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Officina Stellare - Pro RC 250 LT Ritchey-Chrétien Telescope

Model#: PRC250OTA

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Manufactured by: Officina Stellare


Officina Stellare Pro RC 250 Ritchey Chrètien Telescope

The materials Officinia Stellare uses in their premium quality Pro RC Ritchey Chretien telescopes are mostly aluminum and carbon fiber because of their lightness, their mechanical and thermal properties and for the optimal resistance to environmental conditions. Officina Stellare offers to their customers the two classical configuration options for the OTA, the closed tube (aluminum or carbongraphite tube) and the most requested carbon-graphite open truss configuration. In this last case, the combination between the near zero thermal expansion values of the optics (if produced with Sitall or other ceramics) and the carbon-graphite truss of the structure between the two mirrors, guarantees the most stable and fixed position and focus vs temperature variations thus simplifying the imaging operations. 

All the mechanical parts for the the Pro RC 250 OTA telescopes are manufactured and equipped using CNC computer assisted machines and from a whole block of aluminum to guarantee the best possible precision. Officina Stellare also provides carbon fiber components that are produced following strict specification and tolerances. Each part has been computer designed and optimized for the best structural performance, rigidity and lightness. The holding systems for both mirrors, the spider, rings and all the structural components, even the smallest, are CNC machined from a single block of special aluminum (6061/7075, Ergal and Anticorodal), stainless steel, titanium and brass. The tubes are made of true carbon-graphite fiber obtained with the use of high vacuum process, allowing the observor to obtain the best stability of the focus vs temperature changes still maintaining the best structural rigidity and lightness. 

Officina Stellare ensures that superior care is taken in the making of the rear holding cell of the primary mirror. The hyperbolic shaping combined with the diameter and relative weight of the mirror, imposes a very careful study and design for the holding system in order not to introduce any astigmatism, mirror flop or shift in the system. The primary mirror in the Pro RC 250 OTA telescopic model is fixed in a multi-point cell of innovative design that holds it linearly in the center and radially on the borders in order to distribute the weights, for any given position, in an optimal way. In the large rmirror (starting from 16”) we add an extra reinforcing plate in the back of the mirror and even more holding points, up to 27, optimally distributed using computer based optimization methods; this in order to give an even more increased stability factor to the whole system. The entire rear cell for the primary mirror is figured to have the best rigidity/weight ratio and for the fastest possible thermal stabilization between the environment and mirror. The convection and thermal irradiation are greatly improved with the use of three high quality axial fans in the back of the cell. 

One aspect Officina Stellare has implemented and designed in their Pro RC 250 Ritchey Cretien telescope has been to apply to simplify the collimation between the mirrors resulting in a stable, efficient but easy to use system. Officina Stellare has accomplished this by acting on just three points (the minimum required points to generate a single plane) using a special, great diameter preloaded bolts (one for each point). This results in a single hand use, simply turn the bolt left or right to move the mirror back and forth (no more complicated operations using push pull screws and locks) in a very intuitive way. Finding the correct positions is a snap. The mirror borders uses an opaque, circular mask to avoid any undesired light scattering. The light shields for the primary and secondary mirrors are computer designed and optimized to ensure complete illumination of the field still maintaining a complete protection from stray light. Inside the light shields there are also micro baffles that reduces, coupled with an opaque painting of the surfaces, to nearly zero any possible parasite stray light. In some cases and for particular applications, the light shield for the secondary mirror is made using a special layout that maintain the efficiency of the system while reducing the obstruction for the system. The back plate of the Pro RC 250 telescope comes standard with a system for adjusting the planarity of the focal plane in order to compensate for any small misalignment in the imaging train, always unwanted and annoying specially on today’s large CCD cameras. One that is highly recommended is the Apogee U9000 camera with the Kodak KAF-9000 chip.

