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Orion Telescopes
Orion 10" Truss Tube Ritchey-Chretien Astrograph
3 easy payments of $1,066.66
With payment plan
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Expected Ship Date: 10/12/2024

  • 10" (250mm) aperture, f/8 Ritchey-Chretien optics housed in a thermally stable carbon fiber Serrurier-design truss tube assembly
  • Hyperboloid primary and secondary mirrors made of low-expansion quartz glass with 96% reflectivity for bright imaging performance
  • CNC-machined 3.3" dual-speed (10:1) Crayford focuser equipped with a sturdy linear-bearing rail to provide extra support for heavy imaging loads without slippage or flexure; 2" and 1.25" compression ring accessory collars
  • D-style dovetail mounting bars on top and bottom of tube assembly, plus a dovetail finder scope base for attachment of any Orion finder scope (sold separately)
  • Three built-in 1.5" 12V DC-powered cooling fans accelerate equilibration of the primary mirror to ambient temperature

Learn more
Item #  51874

If you have been on the fence about purchasing a Ritchey-Chrétien telescope for astrophotography, you should hop off it now and take a look at the new Orion 10" f/8 Truss Tube Ritchey-Chrétien Astrograph. It features premium quartz mirror optics housed in an ingenious truss tube support structure originally developed back in 1935 for the 200" Hale Telescope at the Palomar Observatory! This exquisitely engineered telescope is optimized for astrophotographic excellence — and will take your imaging pursuits to a whole new level!

Unlike conventional Newtonian reflector and Schmidt-Cassegrain designs that are susceptible to displaying coma away from the center of the field, the Orion 10" f/8 Truss Tube Ritchey-Chrétien Astrograph utilizes hyperbolic primary and secondary mirrors to achieve wonderfully flat images that are virtually coma-free. Plus, since there are no lenses involved, images are delightfully free of chromatic aberration, for true-color performance. Both the 10" (250mm) primary mirror and the secondary mirror are figured from low-expansion quartz glass and boast enhanced aluminum coatings to provide 96% reflectivity. The primary mirror is fixed in place to eliminate annoying "image shift" that plagues Schmidt- and Maksutov-Cassegrain telescopes. The secondary mirror is precisely center-marked to facilitate collimation.

The Serrurier carbon fiber truss system is thermally very stable, minimizing the effect of ambient temperature changes on the telescope's focus. Plus, since it's an open tube, the optics cool down faster than solid tube versions. The Serrurier system utilizes two sets of opposing truss tubes on either side of the declination pivot plane, which keep the optical elements parallel to each other no matter how the telescope is oriented, thus keeping optical collimation precisely intact. Stainless steel ball and socket hardware connects the truss tubes to the telescope's three large CNC-machined aluminum support plates.

The focuser on the Orion 10" f/8 Truss Tube Ritchey-Chrétien Astrograph is a masterpiece of rigidity and precision. The CNC-machined 3.3" dual-speed (10:1) linear bearing Crayford focuser features a stainless steel rail on the drawtube that provides extra support for up to 9 lbs. of imaging gear without flexure or slippage. The focuser can be rotated 360º for image framing. Both 2" and 1.25" non-marring compression ring accessory collars permit the use of 2" or 1.25" accessories. The Orion 10" Truss Tube Ritchey-Chrétien Astrograph has a backfocus distance of 239.8mm, measured from the rear support plate, to easily accommodate imaging accessory trains.

The Orion 10" f/8 Truss Tube Ritchey-Chrétien Astrograph tube assembly is equipped with a D-style dovetail mounting bar on both the bottom and top. A dovetail finder scope base is also installed for attachment of any Orion finder scope or reflex sight (sold separately). Three 1.5" 12V DC cooling fans are mounted on the rear cell to help accelerate optical equilibration to ambient temperature. A battery holder is included (requires eight user-supplied AA batteries), as are one 2" and two 1" threaded extension rings for use in reaching focus with various configurations of imaging cameras and accessories. Primary and secondary mirror dust covers are also provided. Weighing 35 lbs. without any additional accessories, this telescope requires an equatorial mount that can support that load, such as the Orion Atlas Pro AZ/EQ-G or HDX110 EQ-G.

Superb optics, superior design, and sensational affordability come together to make the Orion 10" f/8 Truss Tube Ritchey-Chrétien Astrograph one spectacular instrument for capturing bright, detailed images of deep-space objects with CCD cameras and APS-C and full frame DSLRs. Get yours today!


Limited Warranty against defects in materials or workmanship for one year from date of purchase. This warranty is for the benefit of the original retail purchaser only. For complete warranty details contact us at 800-447-1001.


Please note this product was not designed or intended by the manufacturer for use by a child 12 years of age or younger.

Product Support
Visit our product support section for instruction manuals and more
  • Best for viewing
    Brighter deep sky
  • Best for imaging
    Deep sky
  • User level
  • Optical design
  • Optical diameter
  • Focal length
  • Focal ratio
  • Optics type
  • Glass material
    Low thermal expansion glass
  • Resolving power
  • Lowest useful magnification
  • Highest useful magnification
  • Highest theoretical magnification
  • Limiting stellar magnitude
  • Optical quality
    Diffraction limited
  • Finder scope
  • Focuser
    3" dual-speed linear bearing Crayford
  • Secondary mirror obstruction
  • Secondary mirror obstruction by diameter
  • Secondary mirror obstruction by area
  • Mirror coatings/over-coatings
    Enhanced Aluminum & Silicon Dioxide
  • Mount type
    Optical Tube without Mount
  • Astro-imaging capability
    Lunar, planetary & long exposure
  • Tube material
    Carbon graphite
  • Length of optical tube
    29.5 in.
  • Weight, optical tube
    35.0 lbs.
  • Additional included accessories
    D-style dovetail bars on top and bottom of OTA, Three built-in cooling fans on rear cell, Center-marked secondary mirror for collimation
  • Other features
    One 2" and two 1" extension rings, Primary and secondary mirror covers, Battery holder for fans (requires 8 AA batteries)
  • Warranty
    One year

Truss Tube RC optical tube assembly
2" Extension ring (x1)
1" Extension ring (x2)
Secondary mirror dust cover
Primary mirror dust cover
Battery holder (requires 8 AA batteries, not included)

Orders received by 1pm Eastern Standard Time for in-stock items ship the same business day. Order received after noon will ship the next business day. When an item is not in-stock we will ship it as soon as it becomes available. Typically in-stock items will ship first and backordered items will follow as soon as they are available. You have the option in check out to request that your order ship complete, if you'd prefer.

A per-item shipping charge (in addition to the standard shipping and handling charge) applies to this product due to its size and weight. This charge varies based on the shipping method.

Standard Delivery: $0.00
Standard Delivery to Canada: $300.00
3 Day Delivery: $650.00
2 Day Delivery: $650.00
Next Day Delivery: $750.00

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