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Fast Astrographs

Fast astrographs work at f/2 to f/2.2, which means they collect the same signal in about a quarter of the time of an f/4 telescope. A few hours of total exposure can show faint dust and nebulosity that would take a full weekend with a slower system. This collection holds the Celestron RASA family, from the 6-inch to the 36 cm, and the Sky-Watcher HAC125DX.

That speed comes with rules. The camera sits in front of the optics, so its size and cabling affect the image. Focus tolerance is tiny, and tilt shows immediately in the corners. Set up correctly, these telescopes are a lot of fun. Set up carelessly, they are frustrating. We help you get it right.

Filters

CA$6,254.00 - CA$6,254.00
CA$6,254.00
CA$6,254.00 - CA$6,254.00
CA$6,254.00

Celestron 11" RASA V2 OTA - CGE Dovetail

279mm (11") Rowe-Ackermann Schmidt Astrograph Extremely Fast f/2.2 Focal Ratio 620mm Focal Length for Wide-Field Imaging 43.3mm Optimized Image Ci...

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CA$6,254.00 - CA$6,254.00
CA$6,254.00
CA$6,254.00 - CA$6,254.00
CA$6,254.00
CA$20,849.00 - CA$20,849.00
CA$20,849.00
CA$20,849.00 - CA$20,849.00
CA$20,849.00

Celestron 36 cm RASA V2 OTA - CGE Dovetail

355.6mm (14") Rowe-Ackermann Schmidt Astrograph Optical Design Ultra-fast 790mm focal length at an f/2.2 focal ratio Covers a 60.1mm image circle,...

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CA$20,849.00 - CA$20,849.00
CA$20,849.00
CA$20,849.00 - CA$20,849.00
CA$20,849.00
CA$3,057.00 - CA$3,057.00
CA$3,057.00
CA$3,057.00 - CA$3,057.00
CA$3,057.00

Celestron 8” RASA OTA

203mm (8") Rowe-Ackermann Schmidt Astrograph Incredibly Fast f/2.0 Optical System 400mm Focal Length for Wide-Field Views 22mm Optimized Image Cir...

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CA$3,057.00 - CA$3,057.00
CA$3,057.00
CA$3,057.00 - CA$3,057.00
CA$3,057.00
CA$4,030.00 - CA$4,030.00
CA$4,030.00
CA$4,030.00 - CA$4,030.00
CA$4,030.00

Celestron Advanced VX 800 RASA Telescope

203mm (8") Rowe-Ackermann Schmidt Astrograph Incredibly fast f/2.0 optical system with 400mm focal length Advanced VX computerized German equatori...

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CA$4,030.00 - CA$4,030.00
CA$4,030.00
CA$4,030.00 - CA$4,030.00
CA$4,030.00
CA$3,335.00 - CA$3,335.00
CA$3,335.00
CA$3,335.00 - CA$3,335.00
CA$3,335.00

Celestron Advanced VX RASA 6"

152mm (5.98") Rowe-Ackermann Schmidt Astrograph Ultra-fast f/2.2 focal ratio with 335mm focal length Advanced VX computerized German equatorial mo...

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CA$3,335.00 - CA$3,335.00
CA$3,335.00
CA$3,335.00 - CA$3,335.00
CA$3,335.00
CA$5,003.00 - CA$5,003.00
CA$5,003.00
CA$5,003.00 - CA$5,003.00
CA$5,003.00

Celestron CGEM II 800 RASA Telescope

203mm (8") f/2.0 Rowe-Ackermann Schmidt Astrograph 400mm focal length for ultra-wide deep-sky fields CGEM II mount provides a 40 lb instrument cap...

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CA$5,003.00 - CA$5,003.00
CA$5,003.00
CA$5,003.00 - CA$5,003.00
CA$5,003.00
CA$8,339.00 - CA$8,339.00
CA$8,339.00
CA$8,339.00 - CA$8,339.00
CA$8,339.00

Celestron CGX 1100 RASA Equatorial Telescope

279mm (11") Rowe-Ackermann Schmidt Astrograph Fast f/2.2 focal ratio and 620mm focal length 43.3mm optimized image circle, excellent performance u...

