{"product_id":"gso-6-inch-f-9-ritchey-chretien-carbon-ota","title":"GSO 6 Inch F\/9 RITCHEY-CHRETIEN CARBON OTA","description":"\u003ch1 data-path-to-node=\"3\"\u003eGSO 6\" f\/9 Ritchey-Chrétien Carbon Fibre OTA: The Ultimate Deep-Sky Astrograph\u003c\/h1\u003e\n\u003cp data-path-to-node=\"4\"\u003eThe \u003cb data-path-to-node=\"4\" data-index-in-node=\"4\"\u003eGSO 6\" f\/9 Ritchey-Chrétien (RC) Carbon Fibre OTA\u003c\/b\u003e is a specialized, professional-grade telescope engineered specifically for deep-sky astrophotography. Utilizing a true Ritchey-Chrétien optical design—the very same configuration used by the Hubble Space Telescope and major research observatories worldwide—this optical tube assembly (OTA) delivers a flat, coma-free field of view right out of the box, completely eliminating the need for expensive external field correctors.\u003c\/p\u003e\n\u003cp data-path-to-node=\"5\"\u003eBrought to you by \u003cb data-path-to-node=\"5\" data-index-in-node=\"18\"\u003eModern Telescopes\u003c\/b\u003e, India’s largest telescope network, this carbon-fibre variant combines uncompromising optical precision with the thermal stability required for long-exposure imaging under changing nocturnal temperatures.\u003c\/p\u003e\n\u003ch2 data-path-to-node=\"7\"\u003eTechnical Deep-Dive: Why the GSO RC Design Excels\u003c\/h2\u003e\n\u003cp data-path-to-node=\"8\"\u003eUnlike traditional Schmidt-Cassegrain (SCT) or Newtonian designs, the Ritchey-Chrétien configuration is a specialized reflector that addresses the core optical aberrations that plague deep-space imagers.\u003c\/p\u003e\n\u003ch3 data-path-to-node=\"9\"\u003e1. Pure Hyperbolic Optics: Native Coma Correction\u003c\/h3\u003e\n\u003cp data-path-to-node=\"10\"\u003eStandard telescopes suffer from coma, an aberration that distorts stars near the edge of the frame into comet-like shapes. The GSO RC6 utilizes a precisely-figured \u003cb data-path-to-node=\"10\" data-index-in-node=\"164\"\u003econcave hyperbolic primary mirror\u003c\/b\u003e and a \u003cb data-path-to-node=\"10\" data-index-in-node=\"204\"\u003econvex hyperbolic secondary mirror\u003c\/b\u003e. Because both mirrors are hyperbolic, the optical system naturally corrects for spherical aberration and coma across a generous \u003cspan class=\"math-inline\" data-math=\"32\\text{ mm}\" data-index-in-node=\"367\"\u003e$32\\text{ mm}$\u003c\/span\u003e fully-corrected image circle. The result? Pin-point, round stars from the center to the very edge of your dedicated astronomy camera or DSLR sensor.\u003c\/p\u003e\n\u003ch3 data-path-to-node=\"11\"\u003e2. High-Reflectivity Dielectric Mirror Coatings\u003c\/h3\u003e\n\u003cp data-path-to-node=\"12\"\u003eEvery photon matters when capturing light from distant galaxies millions of light-years away. The low-thermal-expansion BK7 glass mirrors are polished to a surface accuracy of \u003cspan class=\"math-inline\" data-math=\"\\frac{1}{12}\\lambda\" data-index-in-node=\"176\"\u003e$\\frac{1}{12}\\lambda$\u003c\/span\u003e PV (Peak-to-Valley) or better. They are then treated with \u003cb data-path-to-node=\"12\" data-index-in-node=\"254\"\u003e95% reflectivity dielectric coatings\u003c\/b\u003e. This ensures maximum light throughput, excellent contrast, and long-term durability against oxidation and degradation.\u003c\/p\u003e\n\u003ch3 data-path-to-node=\"13\"\u003e3. Carbon Fibre Chassis: Zero Thermal Drift\u003c\/h3\u003e\n\u003cp data-path-to-node=\"14\"\u003eMetal optical tubes expand and contract as temperatures drop throughout the night, causing subtle focal shifts that can ruin hours of imaging data. The GSO RC 6\" features a lightweight, high-tensile \u003cb data-path-to-node=\"14\" data-index-in-node=\"199\"\u003ecarbon fibre tube\u003c\/b\u003e. Carbon fibre exhibits a near-zero coefficient of thermal expansion. Once you achieve perfect focus at the beginning of your imaging session, the telescope locks that focus in place all night long, regardless of temperature drops.