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Officina Stellare - Ultra CRC 300 Ritchey Chrètien Telescope Sitall

Model#: UCRC300SITOP

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Manufactured by: Officina Stellare


Officina Stellare Ultra CRC 300 Telescope Sitall

Move over Ritchey Chrètien designers... There's a new kid on the block and its name is Officina Stellare!


The Officina Stellare Ultra CRC 300 telescope is a premier design ultra corrected Ritchey Chrètien telescope that features unique and innovative primary cell design that includes a three fan ventilation system. Its beautiful zero expansion carbon fiber open truss tube body is trimmed with CNC aluminum fittings.


The materials Officinia Stellare uses in their premium quality Ultra CRC 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.


Officina Stellare Ultra CRC 300 TelescopeAll the mechanical parts for the the Ultra CRC 300 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 Ultra CRC 300 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 larger mirror (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 Ultra CRC 300 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 Ultra CRC 300 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 Ultra Corrected Ritchey Chretien is an Officina Stellare exclusive optical scheme. Developed for highest photography performance and the highest efficiency of light transfer to focal plane, with only two hyperbolic mirrors and two spaced elements back group. The  Officina Stellare Ultra CRC Series true carbon fiber/aluminum compound structure is designed and optimized with CAD and computer  support modelling to achieve the best rigidity and lightness. The truss configuration made by using high vacuum production process,  top quality and zero expansion carbon fiber tubes guarantee the greatest focus stability. Only special lightweight aluminum/Ergal alloy, stainless steel and brass metals are used. All parts are full CNC machined to guarantee the best possible precision.


The Ritchey Cretien telescopic design provides superior and excellent elimiation of optical errors. In this design, coma abberation and other distortions are nearly absent. The Ultra CRC telescopes along with the other advancements provided by Officina Stellare such as the outer carbon fiber and aluminum exterior reduce the weight and volume for easier movement and convenience.



Ultra CRC is the achronym of Ultra Corrected Ritchey-Chrétien, the innovative Officina Stellare exclusive, 4 element optical design with fast focal ratio and flat field, representing the latest of many pioneering projects from Officina Stellare.Developed with in mind the highest possible photographic performanceswhile maintaining a high efficiency in transferringlight on the focal plane, the system consists of only two hyperbolic mirrors and a back end two element field corrector. According to the telescope model, the mirrors are produced with either near zero thermal expansion Sitall ceramic glass, or selected low expansion glasses. The corrected and illuminated field covers a diameter of over 60mm, with an outstanding performanceof less than 5 micron (1.0 micron RMS) stars at 30 mm from the optical axis, obtained at the fast F/5.4 focal ratio.


The native fast focal ratio of Ultra CRC astrographs allows to maintain extremely reduced the weight and the overall volume of optical tube.The innovative “double phase” light shield baffle on the secondary mirror is computer optimized with ray-tracing software and allows to eliminate the typical heavy light shield as well to minimize the central obstruction factor, increasing the quantity of light on the focal plane.The Officina Stellare Ultra CRC Series true carbon fiber/aluminum compound structure is designed and optimized with CAD and computer support modelling to achieve the best rigidity and lightness. The truss configuration made by using high vacuum production process, top quality and zero expansion carbon fiber tubes guarantee the greatest focus stability. Only special light weight aluminum/Ergal alloy, stainless steel and brass metals are used. All parts are full CNC machined to guarantee the best possible precision.The high resistance anodization is chosen for unbeatable resistance to environmental conditions. Our unique and innovative design of multipoint axial/radial support primary mirror cell as well the secondary mirror support guarantee absolutely no induced astigmatism on the mirrors and the total absence of mirror shift or flop. A simple to use, single movement operation, efficient and absolutely rock solid collimation system is present. To achieve the perfect collimation is now an extremely simple and immediate process. The Ultra CRC gives the astroimager a high extraction of the focal plane. This guarantees the installation of complex imaging trains, coupling CCD cameras, off-axis guiding systems, adaptive optics, filter wheels, etc., as requested by high level astroimaging tasks. The fastest possible thermal stabilization time is guaranteed, thanks to the mechanical design of the optical tube and to the presenceof three high quality fans.The mechanical design includes a standard four Losmandy dovetail side bars for mount interface and piggy-back guide scopes and/or accessories. Great attention is given to constructive details to complete this masterpiece: computer designed baffles, focal plane tilt adjusting, 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 sensitive parts of the optical path.

Additional Information

Name Officina Stellare - Ultra CRC 300 Ritchey Chrètien Telescope Sitall
Manufacturer Officina Stellare