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Orion - 8" f/8 Ritchey-Chretien Astrograph Telescope


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Manufactured by: Orion


The Orion 8" Ritchey-Chretien Astrograph Telescope is ideal for use with small CCD-chip cameras such as Orion's award-winning StarShoot line, as well as medium-format CCD and DSLR cameras for deep-sky and solar system astrophotography. The telescope's wide, fully illuminated flat field produces pinpoint star clarity all the way to the edge of the camera's sensor.

The Orion 8" Ritchey-Chretien Astrograph features a precision machined, dual-speed (10:1) linear-bearing Crayford-style focuser with an engraved millimeter scale on the drawtube. The robust focuser provides precise fine focus adjustment without slippage or flexure with heavy accessories attached. One 2-inch and two 1-inch extension rings are included for adjusting the focus position for various cameras. Focus travel readily accommodates popular imaging accessories. 

As most successful astrophotographers will tell you, the more light you can gather, the better the quality of your astrophotos.   Combine light-gathering ability with a compact design and an affordable price, and you've described the new 8" f/8 Ritchey-Chretien Astrograph. As a leading supplier of affordable imaging equipment and solutions for amateur astronomers, Orion has proudly introduced this highly regarded telescope design to their already highly regarded product line. Advanced astrophotographers and professional observatories worldwide have enthusiastically endorsed the Ritchey-Chretien optical design. Even the Hubble Space Telescope is a Ritchey-Chretien and it continues to produce some pretty fair images!

Previously available only in larger apertures that cost thousands more, the outstanding optical design of the Orion 8" Ritchey-Chretien Astrograph allows the user to capture spectacular, detailed images of deep-sky objects like never before.  In contrast to conventional Newtonian reflector and Schmidt-Cassegrain designs that are susceptible to coma away from the center of the field, the Ritchey-Chretien utilizes hyperbolic primary and secondary mirrors to achieve wonderfully flat images that are virtually coma-free. In the 8" model, the mirrors are made of BK-7 optical glass with enhanced aluminum 94% - 96% reflectivity coatings, to provide diffraction-limited performance. Since there are no lenses involved, images are also free from chromatic aberration, which affects all but the finest, most expensive apochromatic refractors.

Orion Ritchey-Chretien Astrographs have been designed with collimation in mind. With an optical instrument of this caliber, precise optical alignment is of paramount importance. Each Orion RC secondary mirror is precisely center-marked to facilitate collimation and even includes a Cheshire collimation tool to make proper alignment of optics as convenient as possible.

The 21-inch enameled steel optical tube weighs only 15.8 lbs. and features a dovetail mounting bar underneath, for trouble-free setup on medium or large-sized Orion equatorial mounts. The inside of the optical tube is fortified with ten computer-positioned light baffles, and the primary mirror baffle tube and secondary mirror light shield are also highly baffled to ensure maximum image contrast.

Without a doubt, the 8" Ritchey-Chretien Astrograph brings advanced astrophotography performance into the realm of affordability for most amateur astronomers. More affordable than comparably sized apochromatic refractors and without the coma that normally affects Newtonian reflectors, the Orion 8" f/8 Ritchey-Chretien Astrograph Telescope takes astrophotography to a new level.



  • 8" aperture Ritchey-Chretien telescope produces wonderfully flat, virtually coma-free astrophotographs that are superior to those achievable with conventional reflector or Schmidt-Cassegrain telescopes of the same aperture
  • Ideal for use with both small and medium-format CCD astrophotography cameras and DSLRs; provides a wide, fully illuminated field and pinpoint star clarity out to the edge of the camera's sensor
  • Features a rotatable, machined, dual-speed (10:1) linear-bearing Crayford focuser that provides fine focus adjustment without slippage or flexure with heavy accessories attached
  • Designed with collimation in mind, Orion RC's feature a precisely center-marked secondary mirror and include a Cheshire collimating tool, making them the most convenient RC's to collimate available
  • Imaging contrast is optimized by virtue of ten computer-positioned baffles in the optical tube, four internal baffles in the primary mirror tube, and an internally glare-threaded secondary mirror light shield


                                                                              ONE RATHER LARGE RITCHEY-CHRETIEN !








Additional Information

Name Orion - 8" f/8 Ritchey-Chretien Astrograph Telescope
Manufacturer Orion
Model ORI-08958
Manufacturer Part No ORI-08958
Telescope Aperture 7.1" - 8"
Aperture 200mm
Diameter 200mm
Finderscope None
Focal Length 1600mm
Focal Ratio f/8.0
Focuser 2" dual-speed linear bearing Crayford
Highest Useful Magnification 300x
Included Accessories Two 1" and one 2" removable extension tubes, Orion collimation tool
Limiting Stellar Magnitude 14.2
Lowest Useful Magnification 29x
Optical Design Ritchey-Chretien
Optical Tube Length 21.8 in.
Optical Tube Weight 15.8 lbs.
Secondary Mirror Obstruction 97mm
Secondary Mirror Obstruction by Area 23%
Secondary Mirror Obstruction by Diameter 48%