TS-Optics GSO 12 inch f/8 Ritchey-Chretien Astrograph on Skywatcher EQ8 GoTo Mount

Teleskop-Service has optimized this 12" RC especially for astrophotography. The OTA comes with carbon trusses having a thermal expansion of nearly 0. The OTA weight is 24 kg and it has a Losmandy style dovetail rail on both sides.

Our 12" f/8 RC Astrograph illuminates a max. field diameter of approx. 60 mm. Without corrector, 35 mm are possible. In the latter configuration, you have a pure mirror system without any lenses. You don´t need an IR cut filter and can use the full spectrum with a suitable CCD camera.

How to find the focus:
The TS 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 focus point is 127 mm.

To reach the perfect focus position, we suggest the GSRCV1172 und 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 Carbon Fiber Truss Tube Design:

Lightweight yet strong carbon fiber truss tubes have low thermal expansion characteristics. Shifts in focus due to temperature changes are minimized because of this design. The trusses are also designed to flex equally, keeping the optics in collimation regardless of the position of the telescope.




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.

Technical details of the focuser:

Travel: ca. 80 mm

Clear aperture: 68 mm

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

For very heavy cameras, we offer an upgrade to a heavy focuser from Starlight or to the rack and pinion focuser TSFOCR30S from TS Optics.

Astrophotography with the RC telescope:

Due to the large corrected field of view, you can, for example, use a DSLR up to APS-C format without corrector. Thus the RC is a pure mirror system for astrophotography. The images become ultrasharp.

The generous back-focus also allows attaching correctors which we recommend when using sensors of at least full-frame size. You can also attach a focal reducer, thus further increasing the speed of the RC.

Using an SLR without focal reducer: you need a 50 mm and a 25 mm extension tube between focuser and telescope (item # GSRCV50 and GSRCV25).

Using an SLR with focal reducer CCDT67 or CCD47: in this case, a 50 mm extension tube between focuer and telescope (item # GSRCV50) is sufficient.

Optical Highlights:
The hyperbolic primary and hyperbolic secondary are made from low expansion quartz glass, and finished with a 94% enhanced reflectivity for great contrast. The primary mirror is fixed in place in a metal mirror cell, and the secondary resides in a metal housing that can be collimated. The secondary mirror has a center mark for easy and accurate collimation.

Cooling Fans:
The RC telescope has three small cooling fans in the rear cell that help create an ambient temperature within your telescope for more stable viewing and less fluctuation in focus. The fans are powered by an external battery pack. This battery holder accepts 8 AA batteries (sold separately).

A Fixed Primary Eliminates Image Shift:
Schmidt-Cassegrain, EHD, ACF... & Mak-Cassegrain telescopes achieve focus by moving the primary mirror back and forth inside the optical tube assembly, and this movement can cause image shift. While manufacturers have done a pretty good job of minimizing image shift on their telescopes, a moveable mirror makes it almost impossible to eliminate it completely. The Ritchey-Chrétien has a primary that is fixed in place, removing the possibility of image shift and also the job of collimating the primary.

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.

The optical advantages of TS 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.

Video with information about RC telescopes

On our YouTube account you will find a video about the characteristics of the Ritchey-Chrétien telescopes in general and the features of the GSO RCs in particular, as well as suggestions for accessories:

Adjusting the RC telescope

We recommend the TSRCKOLLI or an collimating telescope for adjusting the telescope. These tools are linked in the "Cleaning & Collimating" section.

Instruction video

Teleskop-Service has created an instruction video about collimating an RC telescope:

Important note about power supply:

To avoid loss of warranty, please use only the power supplies and mobile supplies recommended by us. Especially simple car batteries or sealed lead-acid batteries can lead to an under-supply, which can then damage the sensitive electronics of the mount. Operating a Skywatcher GoTo mount with its own power supply is at your own risk. Thank you for your understanding.

Safety informations: PDF Download