GSO 8" RC
I purchased this scope as a replacement for the Celestron NexStar 8SE. It has the same aperture, but a different optical and mechanical design. Overall it is far more suited to astrophotography, whereas the NexStar is really designed for visual use.
The Ritchey Chrétien design is based around hyperbolic primary and secondary mirrors. Like all telescopes, it's a compromise. In my view, the key benefits are as follows:
- Reduced coma
- Fixed Primary Mirror (does not move during imaging)
- Short tube length (performs better in windy conditions and easier to handle)
- No chromatic aberration (mirror only design)
- Open Tube design / No corrector plate (fast cool down and less dew build up than SCT or Mak-newt)
- ideal Camera location (Easy to balance, fixed hard to back plate and primary / less tube sag)
Disadvantages:
- Field curvature
- Diffraction spikes
- No rear cooling fans on the 8" version
- Requires careful collimation
It is a relatively new product, manufactured by Guan Sheng Optical in Taiwan. The focuser is based around a Hiwin Linear Guideway. So far I have no issues with the focuser.
Specifications:
- Type : Ritchey-Chrétien
- Aperture : 203mm
- Focal Length : 1,625mm
- F number : f/8
- Acquired : September 2009
- Focuser travel : 50mm
- Guideway width : 9.00 mm
Guides
I have moved my guide to collimation here.
I have also developed a disassembly guide here.