6" f/9 RC Astrograph - 152 mm Aperture / 1370 mm Focal LengthRitchey-Crétien telescope for demanding astro imaging and observing - with metal 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 6" f/9 Astrograph
offers everything you will expect of a portable instrument for astro imaging. It is extremely portable and offers a superb image quality.
Since the optical layout of the RC uses no lenses or corrector plates there is no false colour at all. Also you will not need to use an IR cut filter, thus increasing the effective light-gathering power of the instrument.How to reach the right focus position with DSLR or CCD:
The RC has a generous back focus allowing to attach many accessories like e.g. off axis guiders, filter wheels etc. If you want to take photos with a DSLR camera with the focuser in a moderate position, you need extension rings, we can offer you for your system.How to reach the focus with diagonal mirror for observing:
If you want to make visual observing, you will need also an extension tube, we can offer you too.Optical Advantages of the RC AstrographsOptical Design: True Ritchey Crétien / RC
The 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 many cameras.
The RC has a concave hyperbolical primary mirror and a convex hyperbolical secondary mirror.
The 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 Crétien 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
The primary mirror of the 6" RC is made of a very homogenous BK7 blank. 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.Each optical set is tested by the manufacturer
For a constant quality level each optical set is tested and hand corrected after the automatic production with state-of-the-art machinery. Then the optical set is tested with a Zygo interferometer.Mechanical Advantages of the RC AstrographsFixed primary mirror cell and computer optimized baffle system
Most similar telescopes have a movable primary mirror cell. When focusing the telescope the entire mirror is moved. Unfortunately this technique envariably 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 seperate 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
The 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 collimation!Delivery contents:
- 6" f/9 RC Astrograph
- 2" Crayford Focuser with 1 1/4" Adapter
- Vixen style Dovetail Plate
Very compact and light Ritchey Crétien Travelling Astrograph with 6" aperture.