welcome to
Telescope-Express
++ a competent team – a specialized dealer ++


Please visit our Onlineshop, here you can find more informationsand much more Richey Cretién Telescopes
For this please visit Telescope-Express.com, then have a look by  telescopes

TS-Optics 6 inch f/9 Ritchey-Chrétien Astrograph - metal tube

The Ritchey-Chrétien telescope offers everything you will expect of a portable instrument for astro-imaging. It is extremely portable and offers a superb image quality also visual observing.

♦ Aperture 6" / 152 mm
♦ Focal Length 1370 mm
♦ Focal Ratio f/9
♦ Metal tube with GP style dovetail bar
♦ 94% dielectric high-reflectivy coating on main and secondary mirror
♦ Big corrected flat field without need for additional correctors
♦ 2" Crayford Focuser, 1:10 dual speed
♦ Computer optimized internal baffle System



How to find the focus of the 6" TS RC:

Photography with DSLR camera: The TS 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 (D)SLR camera with the focuser in a moderate position, you need the following accessories:

- GSRCV50: 50 mm spacer, to be placed between focuser and telescope
- TSFA240: T2 adapter with 40 mm extension

How to reach the focus with 2" diagonal mirror for observing:
If you want to make visual observing, you will need a 35 mm extension tube for a 2" diagonal mirror.

TS Ritchey-Chrétien (RC) telescopes are known for their excellent optical performance, especially for photographical applications. But RC telecopes are also well known for their expensive price. Teleskop Service want to change this situation and with the help of GSO we offer a full line of true RC telescopes for the amateur to an affordable price.

Features of the TS RC Telescopes:
♦ True RC optics with a hyperbolic primary and a hyperbolic secondary mirror
♦ The secondary mirror has a center marc for better and more simple collimation
♦ 94% reflectivity non-tarnishing dielectric mirror coatings
♦ Big well corrected flat field without need of a seperate corrector
♦ Enough back-focus for correctors and reducer
♦ Less dew problems against Schmidt-Cassegrain or similar
♦ Fast cooling down time because it is an open system
♦ Each RC is tested and checked on our optical banch

The optical advantages of TS RC Ritchey-Chrétien Astrographs for astrophotography:
The TS Astrograph is a true Ritchey-Chrétien 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 that uses only mirrors (no false colour!) and does not require any corrector with many cameras.

Why the RC Telescope is better than Schmidt-Cassegrain telescopes with correctors:
This is also the advantage of RC telescopes against Celestron EHC or Meade ACF telescopes. These telescopes needs a lens corrector wich is integrated in the optical system. The RC is a true reflection system without lens corrector and with a really bright image.

TS RC Telescopes – the optical system:
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. Both mirrors are ground and polished under pricision computer control to diffraction-limited or better surface accuracy.

Fixed primary mirror – no shifting:
Most 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.

Ritchey-Chrétien telescopes from Teleskop-Service – why they are so cheap comparing to similar RC telescopes:
Ritchey-Chrétien (RC) telescopes are known for their excellent optical performance, especially for photographical applications. At the same time however RCs were always notorious for being very expensive. To change this, Teleskop-Service and "Astro-Tech" asked GSO (Guan Sheng Optics) to produce true RC telescopes. GSO is best known for their excellent Newtonian optics which they have built for many years now. The result of this joint venture is an instrument that is superior in most aspects to a conventional Schmidt-Cassegrain, and still comes at a very affordable price. Teleskop-Service is European distributor for these instruments from GSO.

Details: