Pro RC 600 ST Ritchey Chrétien 600 mm, F/8 (4800 mm)

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Optical characteristics
The Pro RC Series Ritchey Chrétien telescopes
made by Officina Stellare are built
around the best quality optics today
All optical sets are realized under precise
quality requirement conditions, using the
highest renewed standards in terms of
quality of the materials being used and
the production processes involved.
Each optical set is provided with his own
interferometry report stating and certifying
the overall quality to the customer. In the
making of the optics, we only use blanks
of certified origin and perfect homogeneity.
The materials can be chosen between a
wide range, varying from borosilicate to
Pyrex to Sitall and other low expansion ceramic
type glasses. We offer, as a standard,
very high reflectivity protected aluminizings
and multi layer anti reflex coatings.
It is possible to make special coatings
(silver, gold etc.) for specific wavelength
related needs. We have an in house,
pneumatically insulated, 6 meters long
and 500 Kg weight optical bench using a
Zygo mark IV interferometer with phase
shifter coupled with a highly sophisticated
analysis software for producing extremely
precise measurements and tests. We verify
each and every one of our instruments
before delivery to the final user.
We can also produce real sky tests using
our private observatory with our high capacity
mount and several large format
CCDs in order to match the customer’s
imaging train.
The RC advantages
The advantages of the original Ritchey
Chrétien (RC) optical scheme are very
well known since their introduction. It's the
most diffused optical scheme, adopted
by professionals all over the world. The
Hubble space telescope itself uses the RC
configuration. It is a peculiar variation of
the more classical Cassegrain scheme
that uses only two hyperbolic shaped mirrors.
The use of this aspherical curvature shape,
very difficult to achieve, results in a very
Pro RC 250 ST
Pro RC 320 ST
Pro RC 360 ST
Pro RC 400 ST
Serie Pro RC brochure. v.01/2010
efficient optical system, particularly suited for astrophotography
and professional use. The use of only two optical surfaces
guarantees the minimum possible light loss and the resulting
telescope is “aplanatic” whichmeans coma free (the coma is
one of the most known off ax is optical abberations that
greatly degrades the quality of the images and probably the
most annoying one). The resulting stellar images are particularly
well corrected along the entire illuminated field and the
small residual field curvature (particularly low, thanks to the
smallmultiplier factor of the secondary mirrorwhich is typically
half the factor of the common Schmidt-Cassegrain telescopes)
is easily corrected using custom designed corrector
Sometimes just one lens is enough, and the flatteners are only
needed with the use of very large CCD sensors. Many users
operate the telescopes for imaging without the use of such
correctors. This is obtained with the perfect coupling between
the field of view, the pixel size and the focal length in respect
to the medium viewing conditions.
In such a case, a very well corrected and just reflective telescope
ismore flexible in terms of use, allowing the user to operate
in a more wide range of spectral frequency without
having any chromatic aberration issues. This particular aspect
of the telescope is sometimes determinant in the final decision
for particular research fields.
The Pro RC Series range
Officina Stellare Pro RC Series telescopes cover a very broad
range of needs, from 10 inches (250 mm), to 28 inches (700
mm), but it is possible to built even larger scopes on request.
Apart than these “classical” solutions, Officina Stellare has designed
and built a series of optical add-ons and optical variations
that widen even more the flex ibility of use for the final
The most important of these is certainly the Ultra CRC Series
(Ultra corrected Ritchey Chrétien). It start with a
12,5” (320mm) F/5,4 telescope using two hyperbolic shaped
mirrors and a correcting two elements lens group inside the
rear cell (which is part of the optical scheme and not just a
field corrector) that guarantees the highest level of performance
for wide field photographic applications still maintaining,
not like many other commercial solutions on the market,
the less possible numbers of optical elements in order to max imize
the performance.
The resulting optical performances allow the most prolific use
of the largest available CCD sensors in terms of corrected, illuminated
and flat field and also resolution using small pixels
(the spot size of the telescope is always smaller than the smallest
pixel of the modern CCD's and in the range of 5 microns
over the entire field).
We also offer for our customers a complete series of field flatteners,
with one or two lenses, with three or four inches clear
Serie Pro RC brochure. v.01/2010
diameter, and reducer/corrector groups especially designed
to perfectly match our telescopes. This to guarantee the best
possible flatness of the field while reducing the focal length
increasing the flex ibility of use of the telescopes.
Together with the customer and in order to fulfill his requirements,
Officina Stellare will study the best solutions for optimizing
the imaging train by providing all the parts and components
according to customer needs.
We will also build all the mechanical parts to guarantee the
correct positioning of all components to reach the best possible
optical performances and ease of use.
The materials we use are mostly aluminum and carbon fiber
because of their lightness, their mechanical and thermal properties
and for the optimal resistance to environmental conditions.
We offer to our customers the two classical configuration options
for the OTA, the closed tube (aluminum or carbongraphite
tube) and the most requested carbon-graphite open truss
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 OTA are machined using
CNC computer assisted machines and from a whole block of
aluminum to guarantee the best possible precision. Also the
carbon fiber components are produced following our 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 us to obtain the
best stability of the focus vs temperature changes still maintaining
the best structural rigidity and ligtness.
Design and craftsmanship of O.T.A’s
The designing and structural processes controls are entirely
made with the aid of computer systems in order to max imize
the system efficiency.
The making of all the components and, in particular of the
most critical and precision demanding ones, is done in Italy
directly by us.
All the preliminary, assembly, finishing and quality testing operations
are made in house by us.
Serie Pro RC brochure. v.01/2010
Great 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. After
many tests and designs we finally figured out the best solution
