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

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The Orion 8" f/8 Ritchey-Chretien Astrograph is excellent for astrophotographers since it is deisgned for use with APS-C and 35mm CCD cameras and DSLRs.

SKU: ORI-08267
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Product Description

The Orion 8" f/8 Ritchey-Chretien Astrograph is excellent for astrophotographers since it is deisgned for use with APS-C and 35mm CCD cameras and DSLRs. A major difference when compared to Schmidt-Cassegrain designs is that Ritchey-Chretien tubes deliver flat-field images with coma virtually absent, excellent for astrophotography! Combing the excellent light gathering power and coma-free images, astrophotographers will render excellent clean and contrast images! Unlike conventional Newtonian reflector and Schmidt-Cassegrain designs that are susceptible to coma away from the center of the field, the Orion 8" Ritchey-Chrétien Astrograph optical tube utilizes hyperbolic primary and secondary mirrors, made of low-expansion quartz glass, to achieve wonderfully flat-field images that are virtually devoid of coma with pinpoint star clarity. Plus, since there are no lenses in an RC telescope, captured images are delightfully free of chromatic aberrations for true-color performance.

  • 8" (200mm) aperture Ritchey-Chrétien optical tube ideal for use with DSLR cameras and small-format CCDs to produce wonderfully flat, virtually coma-free astrophotos
  • Hyperbolic primary and secondary mirrors made of low-expansion quartz glass with enhanced aluminum coatings boast 96% reflectivity for bright imaging performance, and the secondary mirror is precisely center-marked to aid in collimation
  • A rotatable, machined dual-speed (10:1) Crayford focuser equipped with a sturdy linear-bearing provides precise focus adjustment without slippage or flexure with heavy astrophotography accessories attached
  • Three included focus extension rings (one 2" and two 1") allow focus position adjustment for use with various imaging cameras and astrophotography accessories
  • Features two dovetail finder scope bases and a unique, Orion-exclusive slotted narrow dovetail bar along the top of the tube for easy accessory attachment


The enameled steel Orion 8" Ritchey-Chrétien optical tube is fortified with 9 internal, computer-positioned knife-edge light baffles; and both the primary mirror tube and secondary mirror light shield are highly baffled to ensure maximum image contrast for bright images rich in detail. Unlike Schmidt-Cassegrains, the primary mirror of the 8" Ritchey-Chrétien telescope is fixed in-place to eliminate annoying "image shift" that can wreak havoc during imaging sessions. Enhanced aluminum coatings on both the primary and secondary mirrors of the 8" Ritchey-Chrétien Astrograph provide 96% reflectivity with a protective quartz overcoat. Designed with collimation in mind, the secondary mirror of the 8" RC is precisely center-marked to facilitate collimation adjustments should they become necessary.

The Orion 8" RC Astrograph features a machined, dual-speed (10:1) Crayford focuser equipped with a sturdy linear-bearing mechanism for enhanced rigidity and stable support of heavy astrophotography equipment. The rock-solid focuser provides 140.7mm of backfocus travel (238.1mm from the rear cell) to easily accommodate imaging accessory trains, and an engraved millimeter scale on the drawtube enables easy focus point repeatability. One 2" and two 1" machined focus extension rings are included so you can adjust focus position for various imaging cameras and accessories. Two dovetail finder scope bases positioned on either side of the focuser allows easy installation of optional Mini Guide Scopes and aiming devices (sold separately). The 8" Ritchey-Chrétien tips the scales at 18.5 lbs. and is equipped with a narrow "Vixen-style" dovetail bar along its underside for easy attachment to large equatorial mounts. A unique, Orion-exclusive slotted narrow dovetail bar along the top of the telescope allows easy attachment of optional guide scopes and other imaging accessories.



Name Orion - 8" f/8 Ritchey-Chretien Astrograph Telescope
Manufacturer Orion
Model ORI-08267
Diameter 200mm
Finderscope None
Focal Length 1600mm
Focal Ratio f/8.0
Focuser 2" dual-speed linear bearing Crayford
Highest Useful Magnification 236x
Included Accessories Vixen-Style dovetail mounting bar on top, Two dovetail finder scope bases for finder scopes, 1" & 2" Extension tubes
Limiting Stellar Magnitude 14.2
Lowest Useful Magnification 29x
Mount Optical Tube without Mount
Optical Design Ritchey-Chretien
Optical Tube Aluminum
Optical Tube Length 22.0 in.
Optical Tube Weight 18.5 lbs
Resolving Power 0.58arc*sec
Secondary Mirror Obstruction 95mm
Secondary Mirror Obstruction by Area 22%
Secondary Mirror Obstruction by Diameter 47%
Warranty One year


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