Astrograph tube TS GSO Ritchey-Chrétien PRO RC 12" Metal

Astrograph Tube TS GSO Ritchey-Chrétien PRO RC 12" Metal

Telescope Ritchey-Chrétien with a diameter of 304mm (12") and focal length of 2432mm, focal ratio f/8.

Telescopes Ritchey-Chrétien (RC) are known for their fantastic optical performance, especially when focusing on photographic applications. But at the same time, telescopes Ritchey-Chrétien have also been notorious for their really high prices. In an attempt to change this dynamic, the popular manufacturer GSO (Guan Sheng Optical), widely known for its excellent Newton tubes, began manufacturing telescopes Ritchey-Chrétien.

The result of this decision has been the production of an instrument that is superior in many respects to conventional Schmidt-Cassegrain instruments and at a price that can still be considered affordable.

Telescope TS-Optics 12" f/8 RC Ritchey-Chrétien
Most large professional telescopes are built on the RC principle. RC telescopes are primarily intended for amateur astronomers with photographic interests. These RC telescopes are ideal for high-resolution astrophotography. Of course, it is also possible to observe through an RC. Here, too, the large corrected field of view is noticeable. Stars are generally sharper than, for example, in a Schmidt-Cassegrain.

This 12" RC is especially suitable for fixed installation. The complete tube protects the optics from stray light and spray. We recommend a stable mount for the 12" RC, such as the EQ8 or the EQ8 Celestron CGX-L.

The advantages of telescopes TS-Optics RC at a glance:

♦ Hyperbolic primary mirror and secondary mirror for a large, fully corrected field of view.
♦ Astrophotography with camera sensors up to 30 mm diameter is also possible without corrector. For larger sensors, e.g. with full frame size.
♦ 99% mirror and dielectric coating on primary and secondary mirrors for an even brighter image.
♦ Significantly faster cooling time due to the open design and active ventilation of the main mirror.
♦ Large back focus for correctors, reducers or binocular focusing.
♦ High quality 3" MONORAIL focuser with M69x1 threaded connection and 2" / 1.25" plug-in connection.

Astrophotography through the RC telescope:
Due to the large corrected field of view of the RC telescopes it is possible to take pictures with SLR cameras up to APS-C format without corrector. The RC is therefore a pure mirror system for astrophotography. Images become ultra-sharp. Infrared light no longer needs to be blocked, but can be used for imaging. Thus, the exposure time is further reduced.

For directly focused exposures, you will need the M117x1 extension tubes, which are included in delivery. These are threaded between the telescope and the focuser and thus reduce counter-focusing.

The generous back focus also allows the connection of correctors, which we recommend from the use of full-frame sensors. You can also connect a focal reducer to further increase the speed of the RC.

You can attach the camera directly through the 2" receptacle or you can screw everything through the internal M69x1 thread of the focuser. You can find suitable adapters in the accessories section.

The 3" Monorail focuser is much more than just a Crayford

The Monorail focuser combines the smoothness of a Crayford focuser with the rigidity of a rack and pinion focuser. This makes for successful astrophotography.

♦ Solid stainless steel guide rail instead of small ball bearings for greater rigidity.
♦ No more tilting when holding the drag tube.
♦ 360° rotation for optimal object orientation.
♦ Female thread M69x1 for screw adaptations.
♦ 2" and 1.25" compression rings for press fits
♦ 1:10 gear reduction for precise focusing
♦ Motor focus can be easily adapted
♦ Board scale, so that the focus is quickly reset.
♦ Easy to use

Astrophotography through the RC telescope:

Due to the large corrected field of view of the RC telescopes it is possible to take pictures with SLR cameras up to APS-C format without corrector. The RC is therefore a pure mirror system for astrophotography. Images become ultra sharp.

The generous back focus also allows the connection of correctors, which we recommend from the use of full-frame size sensors. You can also connect a focal length reduction to further increase the speed of the CR.

♦ Use of an SLR camera without focal length reduction: 50 mm extension and 25 mm extension between focuser and telescope required (Art. No. GSRCV50 and GSRCV25)

♦ Use of an SLR camera with CCDT67 or CCD47 focal reducer: In this case a 50 mm extension between focuser and telescope is sufficient (Art. No. GSRCV50).

Primary mirror and secondary mirror of fused silica with 99% reflection and protective layer of dielectric quartz:
Quartz glass does not change its properties in the face of temperature differences. If the temperature drops slowly during exposure, other mirror materials, such as Pyrex, will cause the mirror to deform and thus shift focus. This problem does not exist with quartz glass mirrors. Therefore, focus is better maintained, which is very important for long exposures. Both mirrors are 99% mirror. The image is visibly brighter than in telescopes with only 90% or 94% reflectivity.