The Officina Stellare Pro RC 250 LT/ST telescope has a clear aperture of 250mm and operates at a focal length of 2000mm with an f/8 focal ratio. Its mirror system features LK7 optical glass for LT model and Sitall for ST model and an interferometric report can be provided for each and every telescope. The over all length of the Officina Stellare Pro RC 250 LT/ST optical train assembly is 690mm (slightly over 27 inches) and its over all average weight is 18 kg - or 40 pounds with an average tube diameter 400 mm - or just about 16 inches. The spot size for the Officina Stellare Pro RC 250 LT/ST telescope at 26mm from axis with optional flattener is 15 microns. 

 Officina Stellare Product Number: PRC250OTA


The advantages of the Ritchey-Chrétien telescopes are very well known. It’s the most widely used optical scheme by professional astronomers and astroimagers all over the world. The Hubble space telescope itself uses the RC configuration. PRO RCs by Officina Stellare represent a step forward in state of the art professional instruments in the Ritchey Chretien spectrum. The PRO RC 250 design is a four element combination of hyperbolic mirrors and two elements lens system designed by the most experienced optical engineers with the objective of providing outstanding astronomical performances. The use of four optical elements results in a superb optical quality, suited for the most demanding astroimagers and professional use. Maximum light transmission, widest spectral range and a highly corrected large field are the features of the PRO RC design. The telescopic series cover edge to edge even the largest CCD with the smallest spot size available on the market. Without the flattener lens group (which is easily user removable), and thanks to the versatility of the highly corrected hyperbolic design, the professional scan work anyway with an all reflective system, with increased light transmission and the widest possible spectral range. Thanks to its perfect mechanics, superb certified optics, top level accessories line and our superior customer service, we give you the most powerful tool to take images of the sky with unsurpassed quality.



The Officina Stellare PRO RC 250 is built around the best quality true Ritchey-Chrétien optical sets in today's world. All telescopes are provided with their own interferometric report, stating and certifying the overall quality to the customer. Officina Stellare provides ranges from 250 mm (10 inches) to 600 mm (24 inches), and the company offers both low expansion glass or near zero expansion Sitall ceramic glass substrate options, in which they highly recommend.



The Officina Stellare PRO RC 250 carbon fibre/aluminum compound structure is designed and optimized with CAD and computer support modelling to achieve the best rigidity and lightness. Full CNC machined parts to guarantee the best possible precision. Only special aluminum alloy, stainless steel, titanium and brass metals are used. High resistance anodization or multilayer paint for unbeatable resistance to environmental conditions. Unique and innovative design of both primary and secondary mirror holding cells. Absolutely no astigmatism is induced on the mirrors and the absence of mirrorshift or flop is guaranteed. Fastest possible thermal stabilization time, thanks to the mechanical design of cells andto the presence of three high quality fans. Simple to use, efficient and absolutely rock solid collimation system. Officina Stellare also made sure to pay full attention to constructive details: computer designed baffles, focal plane tilt adjusting, large focus extraction, high precision spherical joint in the truss structure, double parallel split ring for the secondary mirror/spider support, radial micrometric adjusting of spider, manual or motorized zero shift secondary mirror movement, special opaque paint for all optical path sensible parts.


Pro RC 250 Main accessories:

AT C-02 Advanced Telescope Controller (6 inches LCD display, full digital mirrors temperature close loop control, fans speed control, dew point, environmental probe, stand alone or PC control, full SCOM compliant, and more) - F/6 reducer/flattener optical groups - Secondary mirror servo focusing system - Focal plane focusers - Primary mirror motorized covering system - Fly and transport cases - Finder scopes - Piggy back supports - Professional customer service for imaging train parts optimization, design and realization.


For extra functionality with added accessories, we recommend the Pro RC 250 Full Package.






Additional Information

Name Officina Stellare - Pro RC 250 LT Ritchey-Chrétien Telescope
Manufacturer Officina Stellare
Model PRC250OTA
Aperture 250mm
Diameter 250mm (10")
Focal Length 2000mm
Focal Ratio f/8
Included Accessories OTA with two elements flattener, two dovetail bars, heater and manual control on both mirrors, manual movement of secondary mirror, black fabric shroud and caps
Length 690mm
Optical Design Ritchey-Chrétien Telescope with Low Exp. or Sitall glass
Optical Tube Carbon truss tube CNC Aluminum
RMS Spot Size 4.0 microns @ 26mm