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GSO 12" f/8 Ritchey-Chretien Astrograph with Carbon Fiber Tube

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25.00 kg
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including VAT 20.00 % ( £549.83 )

The TS GSO 12" f/8 Ritchey Chretien Astrograph is a dream telescope for astrophotography. The telescope is fitted with a stable Carbon Fiber tube and a precise 3" M-LRN dual speed Monorail focuser. The GSO 12" f/8 Ritchey-Chretien Carbon Fiber Tube Astrograph is a true RC telescope and will give you spectacular photo results also with full frame format camera sensors. For cameras with a small sensor, particularly most CCD cameras, no field flattener is needed. For cameras with a larger sensor we recommend the use of a field flattening lens. Visual observing is also a highlight with this powerful telescope. The telescope is transportable and will be carried from mounts of the Skywatcher EQ8 class and upwards.

The advantages of the carbon tube are less weight (18kg) and no focus drift, when temperature changes. This is important for astrophotography.


  • Aperture 12" / 304mm
  • Focal Length 2432mm
  • Focal Ratio f/8
  • Carbon fiber tube with 2 Losmandy-type dovetail bars
  • 99% dielectric high-reflectivy coating on main- and secondary mirror
  • Big corrected flat field without need for additional correctors
  • 3" MONORAIL Focuser with better stability


Back focus

The GSO RC has a generous back focus allowing to attach many accessories like off-axis-guiders, filter wheels and much more. The distance from the 2" connection of the focuser to the focal plane is 127mm. To reach the perfect focus position, we suggest the GSRCV1172 and GSRCV1175 extension rings. The position of the rings is between focuser and tube backside. So you always have a good position of the draw tube.

The 3" M-LRN Monorail Focuser:

The 3" Monorail focuser is a further development of the crayford design. The load is not carried by four (often underdimensioned) ball bearings but on a stainless steel track on the base, thus preventing tilting and bending even under high loads. It is countered by a big knurled screw that centers the inner tube exactly to the rail. The load is distributed evely across the rail´s surface.

Specifications of the focuser:

  • Travel: ca. 80mm
  • Free aperture: 68mm
  • Guidance: by massive and fixed steel rail
  • 1:10 transmission for precise focusing
  • 360° Rotation
  • Adaption to 2" and (when screwed off) female M68 thread, directly fitting to TS 2.5" off-axis-guider

TS GSO Ritchey-Chrétien (RC) telescopes are known for their excellent optical performance, especially for photographical applications. But RC telecopes are also well known for their expensive price. Teleskop Service want to change this situation and with the help of GSO we offer a full line of true RC telescopes for the amateur to an affordable price.

Features of the TS GSO RC Telescopes:
♦ True RC Optic with a hyperbolic primary and a hyperbolic secondary mirror
♦ Primary and Secondary mirror are made of low thermal expansion quartz
♦ The Secondary mirror has a center marc for better and more simple collimation
♦ 99% reflectivity non-tarnishing dielectric mirror coatings
♦ Big well corrected flat field without need of a seperate corrector
♦ Enough Backfocus for correctors and reducer
♦ Less dew problems against Schmidt Cassegrain or similar
♦ Fast cooling down time because it is an open system
♦ Each RC is tested and checked on our optical banch

Low Thermal Expansion Quartz Primary and secondary mirrors with 99% reflectivity:
Designed for astro imaging, TS RC mirrors are made of low thermal expansion quartz, rather than the ordinary optical glass used by competitors. Ground and polished under precision computer control to diffraction-limited or better surface accuracy. Both primary and secondary mirrors have a full 99% reflectivity for the brightest possible images. This is substantially higher than the 88% reflectivity of competitors’ conventional aluminum coatings or the 94-96% reflectivity of enhanced aluminum coatings.

The optical advantages of TS GSO RC *Ritchey Chrétien“ Astrographs for astrophotography:
The TS Astrograph is a real Ritchey-Chrétien reflector telescope. Contrary to Maksutovs or Schmidt-Cassegrains which have spherical mirrors and need image correctors, and contrary to Newtonians that need coma correctors, the RC system is a well corrected photographical instrument that uses only mirrors (no false colour!) and does not require any corrector with many cameras.

Why the RC Telescope is better, than Schmidt Cassegrain telescopes with correctors:
This is also the advantage of RC telescopes against Celestron EHC or Meade ACF telescopes. These telescopes needs a lens corrector wich is integrated in the optical system. The RC is a true reflection system without lens corrector and with a really bright image.

TS RC Telescopes – the optical system:
The RC has a concave hyperbolical primary mirror and a convex hyperbolical secondary mirror. The resulting image correction throughout the field as well as the sharpness on the optical axis are superior to typical Schmidt-Cassegrains or Newtonians. Both mirrors are ground and polished under pricision computer control to diffraction-limited or better surface accuracy.

Fixed primary mirror,– no image shifting:
Most similar telescopes have a movable primary mirror cell. When focusing the telescope the entire mirror is moved. Unfortunately this technique invariably leads to a certain amount of image shift. Most manufacturers have controlled this problem to a fair extent, but the remaining image shift can be quite distracting for astro-imaging, particularly with cameras with a small sensor size or when taking series of frames with several hours of total exposure time. In the TS RC the mirror sits in a fixed mirror cell and focus is changed with a separate focuser. This eliminates the problem of image shift completely.

Ritchey-Chretien Telescopes from Teleskop-Service,– why they are so cheap comparing to similar RC telescopes:
Ritchey-Chrétien (RC) telescopes are known for their excellent optical performance, especially for photographical applications. At the same time however RCs were always notorious for being very expensive. To change this Teleskop-Service and "Astro-Tech" asked GSO (Guan Sheng Optics) to produce true RC telescopes. GSO is best known for their excellent Newtonian optics which they have built for many years now. The result of this joint venture is an instrument that is superior in most aspects to a conventional Schmidt-Cassegrain, and still comes at a very affordable price. Teleskop-Service is the European distributor for these instruments from GSO.

Mount Recommendations

You would need a strong, heavy-duty mount to carry the weight of the tube: 18kg + focuser + camera equipment, therefore we suggest the following telescope mounts:

Skywatcher EQ8

Celestron CGEM-DX or CGE PRO

Fornax 52



Box weight: 34kg

Box Size: 111 x 59 x 64 cm (volumetric weight 84kg)

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