\u003c\/p\u003e\n\u003ch3 data-path-to-node=\"15\"\u003e4. Native ZWO \u0026amp; QHY EAF Compatibility\u003c\/h3\u003e\n\u003cp data-path-to-node=\"16\"\u003eIn modern astrophotography, automated focusing is essential. The upgraded \u003cb data-path-to-node=\"16\" data-index-in-node=\"74\"\u003e2\" dual-speed 10:1 Crayford focuser\u003c\/b\u003e on this GSO OTA is redesigned for modern workflows. It features native, direct-mounting compatibility for electronic automatic focusers like the \u003cb data-path-to-node=\"16\" data-index-in-node=\"255\"\u003eZWO EAF\u003c\/b\u003e and \u003cb data-path-to-node=\"16\" data-index-in-node=\"267\"\u003eQHY EAF\u003c\/b\u003e without requiring custom 3D-printed brackets or aftermarket modifications.\u003c\/p\u003e\n\u003ch2 data-path-to-node=\"18\"\u003eMechanical Specifications \u0026amp; Back-Focus Architecture\u003c\/h2\u003e\n\u003cp data-path-to-node=\"19\"\u003eAchieving the correct distance between the rear of the telescope and the camera sensor (back-focus) is critical for astrographs. The GSO 6\" RC is designed with a highly flexible mechanical back-focus budget to accommodate filter wheels, off-axis guiders (OAGs), focal reducers, and heavy mono CMOS cameras.\u003c\/p\u003e\n\u003cul data-path-to-node=\"20\"\u003e\n\u003cli\u003e\n\u003cp data-path-to-node=\"20,0,0\"\u003e\u003cb data-path-to-node=\"20,0,0\" data-index-in-node=\"0\"\u003eStandard Focuser Back-Focus:\u003c\/b\u003e \u003cspan class=\"math-inline\" data-math=\"159\\text{ mm}\" data-index-in-node=\"29\"\u003e$159\\text{ mm}$\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp data-path-to-node=\"20,1,0\"\u003e\u003cb data-path-to-node=\"20,1,0\" data-index-in-node=\"0\"\u003eTotal Back-Focus from Rear Cell:\u003c\/b\u003e \u003cspan class=\"math-inline\" data-math=\"254\\text{ mm}\" data-index-in-node=\"33\"\u003e$254\\text{ mm}$\u003c\/span\u003e\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp data-path-to-node=\"21\"\u003eTo facilitate easy camera sensor placement, the OTA ships with a collection of threaded M90 extension rings (\u003cspan class=\"math-inline\" data-math='2 \\times 1\\text{\"}' data-index-in-node=\"109\"\u003e$2 \\times 1\\text{\"}$\u003c\/span\u003e and \u003cspan class=\"math-inline\" data-math='1 \\times 2\\text{\"}' data-index-in-node=\"132\"\u003e$1 \\times 2\\text{\"}$\u003c\/span\u003e). By placing these heavy-duty extension tubes between the telescope body and the focuser, you avoid extending the drawtube too far out, thereby eliminating mechanical sag and tilt in your imaging train.\u003c\/p\u003e\n\u003ch3 data-path-to-node=\"22\"\u003eFull Specifications Table\u003c\/h3\u003e\n\u003ctable data-path-to-node=\"23\"\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eParameter\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cstrong\u003eTechnical Specification\u003c\/strong\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan data-path-to-node=\"23,1,0,0\"\u003e\u003cb data-path-to-node=\"23,1,0,0\" data-index-in-node=\"0\"\u003eOptical Configuration\u003c\/b\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan data-path-to-node=\"23,1,1,0\"\u003eRitchey-Chrétien (RC)\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan data-path-to-node=\"23,2,0,0\"\u003e\u003cb data-path-to-node=\"23,2,0,0\" data-index-in-node=\"0\"\u003eClear Aperture\u003c\/b\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan data-path-to-node=\"23,2,1,0\"\u003e\u003cspan class=\"math-inline\" data-math=\"152.4\\text{ mm}\" data-index-in-node=\"0\"\u003e$152.4\\text{ mm}$\u003c\/span\u003e (6 inches)\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan data-path-to-node=\"23,3,0,0\"\u003e\u003cb data-path-to-node=\"23,3,0,0\" data-index-in-node=\"0\"\u003eFocal Length\u003c\/b\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan data-path-to-node=\"23,3,1,0\"\u003e\u003cspan class=\"math-inline\" data-math=\"1370\\text{ mm}\" data-index-in-node=\"0\"\u003e$1370\\text{ mm}$\u003c\/span\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan data-path-to-node=\"23,4,0,0\"\u003e\u003cb