograph (RASA 8)

    The Celestron 8” Rowe-Ackermann Schmidt Astrograph (RASA 8) combines a 203mm (8") aperture with an exceptionally fast f/2.0 optical system to create a premier wide-field imaging instrument. Its 400mm focal length captures vast swaths of the night sky, while its patented design delivers 843x the light gathering power of the human eye, enabling you to capture detailed deep-sky images in a fraction of the time required by conventional telescopes. The RASA 8 delivers pinpoint stars smaller than 2.3 μm RMS across its optimized 22mm image circle, all within an optical tube that weighs just 17 lbs (7.7 kg).

    The RASA f/2.0 Optical System: 843x Light Gathering Power

    The RASA 8’s f/2.0 focal ratio is its defining feature, allowing you to use dramatically shorter exposure times to capture faint nebulae and galaxies. This speed, combined with today's sensitive CMOS cameras, makes a near-real-time observing experience possible through live stacking. The relatively short 400mm focal length lessens the demands on your equatorial mount's tracking, often eliminating the need for an autoguider entirely. StarBright XLT optical coatings ensure maximum light transmission across a wide 400-800 nm wavelength range.

    Optimized for CMOS & Mirrorless: A 22mm Flat-Field Image Circle

    Engineered for modern cameras, the RASA 8 produces a flat, coma-free field across its 22mm optimized image circle, ensuring sharp stars from edge to edge on smaller CCD and color CMOS sensors. Performance remains strong across a useable field of 32mm, making it an excellent match for APS-C mirrorless cameras. An integrated filter mount within the optical path simplifies your imaging train. This astrograph is a dedicated imaging instrument and cannot be used with DSLRs or for visual observation.

    Ultra-Stable Focuser and 17 lb Portability

    Celestron's Ultra-Stable Focus System uses a precision linear ball bearing to support the primary mirror, preventing the lateral movement or "mirror shift" that can plague other designs during focusing or slewing. This ensures your focus is easier to achieve and holds firm throughout an imaging session. At only 17 lbs (7.7 kg), the RASA 8 optical tube is highly portable and pairs perfectly with a wide range of mid-capacity equatorial mounts, making it easy to transport to dark-sky sites.

    • Air-Cooling System: An integrated 12V MagLev fan helps the optics reach thermal equilibrium quickly for the sharpest possible images.
    • CGE Dovetail Bar: A wide, sturdy CGE-style dovetail provides a secure connection to your mount.
    • Included Adapters: Comes with 42mm T-thread and C-thread adapters to connect a wide variety of astronomical cameras.

    RASA 8 vs. RASA 11: Portability and Sensor Compatibility

    The RASA 8 offers the core benefits of the RASA design in a more compact and accessible package compared to its larger sibling, the RASA 11.

    • RASA 11 Advantage: With its 11" aperture and 43.3mm image circle, the RASA 11 is built to illuminate large full-frame sensors (42mm diagonal) and offers greater light-gathering power for the most demanding imagers.
    • RASA 8 Advantage: The RASA 8 weighs in at a mere 17 lbs, compared to the RASA 11's 43 lbs, making it far easier to mount, transport, and manage. Its 22mm optimized image circle is perfectly matched to the smaller, highly efficient sensors in today's most popular color CMOS and mirrorless cameras, providing a cost-effective entry into high-speed, wide-field astrophotography.

  • What kind of mount do I need for the RASA 8?

    With an optical tube weight of just 17 lbs (7.7 kg), the RASA 8 is compatible with a wide range of equatorial mounts. A mount with a payload capacity of 30 lbs or more is recommended to comfortably handle the OTA plus the weight of your camera and any accessories.

    Can I use my DSLR camera with the RASA 8?

    No. The RASA 8 is not compatible with DSLR cameras because the camera body is too large and would obstruct a significant portion of the telescope's aperture. It is designed specifically for smaller-bodied astronomical CMOS/CCD cameras and mirrorless cameras.

    Is autoguiding necessary with the RASA 8?

    Often, it is not. The combination of the RASA 8's extremely fast f/2.0 focal ratio (allowing for very short exposures) and its short 400mm focal length significantly reduces tracking accuracy demands on your mount. For many targets, you can achieve excellent results without the complexity of an autoguider.

    What is the difference between the 22mm optimized and 32mm usable image circles on the RASA 8?

    The 22mm optimized image circle is the area where the optical performance is highest, delivering spot sizes less than 2.3 μm RMS. The 32mm useable field extends this to accommodate larger sensors, like APS-C, with only minimal performance loss at the very edges of the frame.

    How will the RASA 8 perform on the Andromeda Galaxy (M31) with an APS-C camera?

    The RASA 8 is an exceptional instrument for the Andromeda Galaxy (M31). Its wide 400mm focal length will allow you to frame the entire galaxy and its companions (M32 and M110) comfortably on a typical APS-C sensor. The f/2.0 speed means you can capture the faint outer dust lanes with much shorter total integration time than with a slower telescope.

    Can I use the RASA 8 for imaging planets like Jupiter or Saturn?

    While possible, it is not ideal. The RASA 8 is a wide-field instrument with a short 400mm focal length, which will result in very small image scales for planets. Telescopes with much longer focal lengths (2000mm or more), like a Schmidt-Cassegrain, are better suited for capturing detailed planetary images.

  • Optical Design Rowe-Ackermann Schmidt Astrograph
    Aperture 203mm (8")
    Focal Length 400mm (15.74")
    Focal Ratio f/2.0
    Image Circle 22mm (.86") Ø, 3.15°
    Useable Field 32mm (1.26") Ø, 4.6°
    Spot Size < 2.3 μm RMS across image circle
    Central Obstruction Diameter 93mm (3.66") (46% of aperture)
    Light Gathering Power 843x (Compared to human eye)
    Resolution (Rayleigh) 0.68 arc seconds
    Resolution (Dawes) 0.57 arc seconds
    Wavelength Range 400 - 800 nm
    Optical Coatings StarBright XLT
    Back Focus (with included adapter) 25mm (.98")
    Back Focus (from threaded collar) 29mm (1.14")
    Optical Tube Material Aluminum
    Optical Tube Length 628mm (24.7")
    Optical Tube Diameter 235mm (9.3")
    Optical Tube Weight 17 lbs (7.7 kg)
    Dovetail CGE Dovetail Bar
    Focuser Precision Bearing System (PBS)
    Features Air-cooling system, integrated filter mount

    • 8" RASA Optical Tube Assembly

      × 1

    • 42mm T-thread Camera Adapter

      × 1

    • C-thread Camera Adapter

      × 1

    • Fan Battery Pack

      × 1

  • Celestron 2-Year Limited Warranty