TS-Optics 8" f/8 RC Ritchey-Chrétien Telescope with Carbon Tube
Most large professional telescope are constructed according to the RC principle. Until recently, these telescopes were unaffordable for amateurs. RC telescopes from Teleskop-Service are primarily aimed to amateur astronomers with photographic interest. These telescopes are perfectly suited for high-resolution astrophotography. Of course, an RC can also be used for visual observing. Here, the large corrected field of view is noticeable, too. In total, the stars are sharper than, for example, in a Schmidt-Cassegrain.
The advantages of the TS-Optics RC Telescopes at a glance:
♦ Hyperbolic primary and secondary mirror for a large fully illuminated field of view.
♦ Astrophotography with camera sensors up to 30 mm diameter possible without corrector. For larger sensors, like full-frame size, Teleskop-Service offers ready-to-use corrector solutions.
♦ 99% dielectric high-reflectivity coating on main and secondary mirror for an even brighter image.
♦ Significantly shorter cooling down time through open construction
♦ Internal baffles in the tube for even more contrast.
♦ High back focus for correctors, reducers and also binoviewers.
Astrophotography with the TS-Optics 8" RC telescope:
Better and sharper astrophotos without corrector with shorter exposure times. This is exactly what this RC telescope allows you to do with astro cameras and SLRs up to APS-C sensors. As a pure mirror system, you can even use the infrared light. You can achieve up to 25% shorter exposure times and sharper imaging than, for example, through a comparable Schmidt-Cassegrain telescope. For the use of a reflex camera without focal length reduction you need the 50mm and the 25mm extension between focuser and telescope.
The generous backfocus also allows the connection of correctors, which we recommend from the use of full-frame sensors. You can also connect a focal length reducer, thus further increasing the light intensity of the RC.
0.67x CCD reducer for astrophotography
The CCD47 improves the focal ratio from f/8 to f/5.36, thus reducing the exposure time to less than 50%. With this, you can capture dim nebulae and galaxies with moderate exposure times.
The advantages of a carbon tube over a metal tube:
The weight reduction is minimal - only about 300 grams - the main advantage ist the focus stability when temperature changes. That is important for astrophotography. When temperatures drop, metal contracts and the focus moves. Refocusing is necessary. A carbon tube does not change, the combination of quartz glass mirror and carbon composite tube makes a readjustment of the sharpness obsolete, even for long time exposures.
The 2" MONORAIL focuser - more than a Crayford:
The Monorail focuser combines the ease of movement of a Crayford focuser with the stiffness of a rack-and-pinion focuser. Thus astrophotography becomes a success.
♦ Massive stainless steel bar instead of small ball bearings for more stiffness.
♦ No tilting anymore when locking the drawtube.
♦ 360° rotation for optimal object alignment
♦ Female M69x1 thread for threaded adaptions
♦ 2" and 1.25" compression rings for push adaptions
♦ 1:10 dual speed for accurate focusing
♦ Motor focus can easily retrofitted
♦ Lined scale for quick retrieving of the focus.
♦ Easy operation
Primary and secondary mirror of quartz glass with 99% reflectivity and protective dielectrical quarz layer:
Quartz glass does not change its dimensions if temperature changes. When the temperature changes slowly during an exposure, other mirror substrates, like Pyrex, tend to a deformation of the mirror and thus to a shift of the focus. This problem does not exist for mirrors of quartz glass. Thus the focus is better maintained which is very important for long exposures. Both mirrors are coated with 99% reflectivity. The image is obviously brighter than the one of telescopes with only 90% or 94% reflection layer.
The advantages of TS RC telescopes for astrophotography:
The TS RC astrographs are true Ritchey-Chrétien telescopes. Maksutovs and Schmidt-Cassegrains have spherical mirrors and need correctors for making a large field usable. With Schmidt-Cassegrains, you can see the aberrations in the field even when working visually. Most times, Maksutov-Cassegrains are so slow that they are not suitable for astrophotography. RC telescopes have hyperbolical primary and secondary mirrors. They are more difficult to manufacture, but offer a significantly sharper field with less aberrations throughout the field.
Why is the RC Telescope superior to Schmidt-Cassegrain telescopes with correctors:
Celestron EHD or Meade ACF telescopes need a corrector. Additionally, these telescopes have a Schmidt plate at the front side which is prone to dew. The RC is a pure reflection system without lenses in the light path. Thus you can use the complete light even in the infrared range. The image is brighter and the exposure times get shorter. The field of an RC telescope is coma-free by design and relatively flat.
No shifting problem with TS RC telescopes:
Telescopes with focusing via movable primary mirror often suffer from the "shifting problem". The image shifts while focusing or even jumps. By now, Meade and Celestron have the problem under control, but the effect is noticable nonetheless. TS RC telescopes do not have this problem, as their primary mirror is fixed. Focusing is done via a high-quality focuser. An additional advantage is the optimal distance from primary to secondary mirror. This gives you the guarantee of the best possible image. If the primary mirror moves relatively to the secondary, you will practically never have the optimal distance.
Instruction video
Teleskop-Service has created an instruction video about collimating an RC telescope:
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Astrophotos through the TS 8" RC:
♦ M27 - C. Frere
♦ Cameras: Atik383L+ for H-Alpha and O-III
♦ Farbe/Color: QHY8L
♦ M20 - Hamish Thava
♦ L-RGB
♦ Camera: Starlight SXVR-H694
♦ Filter: Baader L-RGB
♦ Mount: Skywatcher EQ6 Synscan
♦ NGC891 - Wolfi Ransburg
♦ Camera: ATIK 4000 Mono
♦ no corrector
♦ 12x 12min
♦ Andy Murner
♦ Moon (valley in the moon alps)
♦ DMK Camera from Imaging Source
Wonderful Images from Jorge Garcia through the 8" RCM63 from Rolf Wilmes through the 8" RC♦ ngc891 - S. Muckenhuber
♦ Integration time: 4h (300 second subs)
An 8" RC with carbon tube and UNC V power focuser was used. The mount was an EQ6-R pro. With the relatively low weight of 7.6 kg the mount coped of course easily.
Even mounts in the HEQ5 category are still suitable for use with the 8" RC.
However, due to the relatively long focal length of 1624 mm, we recommend off-axis guiding for this system.
It is no secret that RC systems are very well suited for galaxies or smaller nebulae because of this long focal length. Therefore, NGC891, a well-known edge-on galaxy, was targeted.
Despite a lot of light pollution and moderate seeing, the result is quite good. Many details are visible and the colors look very natural.The latter is of course also due to the fact that this is a mirror-only system.
There are many myths about the adjustment of RC systems. However, with the right adjustment tool and a little practice, this is no problem.
The collimation was done with the TSRCKOLLI. It can be used to adjust the secondary mirror very precisely. The main mirror adjustment also works well with it. For the latter, however, some "fine tuning" may be necessary. The final touch can be made very well on a defocused star.
