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GSO 12" Ritchey-Chretien Truss Astrograph Telescope


Please contact us for price and availability.

High quality Ritchey Chretien Astrograph especially designed for astrophotography.

Ritchey-Chretiens deliver images with very little distortion. They have a flat field of view, so objects are in sharp focus right to the edge of the image. The image is coma-free, so stars at the edge of the field of view remain perfectly round. And there is no false colour because they use only mirrors with no correcting lens. 

The 12" f/8 will deliver stunning images, from solar system objects to deep sky nebulae, galaxies and star clusters.  

The primary and secondary mirrors are made of quartz with a low thermal expansion so the telescope keeps sharp focus as it cools down. They are coated with 99% dielectric reflective coating, which gives greater light gathering potential than aluminium coatings. All GSO mirrors are precision engineered and polished to better than 1/12 wavelength, considerably better than the industry norm. Each mirror is individually tested and hand-corrected if necessary after production, with final testing by laser interferometry. 

The carbon fibre truss is exceptionally strong and rigid, ideal for long exposures. The serrurier truss system, originally designed for the 200" Hale telescope, stops flex in the optics with two sets of opposing trusses. This keeps the optical elements in perfect collimation no matter which direction the scope is pointed. 

Losmondy style dovetail plates are fitted top and bottom for attaching to the mount and for accessories to mount onto. 

Ample backfocus allows use of large format CCD cameras, filterwheels, off-axis guiders and rotators.   

Focusing is with a dual speed linear Crayford focuser, so focus is precise. RC scopes also have a fixed primary mirror, with the distance between primary and secondary set precisely at the factory. This eliminates mirror shift issues sometimes encountered with Schmitt-Cassegrain scopes. 

The open tube, quartz mirror and in-built cooling fans enable the telescope to cool quickly, with virtually no problems with dew.

Optical tube assembly only. Comes with a 2" Crayford focuser, two dovetail bars and two 50mm extension tubes. 

This item is not kept in stock. Please contact us for up-to-date pricing.  

Recommended For
What's In the Box?
  • 12" (303 mm) f/8 Ritchey-Chretien optical tube assembly

  • 3" Crayford bearing 10:1 linear bearing micro edge focuser 

  • Losmondy D style wide dovetail mounting top and bottom 

  • 25mm and 50mm extension tube

Optical design Ritchey-Chretien
Primary mirror 12" (303mm) quartz with surface quality better than 1/12 wave RMS
Focal length 2438 mm  
Focal ratio f/8 
Highest practical magnifcation 500x 
Focuser  Crayford 3" bearing 10:1 linear micro edge 
Back focus 288mm from rear cell
Tube length 850 mm 
Tube material Carbon fibre truss
Weight of tube 24 kg 

This product is normally shipped by our freighter service.

Normal delivery is to pickup from their local depot or for delivery to a business address in main towns or cities.

Delivery to a residential address will incur a $45.00 surcharge.

Delivery to a small town or rural address may not be available. We will contact you separately to arrange shipping.