The advantages of telescopes TS RC for astrophotography:
Telescopes TS RC are true Ritchey-Chrétien telescopes. The Maksutovs and Schmidt-Cassegrains have spherical mirrors and need correctors to be able to use a large field. In the case of the Schmidt-Cassegrains, field errors can even be seen in visual use. Maksutow cassegrains are often so weak that they are not suitable for astrophotography. RC telescopes have hyperbolic main and secondary mirrors. These mirrors are more difficult to manufacture, but offer much greater field sharpness and far fewer field errors.

Why is an RC telescope superior to a Schmidt-Cassegrain with correctors?
Telescopes Celestron EHD or Meade ACFs require a corrector. In addition, these telescopes have a Schmidt plate at the front that is prone to dewarping. The RC system is a purely reflector system without any lens in the beam path. This allows all the light to be used also in the infrared range. The image is brighter and exposure times are shorter. The image field of an RC telescope is, by nature, relatively flat and comma-free.

No displacement problem with RC telescopes TS:
Telescopes with primary mirror focusing often suffer from the "shift" problem. The image shifts when focusing or even jumps. Meade y Celestron now have the problem under control, but the effect is still noticeable. The telescopes TS RC do not have this problem because the primary mirror is fixed. Focusing is performed by a high quality focuser. An additional advantage is the optimal distance between the primary and secondary mirror. This ensures the best possible image. If the primary mirror is shifted towards the secondary mirror, the optimum distance is practically never achieved.

What is delivered with the telescope?

♦ Astrographer TS 12" f/8 RC - with steel tube
♦ Dovetailed dovetail style pleats Losmandy on both sides
♦ Pipe rings with flat connection surfaces on both sides
♦ 3" monorail focuser with 2" and 1.25" reduction
♦ Extension tubes M117 (2x 25 mm and 1x50 mm)

OPTICAL ADVANTAGES OF RITCHEY-CHRÉTIEN ASTROGRAPHS FROM GSO

Optical design: Ritchey-Chrétien True (True RC)

The astrographers GSO Ritchey-Chrétien are true, pure reflecting telescopes. Unlike the Maksutov or Schmidt-Cassegrain systems that have spherical mirrors and therefore need correctors, or the pure newtons that always need a coma corrector, the Ritchey-Chrétien systems are very well corrected by themselves without the use of corrector lenses and that makes them an ideal instrument for astrophotography.

RCs have a concave hyperbolic primary mirror and a convex hyperbolic secondary mirror.

The resulting image is fully corrected over the entire field while achieving an image sharpness on the optical axis far superior to that achieved with a traditional Schmidt-Cassegrain or Newton.

It is for this reason that Ritchey-Chrétien telescopes are very popular for astrophotography. The Ritchey-Chrétien configuration is the most frequently used design for professional telescopes such as the 10-meter Keck telescope in Hawaii or the VLT in Chile. Therefore, GSO puts a Ritchey-Chrétien optical design at the service of amateurs but without needing NASA's budget!!!!

Highly reflective 99% Dielectric Coating

The telescope primary mirror GSO Ritchey-Chrétien 8" is made of Quartz, which, like Zerodur, has virtually zero thermal expansion coefficient, allowing it to offer excellent optical performance as the temperature drops as the night progresses. Both the primary and secondary mirrors have a 99% reflection coefficient and are treated to protect the mirror from scratching and aging. Compared to similar instruments, more effective light collection is achieved.

Each optical kit is verified by the manufacturer

To maintain the optical quality level, each optical kit is checked and corrected by hand after leaving the automated production process. The optical equipment is then verified with a Zygo interferometer.

Technical Specifications:

• Optics: Ritchey-Chrétien RC Optics
• Opening: 304 mm / 12"
• Focal length: 2432 mm
• Focal ratio: f/8
• Resolution: 0.38"
• Reflectivity: 99% reflective dielectric mirror coatings that do not fog up
• Rear focus: 233 mm from the rear, 127 mm from the 2" focuser receptacle
• Connection on the focuser: 2", 1.25" and M69x1 thread (female)
• Tube diameter: 356 mm
• Tube length: 890 mm without focuser - 1010 mm with focuser
• Weight: 20.5 kg
• Total obstruction by the secondary: 150 mm
• Dovetail bars: 2x style Losmandy with tube rings
• Dimensions of transport box: 1150 x 530 x 510 mm (LBH)
• Weight of transport box: 32 kg

Astrograph Tube TS GSO Ritchey-Chrétien PRO RC 12" Metal