Ritchey-Chrétien Astrograph...

For the past several years, Star Instruments has been developing a low-cost alternative to our professional series of Ritchey-Chrétien optics. Our goal was to design a system with as flat a field as possible, no color and a system that could be produced less expensively. With these goals in mind we designed a system using Pyrex mirror blanks, a 50% central obstruction and a short back focus.

The Star Instruments Ritchey-Chrétien Astrograph is the ultimate optical system producing impressive results. When compared to f8 coma-free Schmidt-Cassegrain systems, the RC Astrograph has no color, approximately twice as flat a field, less astigmatism and a faster f ratio – the qualities that advanced astrophotographers have been seeking for deep sky astrophotography. Optics are high quality, diffraction-limited for maximum performance.

Star Instruments

 

The 10RCA has just over a 1 degree FOV when used with a KAF09000 (37mm x 37mm). This 45 minute exposure of M45 was taken by Brad Ehrhorn.

Carbon Truss 10RCA f/7 Ritchey-Chrétien Astrograph...

New RCOS 10RCA Carbon Truss Ritchey-Chrétien Astrograph.

 

10RCA Carbon Truss at the RCOS Robotic Observatory - January 2007.

 

 

10RCA Ritchey-Chrétien Specifications
  • 10 inch Primary Pyrex Blank beveled to a 9.875 inch reflective aperture.
  • Diffraction Limited Ritchey-Chrétien Optical System.
  • Enhanced Aluminum (SiO2/TiO2) overcoat - 96.9% reflectivity.
  • Near Zero Expansion, Carbon Fiber Truss offers; Light Weight and Low Specific Heat Capacity, Stable mirror spacing in changing temperatures, better intrinsic seeing, low cross section or "sail" area in windy conditions, and has easy access to all major components.
  • Truss Base Bolts directly to Mounting Plate.
  • All 6061 Aluminum Components are CNC machined for light weight and fast cool down.
  • CNC Machined Rear Cell and Truss Base bolts directly to mount or mounting plate.
  • Ventilated Truss Base Stiffeners.
  • Precision Secondary Mirror Focuser.
  • Primary mirror baffle with internal knife-edge light stops.
  • Conical Secondary Mirror Light Baffle with mask for O.D. of mirror.
  • Passive Cooling.
  • Shipped fully assembled, collimated, and ready to use.
 Base Price $9,400
Delivery Status  
Focal Length 1735mm
35mm Format Spot Size 17 microns
Total Weight* 42 lbs
System 9.75" f/7
Primary Focal Length  
Back Focus 9" (+/-1")
Useful Back Focus 6.5" (+/-1")
Primary to Secondary Spacing 23"
Secondary Size 5.00"
Primary Hole 2.75"

*As weighed ready for imaging equipped as above including TCC, Servo Secondary Focuser, FIA Adapter Set, three 4.625" Side Dovetail Plates and one 12" Dovetail Mounting Plate.

Options and Accessories:
RCOS Precision Instrument Rotator (PIR). Controlled by the Telescope Command Center.
$2,450
RCOS Telescope Command Center (TCC) Controller - Thermal monitor of primary, secondary and ambient air temperature, includes and controls fans, secondary focus position, secondary dew heater operation, and operation of optional Instrument Rotator . Includes Servo DC motor to electronically operate the secondary focuser.
$1,850

RCOS Custom CNC Machined Losmandy compatible 12 inch dovetail plate for top, bottom, or sides with matching Paramount VersaPlate hole pattern, allows dovetail mounting plate to be bolted to VersaPlate once scope is balanced.
$285

RCOS Side Mounted 4.625 inch Universal Dovetail Plate for top, bottom, or sides with matching Paramount VersaPlate hole pattern, allows dovetail mounting plate to be bolted to VersaPlate once scope is balanced. Also has tapped 1/4 Breadboard Pattern.

$105

Optional Carbon Light Shroud around primary mirror.
$230

Losmandy 90mm (3.5") I.D. removable finder bracket (RDF-90).
$130

Fixed Instruments Adapter Set - 6 piece (FIA).
$300

Mini Borg 45 ED f/6.6 Refractor for Finder Scope (Mini45).
Call
Mini Borg 50 Ach f/5 Refractor for Finder Scope (Mini50).
Call
Borg 77mm ED Refractor for Piggy back Guide Scope, Finder Scope, or Wide Field Imager (77ED).
Call
Borg 100mm ED Refractor F4/F6.4 PH for Piggy back Guide Scope, or Wide Field Imager (100ED).
Call
FSQ-106 by Takahashi (FSQ-106).
Call
RCOS Custom Shipping Crate (Crate 10).
$375
Custom airline style carry case (Thermodyne International).
$TBD

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