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CA$8,339.00 - CA$8,339.00
CA$8,339.00
CA$8,339.00 - CA$8,339.00
CA$8,339.00
CA$5,976.00 - CA$5,976.00
CA$5,976.00
CA$5,976.00 - CA$5,976.00
CA$5,976.00

Celestron CGX 800 RASA Telescope

203mm (8") Rowe-Ackermann Schmidt Astrograph Ultra-fast f/2.0 optical system with 400mm focal length 55 lb capacity computerized German Equatorial...

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CA$5,976.00 - CA$5,976.00
CA$5,976.00
CA$5,976.00 - CA$5,976.00
CA$5,976.00
CA$10,424.00 - CA$10,424.00
CA$10,424.00
CA$10,424.00 - CA$10,424.00
CA$10,424.00

Celestron CGX-L 1100 RASA Equatorial Telescope

279mm (11") Rowe-Ackermann Schmidt Astrograph Ultra-fast f/2.2 focal ratio for reduced exposure times 620mm focal length for wide-field imaging 43...

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CA$10,424.00 - CA$10,424.00
CA$10,424.00
CA$10,424.00 - CA$10,424.00
CA$10,424.00
CA$2,362.00 - CA$2,362.00
CA$2,362.00
CA$2,362.00 - CA$2,362.00
CA$2,362.00

Celestron RASA 6" OTA

152mm (5.98") Rowe-Ackermann Schmidt Astrograph Ultra-fast f/2.2 focal ratio for extremely short exposures 335mm focal length ideal for wide-field...

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CA$2,362.00 - CA$2,362.00
CA$2,362.00
CA$2,362.00 - CA$2,362.00
CA$2,362.00
CA$1,380.00 - CA$1,380.00
CA$1,380.00
CA$1,380.00 - CA$1,380.00
CA$1,380.00

Sky-Watcher HAC125DX Minigraph f/2 Astrograph

125mm (4.9 inches) Honders Advanced Catadioptric Optics Extremely Fast f/2 Focal Ratio 250mm Focal Length for Wide-Field Imaging 16mm Image Circle...

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CA$1,380.00 - CA$1,380.00
CA$1,380.00
CA$1,380.00 - CA$1,380.00
CA$1,380.00
CA$3,300.00 - CA$3,300.00
CA$3,300.00
CA$3,300.00 - CA$3,300.00
CA$3,300.00

Sky-Watcher Starlux 190MN

190mm Maksutov-Newtonian Optical Design 1000mm Focal Length f/5.3 Focal Ratio 64mm Secondary Mirror 2" Dual-Speed Crayford Focuser 12.5 kg OTA Wei...

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CA$3,300.00 - CA$3,300.00
CA$3,300.00
CA$3,300.00 - CA$3,300.00
CA$3,300.00

What to Know Before You Buy

  • Camera size: The camera blocks part of the aperture. Compact cameras like APS-C cooled models or small mirrorless bodies with the right adapter work best.
  • Filters at f/2: Narrowband passbands shift in a fast light cone. Choose filters designed for fast optics, often labelled Highspeed or f/2.
  • Tilt and spacing: Small errors show as elongated stars in one corner. A tilt adjuster can help.
  • Collimation: RASA telescopes ship collimated, but transport can shift them. Learning to check it is part of owning one.
  • Mount: A RASA 8 is comfortable on an Advanced VX or CGEM II class mount. The 11-inch and 36 cm need CGX or CGX-L class mounts.

What We Check Before You Order

  • Camera footprint: We compare your camera's diameter and cable exits with the obstruction the corrector can tolerate.
  • Adapter and back-focus: We confirm the adapter for your camera body and the exact spacing to the corrector.
  • Filter choice: We recommend filters made for f/2 light cones, so narrowband signal is not lost.
  • Mount class: RASA 8 on Advanced VX or CGEM II, RASA 11 and 36 cm on CGX or CGX-L class mounts.

Fast Astrographs: Frequently Asked Questions

Can I use a RASA visually?

No. There is no eyepiece position. These are camera-only instruments.

Do fast astrographs work from the city?

Yes, especially with a dual-band filter made for fast optics. Short exposures also reduce the impact of satellite trails and poor guiding.

Do I need autoguiding at f/2?

With short focal lengths and short exposures, many owners image unguided. Guiding still helps for longer subs and for the 11-inch and 36 cm models.

Thinking about a RASA?

Send us your camera and mount model. We will tell you if it fits and what else you need.