{"product_id":"orion-optics-uk-odk18tr-optical-tube-assembly","title":"Orion Optics UK ODK18Tr Truss Optical Tube Assembly","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003eOptimized Dall-Kirkham (ODK) Optical Design\u003c\/li\u003e\n\u003cli\u003eOpen Truss Tube Framework\u003c\/li\u003e\n\u003cli\u003ePrimary and Secondary Mirrors by Orion Optics UK\u003c\/li\u003e\n\u003cli\u003eEngineered for Astrophotography\u003c\/li\u003e\n\u003cli\u003eAvailable with Multiple Optical Precision Grades\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c!-- more --\u003e\n\u003cul class=\"tabs\"\u003e\n\u003cli class=\"active\"\u003eDescription\u003c\/li\u003e\n\u003cli\u003eFAQ\u003c\/li\u003e\n\u003cli\u003eSpecifications\u003c\/li\u003e\n\u003cli\u003eIn the Box\u003c\/li\u003e\n\u003cli\u003eWarranty\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cul class=\"tabs-content\"\u003e\n\u003cli class=\"active\"\u003e\n\u003cdiv\u003e\n  \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section-center\"\u003e\n      \u003ch2\u003eOrion Optics UK ODK18Tr Truss Optical Tube Assembly\u003c\/h2\u003e\n      \u003cp\u003eThe Orion Optics UK ODK18Tr is an imaging-first instrument built around the advanced Optimized Dall-Kirkham optical design. Its open truss structure is engineered for rapid thermal equalization and mechanical rigidity, providing a stable platform for demanding astrophotography. This OTA combines a corrected, coma-free field with the meticulous, hand-finished optical quality Orion Optics UK is known for, delivering professional-grade results from a permanent observatory or a portable deep-sky setup.\u003c\/p\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section\"\u003e\n      \u003ch3\u003eThe Optimized Dall-Kirkham Advantage\u003c\/h3\u003e\n      \u003cp\u003eThe ODK18Tr employs an Optimized Dall-Kirkham (ODK) design, a significant advancement over the classical Dall-Kirkham. While the base design uses an elliptical primary and spherical secondary, the ODK incorporates a corrector lens group to eliminate off-axis coma and deliver a flat, sharp field of view. This makes the ODK18Tr exceptionally well-suited for use with modern large-format CMOS and CCD sensors, ensuring point-like stars across the entire frame without the need for an additional external coma corrector.\u003c\/p\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n  \n  \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section\"\u003e\n      \u003ch3\u003eOpen Truss Framework for Thermal Stability\u003c\/h3\u003e\n      \u003cp\u003eUnlike a solid-tube design, the ODK18Tr's open truss framework allows ambient air to circulate freely around the primary mirror. This design minimizes the risk of tube currents and allows the optics to reach thermal equilibrium with the night air much faster. The result is a more stable image, free from the distortions caused by trapped warm air, enabling you to start high-resolution imaging sooner and maintain focus throughout the night.\u003c\/p\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n  \u003cdiv class=\"DAV-bg-light\"\u003e\n    \u003cdiv class=\"DAV-section\"\u003e\n      \u003ch3\u003eOrion Optics UK Hand-Figured Optics: A Choice of Precision Grades\u003c\/h3\u003e\n      \u003cp\u003eAt the heart of every ODK18Tr are primary and secondary mirrors manufactured and hand-figured in the Orion Optics UK workshop. Rather than relying solely on machine polishing, skilled opticians refine each optical surface to an exceptional standard of accuracy. This process allows Orion Optics UK to offer several grades of optical precision, measured in Peak-to-Valley (PV) wavefront error, allowing you to select the level of optical perfection your imaging demands.\u003c\/p\u003e\n      \u003cul\u003e\n        \u003cli\u003e\n\u003cstrong\u003eStandard Optics (1\/4 PV):\u003c\/strong\u003e The minimum grade, offering excellent performance for general deep-sky imaging.\u003c\/li\u003e\n        \u003cli\u003e\n\u003cstrong\u003eProfessional Optics (1\/6 PV):\u003c\/strong\u003e A significant step up, providing higher contrast and sharper detail, ideal for more serious imagers.\u003c\/li\u003e\n        \u003cli\u003e\n\u003cstrong\u003eResearch Grade (1\/8 PV):\u003c\/strong\u003e A premium level of correction that reveals finer planetary detail and resolves tighter star clusters.\u003c\/li\u003e\n        \u003cli\u003e\n\u003cstrong\u003eUltra Grade (1\/10 PV):\u003c\/strong\u003e The highest level of precision offered, for those who require the most accurate and high-contrast images possible from the aperture.\u003c\/li\u003e\n      \u003c\/ul\u003e\n    \u003c\/div\u003e\n  \u003c\/div\u003e\n\n\u003c\/div\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is an Optimized Dall-Kirkham (ODK) and how does the ODK18Tr benefit from it?