Alluna Ritchey-Chrétien Telescopes1 Alluna Ritchey-Chrétien Telescopes2

Alluna Ritchey-Chrétien telescopes
Alluna Ritchey-Chrétien telescopes are professional telescopes and convince with outstanding properties. Ideally suited for astrophotography, even with large CCD cameras, as well as for use in the broad field of astronomical research. The universal usability, stability and compact design with low weight still make Alluna Ritchey-Chrétien telescopes the perfect telescope for schools and public observatories.
Highly accurate optics in a high quality tube, optimized system accessories and intelligent control make Alluna Ritchey-Chrétien telescopes to the reference in this size-class of telescopes. Already today our clients countless installations reliably fulfil their purpose night for night. Our Ritchey Chrétien telescopes are available in sizes 16", 18", 20" and 24 inches.

Alluna RC telescopes - some advantages at a glance

Highest production quality
100% Made in Germany
Reliable and robust
Precision optics
Made by Alluna
Secondary mirror focusing
Robust and
torsion resistant tube
High instrument load possible
(Optional up to 50 kg)
Easy adjustment and absolute
collimation stability
Focus drift compensation
Optimized accessories
for astrophotographers
Robotic main mirror cover
TCS control, including,
ASCOM compatible
Can be remotely controlled

The optic

Alluna Optics has been known for years for excellent optics for reflecting telescopes. In our own manufacturing facility every single RC mirror set is manufactured with utmost precision and care as well as quality inspection. We use only optics from our own production. Only in this way have we been able to ensure a consistently high optical and mechanical quality of our telescopes for years. With delivery, each telescope comes with a detailed test certificate including all necessary optical information. 

Ritchey Chretien telescopes / Spot

When properly installed, the Ritchey-Chrétien system is known for its large, coma-free field. Astrophotographers can use our telescopes for making photographs without visible loss of a large field and without corrective lenses. For CCD cameras in full size or greater, we offer a double-lens 4 inch AFFC (Alluna Flat Field Corrector). With this corrector a photographic plane, a free field can be used of 65 mm diameter free of coma and astigmatism. The corrector is optimized from 404 - 1050 nm.

With our three-lens 4 inch AFFR (Alluna Flat Field Reducer), the focal length is reduced from fF8.0 to f6,0. The field free of vignetting with this reducer is 60 mm in diameter and thus still far larger than required for full-frame. More about our RC correctors

The mechanics

Alluna Optics RC telescopesA radio telescope requires not only perfect functionality but also the greatest precision in all mechanical components for proper operation.
Our telescopes meet all the requirements of high-quality telescopes this size and are regarded as a world reference point. You will not find mirror shifting under load variations, collimation problems, wobbly components or protruding screws in our telescopes. Heavy CCD cameras, for example, do not cause a problem. If required, we can build your OTA so that a 50 kg instrument load at the output is possible for very heavy accessories like spectrometers or heavy cameras.
The optical performance, precision, reliability, and the demand for the highest quality are not left to chance in Alluna Ritchey-Chrétien telescopes. We use specifically for construction and design of our systems, the indispensable support of state-of-the-art 3D CAD. Complex parts and assemblies are modelled exactly as required and assembled virtually in advance. Thus, all parts can be optimized in advance, for example, for weight, stability and expansion behaviour. Using the most modern CNC machines for manufacturing, all parts are made from solid aluminium material in an elaborate honeycomb structure. Only in this way can an RC telescope function demonstrating optimal stiffness, resilience and collimation stability in conjunction with low weight. 
instrument connection telescope Image on the left. Three CCD cameras with massive distribution block, total weight 45 kg connected to an Alluna RC20 telescope output.
No problem for our RC telescopes! Everything is fixed, nothing can shake, the telescope collimation remains rigid and collimation stable. Read more in blog
Alluna carbon tube telescope Image on the left. Alluna RC with carbon fibre tube.
Our Carbon Tube Ritchey-Chrétien telescopes are suitable for use under extreme conditions when an open truss system is not suitable. More about Alluna Carbon telescopes

The telescope controls

Alluna Optics Telescope Control SystemTake care of your astroimages or research; the Alluna Telescope Control System (TCS) takes care of the elementary principal functions of the telescope.
First, the climate of the optical tube and the primary mirror, and second the focusing via the secondary mirror. The optional robotic primary mirror cover or instrument rotator and the secondary mirror heater can be switched via the controller. The entire telescope can be controlled from a single piece of PC software. Of course, all ASCOM functions are supported for remote control.

RC telescope control system / Alluna OpticsIn climate mode you receive precise temperature information, the control of the fan is fully automatic, depending on the current delta between ambient and main mirror temperature. In focussing mode the current focus position in digits, mm or inches is shown on the large display of a PC.  The focusing accuracy is at a resolution of 3936 digits per 1 mm, which corresponds to 0.25 µ m/digit on the secondary mirror or 0.0019 mm on the CCD chip!
With the GoTo function you can load stored focus positions automatically both quickly and accurately. The so-called focus drift can be compensated automatically. The Alluna Telescope Control System has an additional mode of CCD instrument rotator. The includes everything needed for comfortable and precise control; this is an extremely helpful tool for astrophotographers. For a detailed explanation of the functions of the Telescope Control System TCS, please visit the TCS product page

Overview of RC telescopes technical data

Alluna RC16
Alluna RC18
Alluna RC20
Alluna RC24
Primary mirror Ø
415 mm
465 mm
515 mm
610 mm
Optical Ø
405 mm / 16"
455 mm / 18"
505 mm / 20"
600 mm / 24"
Main mirror ap.
f 3,0
f 3,0
f 3,0
f 3,0
System ap.
f 8,0
f 8,0
f 8,0
f 8,0
Secondary mirror Ø
Back Focus
355 mm 
355 mm
355 mm
355 mm
49 kg
60 kg
79 kg
122 kg
RC Field Corrector
corrected field 65 mm
2 lenses 94 mm
Connection M100x1
2 lenses 94 mm
Connection M100x1
2 lenses 94 mmConnection M100x1
2 lenses 94 mm
Connection M100x1
RC Reducer 0,74x
corrected field 60 mm
3 lenses 93 mm
Connection M100x1
3 lenses 93 mm
Connection M100x1
3 lenses 93 mm
Connection M100x1
3 lenses 93 mm
Connection M100x1

Product Video



RC telescopes technical data
Adjustment instructions
Price List RC telescopes & accessories


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