TS - Ritchey Chretien 12" f/8 - Optical Tube - Carbon Truss Tube
The TS 12" f/8 Ritchey Chretien Astrograph is a dream telescope for astrophotography. The telescope is fitted with a stable Carbon Fibre Truss Tube and a precise 3" dual speed Monorail focuser.
The TS 12" f/8 Ritchey Chretien Truss Tube Astrograph is a true RC telescope and will give you spectacular photo results also with large format camera sensors.
The telescope is perfect for small observatories and will be carried from mounts in the EQ8 class.
Optimized for astrophotography
- Aperture 12" / 304 mm
- Focal Length 2432 mm
- Focal Ratio f/8
- Carbon truss tube with 2 Losmandy level dovetail bars
- 99 % dielectric high-reflectivity coating on main and secondary mirror
- Big corrected flat field without need for additional correctors
- 3" Monorail Focuser with better stability
The OTA comes with carbon trusses having a thermal expansion of nearly zero. The OTA weight is 24 kg and it has a Losmandy style dovetail rail on both sides.
The 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 focus
The TS RC has a generous back focus allowing to attach many accessories like off-axis guiders, filterwheels 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 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 Carbon Fibre Truss Tube Design
Lightweight yet strong carbon fibre 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.
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 evenly 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
The hyperbolic primary and hyperbolic secondary are made from low expansion fused quartz, and finished with a scratch-resistant highly reflective 99 % dielectric coating 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.
The RC telescopes 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, and Mak-Cassegrain telescopes achieve focus by moving the primary mirror back and forth inside the optical tube assembly, and this movement can cause image shifts. While manufacturers have done a pretty good job of minimizing image shifts on their telescopes, a moveable mirror makes it almost impossible to eliminate it completely. The Ritchey Chretien 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 EHD or Meade ACF telescopes. These telescopes need a lens corrector which 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 Chretien Astrographs for astrophotography
The TS Astrograph is a real Ritchey Chretien 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.Delivery contents
- 12" f/8 RC Astrograph with Truss Tube
- Losmandy Level Dovetail Rail on Bottom and Top
- 3" Monorail Focuser with Adapter to 2" and 1,25"
High quality 12" Ritchey Chretien by TS with Carbon Fibre Truss Tube.