data-path-to-node=\"23,4,0,0\" data-index-in-node=\"0\"\u003eFocal Ratio\u003c\/b\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan data-path-to-node=\"23,4,1,0\"\u003e\u003cspan class=\"math-inline\" data-math=\"f\/9\" data-index-in-node=\"0\"\u003e$f\/9$\u003c\/span\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan data-path-to-node=\"23,5,0,0\"\u003e\u003cb data-path-to-node=\"23,5,0,0\" data-index-in-node=\"0\"\u003eSecondary Mirror Obstruction\u003c\/b\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan data-path-to-node=\"23,5,1,0\"\u003e\u003cspan class=\"math-inline\" data-math=\"76\\text{ mm}\" data-index-in-node=\"0\"\u003e$76\\text{ mm}$\u003c\/span\u003e (\u003cspan class=\"math-inline\" data-math=\"50\\%\" data-index-in-node=\"14\"\u003e$50\\%$\u003c\/span\u003e by diameter, \u003cspan class=\"math-inline\" data-math=\"25\\%\" data-index-in-node=\"32\"\u003e$25\\%$\u003c\/span\u003e by area)\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan data-path-to-node=\"23,6,0,0\"\u003e\u003cb data-path-to-node=\"23,6,0,0\" data-index-in-node=\"0\"\u003eCorrected Image Circle\u003c\/b\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan data-path-to-node=\"23,6,1,0\"\u003e\u003cspan class=\"math-inline\" data-math=\"32\\text{ mm}\" data-index-in-node=\"0\"\u003e$32\\text{ mm}$\u003c\/span\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan data-path-to-node=\"23,7,0,0\"\u003e\u003cb data-path-to-node=\"23,7,0,0\" data-index-in-node=\"0\"\u003eTube Construction\u003c\/b\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan data-path-to-node=\"23,7,1,0\"\u003eUltra-rigid Carbon Fibre\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan data-path-to-node=\"23,8,0,0\"\u003e\u003cb data-path-to-node=\"23,8,0,0\" data-index-in-node=\"0\"\u003eTotal Weight (OTA Only)\u003c\/b\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan data-path-to-node=\"23,8,1,0\"\u003e\u003cspan class=\"math-inline\" data-math=\"5.2\\text{ kg}\" data-index-in-node=\"0\"\u003e$5.2\\text{ kg}$\u003c\/span\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan data-path-to-node=\"23,9,0,0\"\u003e\u003cb data-path-to-node=\"23,9,0,0\" data-index-in-node=\"0\"\u003eTube Dimensions\u003c\/b\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan data-path-to-node=\"23,9,1,0\"\u003e\u003cspan class=\"math-inline\" data-math=\"500\\text{ mm}\" data-index-in-node=\"0\"\u003e$500\\text{ mm}$\u003c\/span\u003e Length (without focuser) × \u003cspan class=\"math-inline\" data-math=\"191\\text{ mm}\" data-index-in-node=\"41\"\u003e$191\\text{ mm}$\u003c\/span\u003e Outer Diameter\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan data-path-to-node=\"23,10,0,0\"\u003e\u003cb data-path-to-node=\"23,10,0,0\" data-index-in-node=\"0\"\u003eMounting Hardware\u003c\/b\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan data-path-to-node=\"23,10,1,0\"\u003ePre-installed Vixen-style Dovetail Bar\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch2 data-path-to-node=\"25\"\u003eWhat’s Included in the Box?\u003c\/h2\u003e\n\u003cul data-path-to-node=\"26\"\u003e\n\u003cli\u003e\n\u003cp data-path-to-node=\"26,0,0\"\u003eGSO 6\" \u003cspan class=\"math-inline\" data-math=\"f\/9\" data-index-in-node=\"7\"\u003e$f\/9$\u003c\/span\u003e Ritchey-Chrétien Carbon Fibre Optical Tube Assembly\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp data-path-to-node=\"26,1,0\"\u003eUpgraded 2\" Dual-Speed 10:1 Crayford Focuser\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp data-path-to-node=\"26,2,0\"\u003e2\" to 1.25\" Step-Down Adapter with brass compression rings\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp data-path-to-node=\"26,3,0\"\u003e2 × 1-inch M90 Threaded Extension Tubes\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp data-path-to-node=\"26,4,0\"\u003e1 × 2-inch M90 Threaded Extension Tube\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp data-path-to-node=\"26,5,0\"\u003eVixen-style Dovetail Rail (attached)\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp data-path-to-node=\"26,6,0\"\u003eQuick-Release