Capture exceptional images of night sky wonders with the Orion 8″ Ritchey-Chrétien Astrograph. This true astrograph is optimized for astrophotographic use with APS-C and 35mm CCD cameras and DSLRs. With several key advantages over Schmidt-Cassegrains and other imaging telescopes, this 8″ Ritchey-Chrétien, or “RC”, is a remarkable telescope that delivers amazing, flat-field images which are virtually coma-free to the edge of the fully illuminated field.
This 8″ (203mm) aperture RC combines the highly regarded Ritchey-Chrétien optical design with excellent light-gathering capability, high-end features, and durable construction to provide astrophotographers with an exceptional instrument at an amazing value. Unlike conventional Newtonian reflector and Schmidt-Cassegrain designs that are susceptible to coma away from the center of the field, the Orion 8″ Ritchey-Chrétien Astrograph optical tube utilizes hyperbolic primary and secondary mirrors, made of low-expansion quartz glass, to achieve wonderfully flat-field images that are virtually devoid of coma with pinpoint star clarity. Plus, since there are no lenses in an RC telescope, captured images are delightfully free of chromatic aberrations for true-color performance.
The enameled steel Orion 8″ Ritchey-Chrétien optical tube is fortified with 9 internal, computer-positioned knife-edge light baffles; and both the primary mirror tube and secondary mirror light shield are highly baffled to ensure maximum image contrast for bright images rich in detail. Unlike Schmidt-Cassegrains, the primary mirror of the 8″ Ritchey-Chrétien telescope is fixed in-place to eliminate annoying “image shift” that can wreak havoc during imaging sessions. Enhanced aluminum coatings on both the primary and secondary mirrors of the 8″ Ritchey-Chrétien Astrograph provide 96% reflectivity with a protective quartz overcoat. Designed with collimation in mind, the secondary mirror of the 8″ RC is precisely center-marked to facilitate collimation adjustments should they become necessary.
The Orion 8″ RC Astrograph features a machined, dual-speed (10:1) Crayford focuser equipped with a sturdy linear-bearing mechanism for enhanced rigidity and stable support of heavy astrophotography equipment. The rock-solid focuser provides 140.7mm of backfocus travel (238.1mm from the rear cell) to easily accommodate imaging accessory trains, and an engraved millimeter scale on the drawtube enables easy focus point repeatability. One 2″ and two 1″ machined focus extension rings are included so you can adjust focus position for various imaging cameras and accessories. Two dovetail finder scope bases positioned on either side of the focuser allows easy installation of optional Mini Guide Scopes and aiming devices (sold separately). The 8″ Ritchey-Chrétien tips the scales at 18.5 lbs. and is equipped with a wide “Losmandy-style” dovetail bar along its underside for easy attachment to large equatorial mounts. A unique, Orion-exclusive slotted narrow dovetail bar along the top of the telescope allows easy attachment of optional guide scopes and other imaging accessories.