Orion 10" f/8 Ritchey-Chretien Astrograph Telescope

About this product

• 10" (250mm) aperture, f/8 Ritchey-Chretien optical tube optimized for astrophotographic use with APS-C and full-frame (35mm) CCD cameras and DSLRs
• Features a big 3.3" rotatable dual-speed (10:1) Crayford focuser equipped with a sturdy linear-bearing to provide fine focus adjustment without slippage or flexure with heavy imaging accessories attached
• 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
• Features two dovetail finder scope bases and a unique, Orion-exclusive slotted wide-format dovetail bar along the top of the telescope for easy attachment of imaging accessories
• Three built-in 1.5" cooling fans accelerate cooling of the primary mirror to reach thermal equilibrium quickly

Go after even the most elusive and faint deep-sky targets with the Orion 10" f/8.0 Ritchey-Chrétien Astrograph. Featuring the highly regarded Ritchey-Chrétien optical design with excellent light gathering, a host of deluxe features, durable construction, and virtually coma-free optics, the big 10" RC is the ideal choice for astrophotographers searching for a superb imaging instrument.

Unlike conventional Newtonian reflector and Schmidt Cassegrain (SCT) designs that are susceptible to displaying coma away from the center of the field, the acclaimed Ritchey-Chrétien design utilizes hyperbolic primary and secondary mirrors to achieve wonderfully flat images that are virtually coma-free with pinpoint star clarity all the way out to the field edge. Plus, since there are no lenses in an "RC" telescope, captured images are delightfully free of chromatic aberrations for true-color performance. Both the primary and secondary mirrors of the Orion 10" RC are made of low-expansion quartz glass and feature enhanced aluminum coatings to provide 96% reflectivity with a protective quartz overcoat. The primary mirror of the Orion 10" Ritchey-Chrétien is fixed in-place to eliminate annoying "image shift" that plague Schmidt-Cassegrain telescopes which can wreak havoc during imaging sessions. The secondary mirror is precisely center-marked to facilitate collimation. The 10" enameled steel optical tube is fortified with 8 internal, computer-positioned, knife-edge light baffles; and both the primary mirror tube and secondary mirror light shield are also highly baffled to ensure maximum image contrast. All these elements come together to make this 10" Ritchey-Chrétien Astrograph an ideal instrument for capturing bright and detailed images of deep-space objects with APS-C and full-frame (35mm) CCD cameras and DSLRs.

The Orion 10" Ritchey-Chrétien Astrograph features a huge, 3.3" dual-speed (10:1) modified Crayford focuser with a sturdy linear track bearing which provides rigid, backlash-free support of hefty imaging cameras and accessories. An engraved millimeter scale on the focuser drawtube allows easy focus point repeatability, and the focuser provides 139.6mm of backfocus travel from the 2" collar (243.9mm from the rear cell) to accommodate imaging accessory trains. 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 telescope focuser allows easy installation of optional finder scopes and aiming devices (sold separately). Three built-in 1.5" DC cooling fans on the rear cell helps accelerate mirror cooldown to save time during imaging sessions. A wide, "Losmandy-style" dovetail bar along the bottom of the telescope makes it easy to couple the 35.3 lb. Ritchey-Chrétien optical tube to heavy-duty equatorial mounts. A unique, Orion-exclusive, slotted wide dovetail bar along the top of the 10" RC facilitates easy attachment of optional guide scopes and other imaging accessories.

• Best for viewing

  Brighter deep sky
• Best for imaging

  Deep sky
• User level

  Advanced
• Optical design

  Ritchey-Chretien
• Optical diameter

  250mm
• Focal length

  2000mm
• Focal ratio

  f/8.0
• Optics type

  Hyperbolic
• Eyepieces

  None
• Resolving power

  0.46arc*sec
• Lowest useful magnification

  36x
• Highest useful magnification

  295x
• Highest theoretical magnification

  500x
• Limiting stellar magnitude

  14.7
• Optical quality

  Diffraction limited
• Finder scope

  None
• Focuser

  3" dual-speed linear bearing Crayford
• Secondary mirror obstruction

  110mm
• Secondary mirror obstruction by diameter

  43%
• Secondary mirror obstruction by area

  19%
• Mount type

  Optical Tube without Mount
• Astro-imaging capability

  Lunar, planetary & long exposure
• Tube material

  Steel
• Length of optical tube

  28.4 in.
• Weight, optical tube

  35.3 lbs.
• Additional included accessories

  Three built-in cooling fans, with battery holder, 1.25" compression ring adapter, 1" & 2" Extension tubes
• Other features

  Losmandy-style dovetail mounting bar on underside, Custom Losmandy-style guidescope mounting bar, Two dovetail finderscope bases