Ritchey-Chrétien 10" f/8


10" f/8 true Ritchey-Chrétien hyperbolic mirror optical design
• low thermal expansion quartz primary and secondary mirrors
• 99% reflectivity non-tarnishing dielectric mirror coatings
• high strength/low thermal expansion carbon fiber optical tube
• genuine Feather Touch dual-speed Crayford focuser
• 2" and 1.25" compression ring eyepiece holders
• Losmandy-style “D-plate" dovetail

    True Ritchey-Chrétien telescopes typically start at well over R72 900, putting them out of the reach of most astrophotographers. At least, true R-Cs used to start at R72 900 and up.


    Introducing the GSO GS-RC10, the first affordable large Ritchey-Chrétien!

    The GSO GSRC10 makes the coma-free imaging of a true Ritchey-Chrétien optical system available to the large format CCD astrophotographer at a price less than that of most 35mm-format CCD cameras. Featuring first-quality dielectric mirror coatings (something even the R72 900+ R-Cs typically don’t have), premium low thermal expansion quartz mirrors rather than ordinary optical glass, and a high strength/low thermal expansion carbon fiber optical tube, this economical 10" GSO R-C makes you wonder just what those R72 900+ R-Cs have that makes them cost so much.

    Designed strictly for exceptional imaging, the GSO GS-RC10 provides the wide coma-free photographic field that 35mm film and 35mm-format CCD astrophotographers crave, but can’t get from conventional reflectors and Schmidt-Cassegrains. Likewise, as a pure two-mirror system, the GS-RC8 is totally free from the spurious color that affects the imaging of all but the most costly apochromatic refractors, and it does it with an 8" aperture that dwarfs the light gathering of most apo refractors.

    If serious astrophotography is your goal, but the price of most true Ritchey-Chrétien optics has been keeping you from the optical design most modern professional observatories and the Hubble Space Telescope use for their imaging, your wait is over. The GSO GS-RC10 can bring the world of professional deep space imaging to your backyard observatory at a truly affordable price.

This Astrograph’s Optical System . . .

  • Optical design: true Ritchey-Chrétien Cassegrain-type two-mirror optics, with hyperbolic primary and secondary mirrors.  
  • Aperture: 10", 2250mm focal length, f/9 focal ratio.
  • Primary mirror: Made of low thermal expansion quartz. Polished to 1/12th wave or better surface accuracy. Unlike designs that move the primary mirror fore and aft in the optical tube to focus (which can lead to image shift as the mirror position changes) the GS-RC10 primary mirror is fixed to eliminate image shift and focus changes.
  • Secondary mirror: Made of low thermal expansion quartz. Polished to 1/12th wave or better surface accuracy. Mounted in a four-vane spider and fully collimatable using simple standard Schmidt-Cassegrain collimating techniques. Unlike complicated R-C designs that use motors to move the secondary mirror fore and aft to focus, the GS-RC10 secondary mirror is fixed and focusing is done externally.
  • Dielectric coated optics: Both primary and secondary mirrors have non-tarnishing state-of-the-art dielectric mirror coatings. These have a full 99% reflectivity for the brightest possible images. This is substantially higher than the 88% reflectivity of conventional aluminum coatings or the 94-96% reflectivity of enhanced aluminum coatings.
  • Optical tube: Made of light weight/high strength woven carbon fiber-reinforced composite material with extremely low thermal expansion characteristics to reduce the possibility of temperature-related focus changes. Die-cast and machined aluminum front and rear cells. The carbon fiber tube is virtually indestructible. The use of a carbon fiber composite reduces the weight of the optical tube with no loss of strength or rigidity compared to an aluminum tube. Carbon fiber composites are so strong that the new $200,000,000 Boeing 787 Dreamliner passenger jet will use a wing and fuselage made entirely out of carbon fiber.
  • Internal light baffles: Computer optimized primary and secondary baffling. Nine contrast-enhancing glare-stop baffles in the optical tube, with multiple glare-stop microbaffles in the secondary mirror light shield and primary mirror baffle tube to provide truly dark sky backgrounds during imaging.
  • Dual-speed microfine Feather Touch Crayford focuser: The precision-made non-vignetting focuser is a genuine Feather Touch from Starlight Instruments, a company known world-wide for making the finest and most reliable focusers available to the amateur astronomer. The focuser has dual-speed focusing. There are two coarse focusing knobs. The right knob also has a smaller concentric knob with a 10:1 reduction gear microfine focusing ratio. This provides exceptionally precise image control during critical 35mm or CCD imaging. All focus knobs are ribbed, so they are easy to operate, even while wearing gloves or mittens in cold weather. Multiple internal baffles in the focuser drawtube assure high contrast.
  • Compression ring eyepiece holders: The focuser drawtube ends in a 2" eyepiece holder that uses a non-marring soft brass compression ring to hold 2" imaging accessories in place. The compression ring won’t scratch the barrel of your accessories as an ordinary thumbscrew can. Also supplied is a 1.25" accessory holder that slips into the 2" compression ring holder to let you use 1.25" imaging accessories. Like the 2" eyepiece holder on the eyepiece holder rotation mechanism, the 1.25" adapter also uses a non-marring soft brass compression ring. The 2" accessory holder can be removed from the drawtube to allow the installation of custom A-P type photo accessories available directly from Starlight Instruments.
  • Mounting dovetail: a removable Losmandy-style “D-plate" dovetail runs the length of the underside of the optical tube.
  • Other accessories: A slip-on dust cap is standard.
  • 3" extension tubes.
  • Two year warranty: As an expression of the confidence Telescope shop has in the quality of their products, the GSO GS-RC10 is protected by a two-year limited warranty against flaws in materials and workmanship (shipping case excluded).
  • Model: GS-RC10
  • Shipping Weight: 20lbs
  • 0 Units in Stock
  • Manufactured by: GSO

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This product was added to our catalog on Monday 06 July, 2009.

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