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eAn \u003cstrong\u003eOptimized Dall-Kirkham (ODK)\u003c\/strong\u003e is a type of Cassegrain telescope that uses an elliptical primary mirror, a spherical secondary mirror, and a small corrector lens group near the focuser. This design corrects for off-axis coma and field curvature, producing a wide, flat, and sharp field of view that is ideal for astrophotography with large sensor cameras.\u003c\/p\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWhat are the advantages of the ODK18Tr's truss tube design?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eThe ODK18Tr's open truss design offers two primary benefits. First, it promotes \u003cstrong\u003erapid thermal acclimation\u003c\/strong\u003e by allowing air to flow freely over the optics, reducing cooldown time and minimizing image-degrading tube currents. Second, a well-designed truss structure provides exceptional \u003cstrong\u003estiffness and rigidity\u003c\/strong\u003e, which helps maintain precise optical alignment regardless of the telescope's orientation.\u003c\/p\u003e\n  \u003c\/div\u003e\n    \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eHow do I choose the right Orion Optics UK optical grade for the ODK18Tr?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eThe choice depends on your primary observing goals and budget.\n      \u003c\/p\u003e\n\u003cul\u003e\n        \u003cli\u003eFor general deep-sky imaging, the \u003cstrong\u003e1\/4 PV Standard\u003c\/strong\u003e optics will deliver excellent results.\u003c\/li\u003e\n        \u003cli\u003eFor those seeking higher contrast and resolving finer details, the \u003cstrong\u003e1\/6 PV Professional\u003c\/strong\u003e grade is a worthwhile upgrade.\u003c\/li\u003e\n        \u003cli\u003eFor planetary imaging or scientific work where maximum resolution is critical, the \u003cstrong\u003e1\/8 PV Research\u003c\/strong\u003e or \u003cstrong\u003e1\/10 PV Ultra\u003c\/strong\u003e grades ensure the highest possible optical performance.\u003c\/li\u003e\n      \u003c\/ul\u003e\n    \n  \u003c\/div\u003e\n    \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eIs the ODK18Tr OTA suitable for visual astronomy?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eWhile the ODK18Tr is optically optimized for imaging, its high-contrast, coma-free views are also superb for visual observation. The large aperture will provide stunning views of deep-sky objects like the Orion Nebula (M42) and distant galaxies, while the high-quality optics will reveal intricate detail on Jupiter and Saturn. Its primary design focus, however, remains astrophotography.\u003c\/p\u003e\n  \u003c\/div\u003e\n    \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eWhat kind of mount is required for the ODK18Tr OTA?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eAn 18-inch truss tube OTA is a large and heavy instrument. It requires a substantial, observatory-class German equatorial mount with a high payload capacity. You should consider mounts from manufacturers like Software Bisque, Astro-Physics, or 10Micron capable of handling the telescope's weight and moment arm to ensure stable, accurate tracking for long-exposure astrophotography.\u003c\/p\u003e\n  \u003c\/div\u003e\n    \u003cdiv class=\"DAV-accordion\"\u003e\n    \u003ch3 class=\"DAV-accordion-Q\"\u003eDoes the open truss design of the ODK18Tr require a light shroud?\u003c\/h3\u003e\n  \u003c\/div\u003e\n  \u003cdiv class=\"DAV-accordion-A\"\u003e\n    \u003cp\u003eYes, for best results, a light shroud is highly recommended. The open truss tube can allow stray light from external sources (like house lights or the moon) to enter the optical path, which can reduce contrast in your images. A fabric light shroud blocks this stray light while still allowing for air circulation, preserving both image contrast and thermal stability.\u003c\/p\u003e\n  \u003c\/div\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n  \u003ctable class=\"DAV-specifications\"\u003e\n    \u003ctbody\u003e\n      \n    \u003c\/tbody\u003e\n  \u003c\/table\u003e\n\u003c\/li\u003e\n\n\u003cli\u003e\n  \u003cul class=\"DAV-grid\"\u003e\n    \n  \u003c\/ul\u003e\n\u003c\/li\u003e\n\n\n\u003cli\u003e\n\u003ca href=\"https:\/\/davidastro.com\/pages\/orion-optics-uk-warranty-policy\" rel=\"noopener\" target=\"_blank\"\u003eOrion Optics UK 1-Year Warranty\u003c\/a\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Orion Optics UK","offers":[{"title":"Default Title","offer_id":52942368637213,"sku":"OOUK-ODK18TR-OPTICAL-TUBE-ASSEMBLY","price":31023.65,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Orion-Optics-UK-Logo_4ecd5251-bae0-4ed8-a630-f69508cd963f.jpg?v=1789606956","url":"https:\/\/davidastro.com\/en-us\/products\/orion-optics-uk-odk18tr-optical-tube-assembly","provider":"David Astro","version":"1.0","type":"link"}