Availability: In stock

  • Flat field free of optical aberrations like field curvature, coma, astigmatism and chromatic aberration across an entire APS-C sensor.

  • Unlike the larger RASAs that work with DSLR and large CCD cameras, the 8” model was designed with color astronomical CMOS cameras, smaller CCD cameras, and mirrorless cameras in mind. The telescope does not work with standard DSLR cameras.

  • NEW Ultra-Stable Focus System – six precision sealed ball bearings virtually eliminate image shift.

  • Integrated air cooling system –12V DC MagLev fan reduces cooldown time and provides optimal air flow while filtering out dust.

  • Internal filter mount – seamlessly accommodates a Light Pollution Imaging Filter into the optical path.

  • CGE dovetail mounting rail.

  • Performs over a wider spectral range than most telescopes, from 390-800 nm, so more of the light passing through the astrograph is in sharp focus.

Our Product #: RASA8
Celestron Product #: 91073
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Product Description

This Celestron 8" f/2 Rowe-Ackermann Schmidt Astrograph (RASA) optical tube has:

Very fast 8" f/2 Rowe-Ackermann Schmidt optics 
StarBright XLT optical multicoatings for the highest possible light transmission
MagLev DC cooling fan and cooling vents 
Built-in corrector lens
Mirror locks
42mm T-thread and C Thread camera adapters
CGE (Losmandy-style "D-plate") dovetails 
2-year warranty

"I don't get it. What do you look through?"

This might be the most common question people ask when you unpack your new Celestron Rowe-Ackermann Schmidt Astrograph (RASA). It's not only missing something that comes with virtually every telescope ever produced . . . an eyepiece . . . it doesn't even have a place to put an eyepiece. That's because the 400mm focal length f/2 Celestron 8" RASA is strictly a deep space imaging scope and cannot be used visually.

But what an imaging scope! It has a 22mm image circle that can handle CMOS cameras, smaller CCD cameras, and mirrorless cameras.  The telescope does not work with standard DSLR cameras. It provides a proven Schmidt corrector optical system with a built-in corrector lens that keeps the images free of coma, field curvature, and false color. The optical quality and spot size across the entire image circle are unprecedented for an astrograph in this price range - or even that of a much more expensive instrument.

Its fast, wide field, f/2 optics give you two huge advantages over traditional f/10 catadioptric imaging scopes (even those using an optional f/6.3 or f/7 focal reducer). Those advantages? Better apparent tracking due to the image scale, plus shorter exposure times due to the speed of the optics. That means you can create better-looking deep space images in a fraction of the time it used to take, even without using an autoguider.

The Celestron RASA concept was to modernize the Celestron Schmidt camera, an instrument that had a loyal following, as its very fast focal ratio allowed amateur astrophotographers to produce wide field deep space images in the 1970s. Schmidt cameras could produce great images, but they wre and imaging scope only a really hard-core astrophotographer could love.

Those Schmidt cameras used a single frame of 35mm film, cut from a roll of film. You flexed the chip of film in total darkness (being careful not to touch the emulsion side) to fit snugly into a curved holder that matched the camera's curved focal plane, then loaded it into the camera by feel inside a black cloth bag to avoid image-spoiling stray light. You manually guided your scope during the entire exposure, keeping your eye glued to the crosshairs of an illuminated reticle eyepiece so your stars wouldn't turn into elongated squiggles. Finally, after a sometimes multiple hour single exposure, you tediously processed the small chip of film in your own darkroom before you could even begin to see if you had captured a usable image.

No more. Telescope mount drive accuracy has improved tremendously, electronic eyeballs have taken over guiding, and fast digital photography has taken the place of slow 35mm film.

Today's CCD camera can have sensors as large, if not larger, than film. To compensate for the new large sensors Celestron had to push the boundaries of the Schmidt camera design and make an entirely new type of instrument. The Celestron Rowe-Ackermann Schmidt Astrograph has provided that advance in the performance of deep space imaging scopes. With it, today's amateur astrophotographers can produce results rivaling that of the best professional observatory photos of only a few short years ago.

As with most advances in optics, the Celestron Rowe-Ackermann Schmidt Astrograph was designed not by committee, but by two dedicated optical experts who believed things could be done better - Dave Rowe and Mark Ackermann.

Dave Rowe - amateur astronomer, telescope maker, and optical designer - studied astronomy and astrophysics at Caltech, has published more than 50 papers, and holds 15 patents. Rowe has designed and fabricated many telescopes for Celestron and PlaneWave Instruments, including PlaneWave's corrected Dall-Kirkham and CDK700 telescope. He also worked closely with Celestron engineers in the development of the unique StarSense technology.

Mark Ackermann - amateur astronomer and experienced optical designer - earned a BS in mathematics and physics from the United States Air Force Academy, an MS in solid state physics, and a PhD in nonlinear optics from the University of New Mexico. He has published dozens of papers on optical telescope design and holds six US patents related to optical systems.

Engineered as a complete astroimaging system, every component of the Celestron Rowe-Ackermann Schmidt Astrograph is optimized for peak performance with CMOS, smaller CCD camers, and mirrorless cameras. Every component of the system has been designed to work together seamlessly, right down to the thickness of the glass used in the scope's fully-multicoated optical window.

Some of the advanced features of the Celestron 8" RASA includes mirror locks hold your precise focus. A quiet high-output 12V internal MagLev fan on the rear cell reduces cooldown time and provides optimal airflow through the dust filtered 24.7" long optical tube. Naturally, industry leading StarBright XLT optical multicoatings are standard equipment for the highest possible light throughput. A Losmandy-style "D-plate" dovetail is standard. The back focus with the included camera adapters is 25mm.

The Celestron #93614 RASA LPR (Imaging Filter is highly recommended with the RASA. The scope's incredibly fast f/2 focal ratio gathers so much light so quickly that even modest amounts of sky glow at a dark sky site can brighten the sky background and reduce the contrast in your images. In light-polluted city and suburban locations, the RASA Light Pollution Reduction (LPR) Imaging Filter is a must.

CameraCompatible with RASA 8?Adapter required
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

(sold separately)

Sony mirrorless with APS-C sensor Yes

Sony mirrorless adapter

(sold separately)

Canon mirrorless with full frame (42mm) sensor Yes, but not optimized across the full sensor

Canon mirrorless adapter

(sold separately)

Sony mirrorless with full frame (42mm) sensor Yes, but not optimized across the full sensor

Sony mirrorless adapter

(sold separately)

DSLR No --

Tech Details

Aperture 8"
Focal Length 400mm
Focal Ratio f/2
Heaviest Single Component 17 pounds
Motorized Controls n/a
Weight 17 pounds
Optical Coatings Starbright XLT
Resolution .68 arc seconds
Supplied Eyepiece n/a
Telescope Type Schmidt-Cassegrain
Warranty 2 years
Back Focus 25mm


Review by:
The Celestron RASA 8 is a good scope and fits perfectly with a 2.4micron pixel size camera. The Celestron Focus Motor completes the set up nicely. (Posted on 10/17/2019)
Review by:
I have only had a chance to take this scope out twice, but so far it is easily the best scope I've ever used. I have two toddlers, and live in an area where I don't get very many days to image. So when I do get a clear night to take pictures, I really need to make the time count. With this scope I've found I can get enough data for 2 or maybe even 3 targets in a single night.

Stars are sharp across the entire field, and far exceed the sharpness of my 8" F4 newtonian.

The only drawback I've seen with this scope is its 400mm focal length, which is a bit wide angle for my preference. (Posted on 8/5/2019)
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Supplied Accessories

M42 camera adapter, C-thread camera adapter, fan battery pack