Capture spectacular night sky images with the Celstron RASA 8 Astrograph OTA.

The Celestron 8" RASA utilises a 4-Element, Rare-Earth Glass Rowe-Ackermann Schmidt Astrograph optical design to produce flat field images free of optical aberrations such as chromatic aberration, field curvature, coma and astigmatism. Designed for use on colour astronomical CMOS cameras, smaller CCD cameras and mirrorless cameras. Not compatible with standard DSLRs.

With an insanely fast focal ratio and a unique optical design weighing just 7.7kg, Celestron's RASA 8 is a remarkable optical device with plenty of potential.

 

A true astrograph.

With an short focal length of just 400mm, the RASA 8 is incredibly fast at f/2.0. It is a dedicated astrograph designed specifically for deep-sky astrophotography, with the 8-inch aperture providing a light gathering power 843x that of a human eye. Take razor-sharp images across the night sky, with pin-point stars and a field illumination far beyond the capacity of a SCT with a Hyperstar.

The 8" RASA is much affordable and portable than the huge RASA 11, but still offers many of the benefits of the patented Rowe-Ackermann Schmidt Astrograph optical design. For example, with an integrated air-cooling system, internal filter mount and a robust CGE dovetail mounting bar, the RASA 8 is uniquely versatile.

Note: the 8" RASA is designed exclusively for imaging. It is not designed for visual use. You cannot use an eyepiece with this astrograph as the prime focus focal plane is located at the front of the optical tube assembly.

 

Enjoy the ease of shorter exposure times.

With a focal ratio of f/2.0, the RASA 8 is one of the fastest telescopes on the market. A fast telescope is especially advantageous when capturing faint objects in the night sky, such as deep sky objects, as it requires shorter exposure times to gather detail and light. When paired with an appropriate camera and live-stacking software, the RASA 8 produces images that are immediately brighter and more detailed than much bigger telescopes with a higher f-ratio.

Because of its uniquely short focal length, in most cases, the RASA 8 won't need autoguiding when paired with an equatorial mount. This also means that your polar alignment doesn't need to be perfect, as your EQ mount won't need to track for extended periods of time. And since it only weighs 7.7kg, this OTA is compatible with a range of different mounts.

All in all - this makes the RASA 8 much easier to use than many other telescopes for astrophotography.

 

With the world-renowned Ultra-Stable Focus System.

When the RASA 8 was launched, it created excitement within the astronomy community with the release of the Ultra-Stable Focus System (USFS). Celestron unveiled a unique focuser that utilises a precision linear ball bearing to virtually eliminate image shift, or the lateral movement of the primary mirror during focusing, slewing and tracking. Enjoy smoother and more precise focusing with the RASA 8.

The RASA 8 is also compatible with the Celestron Focus Motor, which enables electronic focusing, making astrophotography even less of a hassle.

 

Compatible with modern astronomical & mirrorless cameras.

Unlike the larger RASAs, Celestron's RASA 8 is designed for use on Colour Astronomical CMOS, Smaller CCD & Mirrorless Cameras. It is not compatible with standard DSLRs.

The RASA 8 is optimised for sensors with a diagonal of up to 22mm, but accommodates sensors with up to a 32mm diagonal comfortably. APS-C sensors in mirrorless cameras are a great choice, for example. Full-frame 42mm cameras will also work, but expect performance to be sub-optimal at the edges of the sensor with a lower field illumination. We also don't recommend pairing your RASA 8 with any camera body larger than 4-inches in diameter.

Please refer to the compatibility chart below for more details.

 

Camera	Compatible with RASA 8?	Required Adapters
Astronomical CMOS/CCD Camera with C-Mount	Yes	C-Mount Adapter (Included)
Astronomical CMOS/CCD Camera with M42-Thread Mount	Yes	M42 Adapter (Included) with M42 Extension Tubes (Not Included)
Astronomical CMOS/CCD Camera with Other Mount	Yes	Custom Camera Adapter
Canon Mirrorless with APS-C Sensor	Yes	Canon Mirrorless Adapter for RASA 8
Sony Mirrorless with APS-C Sensor	Yes	Sony Mirrorless Adapter for RASA 8
Canon Mirrorless with Full Frame (42mm) Sensor	Yes, but not optimised across the full sensor	Canon Mirrorless Adapter for RASA 8
Sony Mirrorless with Full Frame (42mm) Sensor	Yes, but not optimised across the full sensor	Sony Mirrorless Adapter for RASA 8
DSLR	No	--

 

Full Specifications

Optical Tube Assembly (OTA)

Optical Design	Rowe-Ackermann Schmidt Astrograph (RASA)
Aperture	203mm (8-inches)
Focal Length	400mm (15.74-inches)
Focal Ratio	f/2.0
Central Obstruction Diameter	93mm (3.66") 46% of Aperture Diameter
Light Gathering Power (Compared to Human Eye)	843x
Resolution (Rayleigh)	0.68 Arc Seconds
Resolution (Dawes)	0.57 Arc Seconds
Image Circle	22mm (0.86") Ø , 3.15°
Useable Field	32mm (1.26") Ø , 4.6° (only minimal performance loss at edge of FOV)
Wavelength Range	400 - 800nm
Spot Size	< 2.3 μm RMS across image circle
Off-Axis Illumination	93% at 11mm (0.43") Off-Axis
Optical Window	46mm (1.81") Ø
Back Focus with Included Camera Adapter	25mm (0.98")
Back Focus from Top of Threaded Collar	29mm (1.14")
Optical Tube Construction	Aluminium
Optical Coatings	StarBright XLT
Optical Tube Length	628mm (24.7")
Optical Tube Diameter	235mm (9.3")
Optical Tube Weight	7.7kg
Focuser	Ultra-Stable Focus System (USFS)
Ventilation Fan	Yes
Integrated Filter Mount	Yes
Dovetail	CGE Dovetail Bar
Warranty	Celestron 2 Year Warranty

 

Recommended Accessories

	Celestron CGX Equatorial Mount and Tripod A powerful belt-driven mount with a payload capacity of 25kg.
	ZWO ASI2600MC Pro Cooled Colour Astronomy Camera A full format back-illuminated Sony IMX571 sensor, a sensor size of 23.5mm x 15.7mm and a diagonal size of 28.3mm. Weighs just 700 grams.
	Celestron Focus Motor Provides electronic focusing for Celestron Schmidt-Cassegrain, EdgeHD & RASA Telescopes.
	Celestron Deluxe Off-Axis Guider -OAG The most accurate way to guide telescopes with larger focal lengths, compared to using a separate guide scope.

 

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