DOME PARTS optical RC telescopes
DOME PARTS optical RC telescopes
Observatory Systems
Observatory Systems 


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Ritchey-Chrétièn telescopes are professional telescopes that convince with outstanding optical properties. These instruments are perfectly suited for astrophotography with large format CCD cameras and as such predistined for a broad field of astronomical research. The universal usability, stability and compact design coupled with low weight also make Alluna Ritchey-Chrétièn 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-Chrétièn telescopes an absolute reference in this "size"-class of telescopes. Our many installations reliably fullfil their purpose, night after night.


DOME PARTS Optical offers a comprehensive range of observatory class Ritchey-Chrétièn telescopes  from 16, 18, 20 to 24 inches.

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You want to know this first......

  RC16 RC18


Primary mirror


465 515 612
Useful aperture 405 455 505 600
Main mirror f f 3.0 f 3.0 f 3.0 f 3.0
System f f 8.0 f 8.0 f 8.0 f 8.0
Secondary mirror 160 175 190 222
Obstruction 43% 43% 42% 41%
Back focus (mirror) 355mm 355mm 355mm 355mm
Useful back focus 250mm 245mm 240mm 230mm
Weight 52kg 62kg 79kg 122kg
Control system TCS-2 TCS-2 TCS-2 TCS-2


5 year


5 year


5 year


5 year



Alluna Optics has been known for years for its excellent mirror optics for all kinds of reflecting telescopes.

In our own manufacturing facility every single RC mirror set is manufactured with utmost precision and care, as well as a comprehensive quality control. We use only mirrors optics from our own production.


Only this way, we are able to ensure a consistently high level of optical and mechanical quality, for all our telescopes. With each delivery your telescope comes with a detailed test certificate, including all necessary optical information. 


When it is properly installed and collimated Ritchey-Chrétièn systems are known for their magnificent, large, coma-free imaging plane.


Astrophotographers can use our telescopes for making photographs without visible loss of a large field and without corrective optics installed.


For full size CCD cameras, or big sensors, we offer a double-lens 4 inch AFFC (Alluna Flat Field Corrector). With this corrector the photographic plane and free field can be used of up to 65 mm diameter, fully coma-free and astigmatism. This corrector is optimized from 404 - 1050 nm.


With our three-lens 4 inch AFFR (Alluna Flat Field Reducer), the focal length is reduced from f8.0 to f6,0. The field that is completely free of vignetting with this reducer, offers 60 mm in diameter. Far larger than required for most full-frame sensors. 


A Cassegrain telescope not only requires perfect optical functionality, but also the greatest precision in all mechanical components for proper operation. 

Our telescopes meet the heaviest demands for high-quality telescopes this size and are regarded as a gold standard.

You will not find any mirror shifting under load variations, collimation problems, wobbly components, or any protruding screws in our telescopes. Heavy CCD cameras do not cause any problems. An optional reinforced backplane is availble for ínstrument loads of up to 50 kg like a spectrometers, or massive cameras.

Superb optical performance, precision, reliability, and a demand for the highest quality are not left to chance in Alluna Ritchey-Chrétièn telescopes. We use  an advanced  "state-of-the-art" 3D-CAD system for construction and design of all our systems.


Complex parts and assemblies are modelled exactly as required and  virtually manufactured in advance. Thus, all parts can be optimized in advance, think of weight, stability and expansion behaviour.


Using the most modern CNC machines for manufacturing, all parts are made out of solid aluminium stock into an elaborate honeycomb structure. Only in this way can a RC telescope function with optimal stiffness, resilience and collimation stability, in conjunction with the lowest possible weight.


A proprietary Telescope-Control-System (TCS) takes care of all basic functions of the the main telescope.

Firstly, there is the cooling of the optical tube and primary mirror,  secondly, the ultra-fine focusing of the secondary mirror system.


The optional robotic main mirror cover, the image-rotator, as well as the secondary mirror heater can be operated via the controller.


In Climate mode, you get accurate temperature information. Control of the three fans is fully automatic, depending on the current delta-T between ambient and main mirror temperature.


In Focus mode, the current focal position is automatically shown graphically on a large display but also the positional values in numbers. The actual useful back-focus is displayd in real time from the back plate in millimeters. The focusing accuracy has a resolution of 2240 positions per mm, which corresponds to 0.446 µm/position on the secondary mirror, or 0.0035 mm on the CCD chip. 

With the GoTo function, you can automatically navigate to stored focal positions, quickly and accurately.


The Telescope Control System can also handle an optional CCD Instrument Rotator

This instrument rotator has a positioning accuracy of 0.01 degrees, rotational speed 5 degrees / second. 

NEW: Check our GreenLine range of ROLL-OFF observatories..!

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