12" f/8 RC Astrograph - 304 mm aperture / 2432 mm focal lengthRitchey Chrétien telescope for high-level astrophotography with 3" Monorail focuser
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 TS 12" RC f/8 Astrograph
can illuminate a field diameter of max. ca. 60 mm (including optional RC corrector). Without corrector, the useable field has ca. 35 mm diameter. Here, you have a pure mirror system, that can be used without UV/IR cut filter. Most of the CCD cameras are sensitive in this spectral range.
The image is absolutely free from chromatic aberrations and the resolution is higher than most apochromatic refractors in this price range.The RC12´s three-inch mono rail focuser
The 3" mono rail 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.Optical Advantages of the TS RC AstrographsOptical Design: True Ritchey Chrétien / RC
TheTS Astrograph is a real Ritchey Crétien 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 hat uses
only mirrors (no false colour!) and does not require any corrector with
The RC has a concave hyperbolic primary mirror and a convex hyperbolic secondary mirror.
resulting image correction throughout the field as well as the
sharpness on the optical axis are superior to typical
Schmidt-Cassegrains or Newtonians.
It is for this reason that the
Ritchey Chrétien is very popular for astro imaging. The RC optical
system (and a variant of the RC) is the most frequently used design for
professional telescopes such as the 10 meter Keck telescope on Hawaii,
or the VLT in Chile. Finally the RC is also available for amateurs
without a "Nasa budget".99% Dielectric High Reflectivity Coating
primary mirror of the 12" RC is made of quartz which, similar to Zerodur, has practically zero thermal expansion for excellent optical properties during cool-down.
Both primary and secondary feature a 99% high reflectivity coating which
is well protected against scratches and against aging. Compared with
similar instruments you get a much higher effective light gathering
power.Mechanical Advantages of the TS RC AstrographsFixed primary mirror cell and computer optimized baffle system
similar telescopes have a movable primary mirror cell. When focusing
the telescope the entire mirror is moved. Unfortunately this technique invariably leads to a certain amount of image shift. Most manufacturers
have controlled this problem to a fair extent, but the remaining image
shift can be quite distracting for astro imaging, particularly with
cameras with a small sensor size or when taking series of frames with several hours of total exposure time.
In the TS RC the mirror
sits in a fixed mirror cell and focus is changed with a separate
focuser. This eliminates the problem of image shift completely.
Computer optimized baffles are placed inside the tube in order to eliminate stray light.Collimation of the secondary mirror
primary mirror is fixed in its precisely machined mirror cell.
Collimation of the telescope is done through the secondary mirror.
Collimation is rather easy and can even be done by an inexperienced
amateur astronomer - we do however recommend to take your time with the
- 12" f/8 RC Astrograph
- 3" Crayford Focuser with 2" and 1 1/4" Adapter
- Tube Rings with flat support surfaces on both sides
- Losmandy style Dovetail Plate
Powerful 12" Ritchey Chrétien with Quartz Optics.