Finderscope Bracket\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp data-path-to-node=\"26,7,0\"\u003eFront and Rear Dust Caps\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2 data-path-to-node=\"28\"\u003ePros \u0026amp; Cons for the Astrophotographer\u003c\/h2\u003e\n\u003ch3 data-path-to-node=\"29\"\u003ePros:\u003c\/h3\u003e\n\u003cul data-path-to-node=\"30\"\u003e\n\u003cli\u003e\n\u003cp data-path-to-node=\"30,0,0\"\u003e\u003cb data-path-to-node=\"30,0,0\" data-index-in-node=\"0\"\u003eNo Field Flattener Required:\u003c\/b\u003e Unlike refractors and SCTs, the native design handles aberrations perfectly.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp data-path-to-node=\"30,1,0\"\u003e\u003cb data-path-to-node=\"30,1,0\" data-index-in-node=\"0\"\u003eNo Dew Caps Needed for Primary:\u003c\/b\u003e The primary mirror sits deep inside the closed carbon fibre cell, significantly reducing dew formation compared to open Schmidt-Cassegrain corrector plates.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp data-path-to-node=\"30,2,0\"\u003e\u003cb data-path-to-node=\"30,2,0\" data-index-in-node=\"0\"\u003eNo Mirror Flop:\u003c\/b\u003e The primary mirror is fixed in place, eliminating the annoying \"mirror flop\" focus shift common in traditional moving-mirror SCTs.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp data-path-to-node=\"30,3,0\"\u003e\u003cb data-path-to-node=\"30,3,0\" data-index-in-node=\"0\"\u003eLightweight Rigidity:\u003c\/b\u003e At only \u003cspan class=\"math-inline\" data-math=\"5.2\\text{ kg}\" data-index-in-node=\"30\"\u003e$5.2\\text{ kg}$\u003c\/span\u003e, this OTA runs beautifully on accessible mid-range equatorial mounts (e.g., HEQ5, AM3, AM5, or CEM26).\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3 data-path-to-node=\"31\"\u003eConsiderations:\u003c\/h3\u003e\n\u003cul data-path-to-node=\"32\"\u003e\n\u003cli\u003e\n\u003cp data-path-to-node=\"32,0,0\"\u003e\u003cb data-path-to-node=\"32,0,0\" data-index-in-node=\"0\"\u003eCollimation:\u003c\/b\u003e Like all RC telescopes, optical alignment requires precision. Both the primary and secondary mirrors are adjustable. (Modern Telescopes provides full calibration support).\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp data-path-to-node=\"32,1,0\"\u003e\u003cb data-path-to-node=\"32,1,0\" data-index-in-node=\"0\"\u003eSpeed:\u003c\/b\u003e At \u003cspan class=\"math-inline\" data-math=\"f\/9\" data-index-in-node=\"10\"\u003e$f\/9$\u003c\/span\u003e, it is a slower optical system ideal for small galaxies, planetary nebulae, and lunar\/planetary imaging. For ultra-wide targets, pair it with a dedicated \u003cspan class=\"math-inline\" data-math=\"0.75\\text{x}\" data-index-in-node=\"168\"\u003e$0.75\\text{x}$\u003c\/span\u003e or \u003cspan class=\"math-inline\" data-math=\"0.67\\text{x}\" data-index-in-node=\"184\"\u003e$0.67\\text{x}$\u003c\/span\u003e focal reducer.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch2 data-path-to-node=\"34\"\u003eWhy Buy from Modern Telescopes India?\u003c\/h2\u003e\n\u003cp data-path-to-node=\"35\"\u003eAs India's premier and largest network for astronomy gear, \u003cb data-path-to-node=\"35\" data-index-in-node=\"59\"\u003eModern Telescopes\u003c\/b\u003e ensures that your high-end optical equipment arrives safely. Every GSO OTA undergoes a rigorous quality check and visual inspection before dispatch. Our dedicated post-purchase technical support team is composed of seasoned astrophotographers who can guide you through collimation, back-focus calculations, and electronic integration to get you imaging your first target flawlessly.\u003c\/p\u003e","brand":"GSO","offers":[{"title":"Default Title","offer_id":43325376135229,"sku":null,"price":56600.0,"currency_code":"INR","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0623\/6595\/8205\/files\/rc6_carbob.jpg?v=1783279435","url":"https:\/\/moderntelescopes.net\/products\/gso-6-inch-f-9-ritchey-chretien-carbon-ota","provider":"Modern Telescopes","version":"1.0","type":"link"}