Most large professional telescopes are built according to the Ritchey-Chrétien principle. Until recently, these telescopes were unaffordable for amateurs, but they are becoming increasingly attractive in terms of price.
RC telescopes are ideal for astrophotography. Of course, an RC telescope can also be used for visual observation. Here, too, the large corrected field of view is noticeable.
The advantages of RC telescopes 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 in diameter is also possible without a corrector.
- 99% mirror coating and dielectric coating on the primary and secondary mirrors for an even brighter image.
- Significantly faster cooling time thanks to open design and active primary mirror ventilation.
- Large back focus for correctors, reducers or even binocular attachments
- High-quality 3" MONORAIL focuser with M69x1 threaded connection and 2"/1.25" plug connection.
Astrophotography with the RC telescope:
- Thanks to the large corrected field of view of the RC telescopes, you can take photographs with SLR cameras up to APS-C format without a corrector. For photographs directly in focus, you will need the M117x1 extension tubes, which are included in the scope of delivery. These are screwed between the telescope and the focuser.
- The generous back focus also allows the connection of correctors, which we recommend when using full-frame sensors. You can also connect a focal length reducer to further increase the light intensity of the RC.
- You can clamp the camera directly onto the 2" barrel or screw everything together using the M69x1 internal thread of the focuser.
- The 3" MONORAIL focuser – more than a Crayford: The Monorail focuser combines the smoothness of a Crayford focuser with the rigidity of a rack and pinion focuser. This makes astrophotography a success.
Primary mirror and secondary mirror made of quartz glass with 99% mirror coating and dielectric quartz protective layer: Quartz glass does not change its properties with temperature differences. If the temperature drops slowly during exposure, other mirror materials, such as Pyrex, deform and cause the focus to shift. This problem does not occur with quartz glass mirrors. The focus is therefore maintained better, which is very important for long exposures. Both mirrors are 99% mirrored. The image is visibly brighter than with telescopes with only 90% or 94% mirror coating.
The advantages of RC optics over other systems: Maksutov and Schmidt-Cassegrain optics have spherical mirrors and therefore require downstream optics (correctors) to make a large field usable. Maksutovs are usually so light-faint that they are not suitable for astrophotography. RC telescopes, on the other hand, have hyperbolic primary and secondary mirrors. The RC system is a pure reflection system that does not require lenses in the optical path. This allows photography in the infrared range. The image is brighter and exposure times are shorter. In addition, RC telescopes do not have a dew-prone Schmidt plate on the front.
Carbon Fibre Tube
This apochromat is well suitable to visual observing but was, in fact, developed especially for astrophotography. Use the advantages of a carbon fibre tube: it is particularly light and so even perfectly suitable for using on smaller mounts. The tube also offers a very high inherent stability and only minimal thermal expansion. These advantages are particularly useful for astrophotography, as the focus remains stable for the whole night. The dew shield is also carbon fibre and can be extended easily. In addition, the tube is lined with black felt.
TS Optics is a brand of Teleskop-Service.