to avoid all the above issues. The primary mirror is fixed in
a multipoint 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 optimalway.
In the largermirror (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 ax ial fans in the back of the cell.
The optical collimation
Great attention has been applied to simplify the collimation
between the mirrors resulting in a stable, efficient but easy to
use system. The collimation is accomplished 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 attention to the details
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 lightshield 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 our telescopes 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.
All our telescopes are built, as required by the most modern
Serie Pro RC brochure. v.01/2010
applications, with a large back-focus length. Compatibility is
guaranteed with the most common accessories on the market
(including focusers, field rotators, AO systems, off-ax is
guides etc.), even with later additions optical systems
(corrector lenses, flattener, reducers etc.).
The open truss, carbon-graphite, structure of our OTAs is designed
for the best rigidity versus weight. Structural tests are
done to ensure resistance and absence of flexure/torsion and
to minimize the transmission and lowering the dumping time of
any vibration. Really advanced design and manufacturing is
adopted for linking the carbon-graphite tubes to the main
aluminum frame. The link is done via spherical heads and receptacles
of centesimal order precision machining. This
method, despite the complexity of the making, guarantees
max imum contact surfaces, precision of positioning and really
easy handling in case any maintenance is required.
The secondary mirror assembly
The front structure of the telescope has to be sturdy enough to
sustain the weight, sometimes quite relevant, of the secondary
mirror and holding system and, eventually, of the precision
motorized moving system for the secondary itself.
For this reason it is been doubled, using a double parallel split
ring for increased stability. The front spider is made using
stainless steel, laser cut, to result in a very solid but of very low
thickness. The spider blades are figured to let the electrical cables
connecting to the secondary mirror to pass through without
obstructing the light path thus minimizing their impact on
the diffraction figure. Each blade is sustained radially by a
special micro metric screw. This system allow us the exact positioning
of the secondary mirror in the center of the sustaining
top ring. This is of crucial importance because the use of
aspherical figured optics implies an unique center of symmetry,
imposing to put the center of the optics to be coincident
to obtain the maximum performances possible and for the
correct use of any optical device to be used in the lightpath.
The holding system of the secondary mirror, in its last revision, is
a small mechanical marvel by itself. Not only the very stable
system holds the mirror in place without introducing any unwanted
tension but it also contains the dew heater for the mirror
and the collimating system that replicates, on a smaller
scale, the same used for the primary. It has been included in
the design a single ax is moving system (manual or motorized)
for back focus adjustments or focusing purposes. Moving the
secondary mirror does not introduce any shift on the focal
plane. The movement is obtained using a linear ball bearing
of great diameter and one, or more, rectified precision bar.
The absolute level of quality of these components guarantees
the least possible focus shift during the mirror movements. The
mirror itself only moves between a fixed range never going out
of the design specs for the optics couple still giving the commodity
of adjusting the back focal length required for the im-
Serie Pro RC brochure. v.01/2010
aging train used. It is possible to adopt our electronic control
system ATC- 02 togetherwith the motorized movement of the
secondary mirror. This option allows the use of a very simple
and useful function that automatically searches for the optimal
positioning of the secondary mirror in order to provide the
optics to work at the figured distance between the primary.
The electric movement of the secondary, if present, is done
via a linear actuator of nanometrical precision for the fastest
and repeatable positioning.
All the mechanical parts are high resistance anodized or multi
layer painted to guarantee inalterable and reliable performance
in time in both performance and appearance. All the
parts that are situated in the optical path are specially
painted to complete opacity and reflex absence.
The RC telescopes from Officina Stellare can be coupled with
different electronic control units entirely designed and made
by us that complete or expand the functionality of the
scopes. The most advanced option available is the Advanced
Telescope Controller 02.
The ATC-02 is a sophisticated microprocessor driven system
entirely made using digital technology that can control all the
possible telescope functions on a local base, via an easy user
interface using few buttons and a large 6” LCD display or on a
remote basis using computer connection.
Basic functions allows stabilization and settings of the mirrors
temperature (using temperature sensors in a closed loop control
configuration), primary mirror fans speed setting, micrometrical
control the movements of the secondary mirror,
automatically re-positioning it to the default (figured by design)
position, monitoring and sensing all the environmental
parameters around the telescope (such temperature, humidity,
air pressure etc.) and so automatically calculating the real
local dew point in order to maintain the mirrors at the lowest
possible temperature to avoid dew formation on the surfaces.
It has a built in precision clock and all the functions and parameters
can be stored in the internal, non volatile memory.
Connected to a PC (the system is fully ASCOM compliant), it
can generate a log file for all the desired parameters to maintain
a “history” record of the working sessions. It is also an
open configuration electronic device” and can be customized
to control several aux iliary devices such electronic focusers
andmore, thanks to the many aux iliary input/output digital
or analog programmable lines presents. One of the most required
options I.e. is the control for the shutters that open or
close the primary mirror of several large telescopes.
Field flatteners/Focal reducers. Electronic, high precision, focusers.
Optical/laser finders. Off ax is guiding scopes. Customized
mounting plates.

  • Model: Pro RC 600 ST
  • Shipping Weight: 369lbs
  • 1 Units in Stock
  • Manufactured by: Officinastellare

This product was added to our catalog on Wednesday 26 May, 2010.

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