{"product_id":"orion-optics-uk-odk16tr-optical-tube-assembly","title":"Orion Optics UK ODK16Tr Truss Optical Tube Assembly","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e400mm (16\") Optimized Dall-Kirkham Optics\u003c\/li\u003e\n\u003cli\u003e2720mm Focal Length (f\/6.8)\u003c\/li\u003e\n\u003cli\u003e\u0026gt;52mm Fully Corrected and Illuminated Image Circle\u003c\/li\u003e\n\u003cli\u003e2.4µm On-Axis Spot Size\u003c\/li\u003e\n\u003cli\u003eCarbon Fibre Sandwich Truss Tube Construction\u003c\/li\u003e\n\u003cli\u003e3\" Crayford Focuser with 10:1 Reduction\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\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 ODK16Tr Truss Optical Tube Assembly\u003c\/h2\u003e\n\u003cp\u003eThe Orion Optics UK ODK16Tr is an observatory-class astrograph, combining a 400mm primary mirror with a fast f\/6.8 focal ratio to deliver professional imaging results. Its 3-lens corrector illuminates a flat field greater than 52mm in diameter, producing pinpoint stars with a 2.4µm spot size on-axis and 6.0µm at the field edge. The entire optical system is housed in a thermally stable carbon fibre sandwich truss tube weighing approximately 36kg and supported by a robust 3\" Crayford focuser.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eODK16Tr: A 400mm f\/6.8 Corrected Dall-Kirkham Astrograph\u003c\/h3\u003e\n\u003cp\u003eThe ODK16Tr's optical design starts with a 400mm primary mirror in an optimized Dall-Kirkham configuration, which uses an elliptical primary and a spherical secondary. This combination is precisely figured in-house by Orion Optics UK's master opticians. To eliminate the off-axis coma inherent in the standard DK design, a dedicated multi-coated 3-lens corrector is permanently installed, creating a coma-free, flat-field instrument with a 2720mm focal length.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eA \u0026gt;52mm Flat Field with 2.4µm On-Axis Spots\u003c\/h3\u003e\n\u003cp\u003eThis instrument is engineered for large-format sensors. The optical system produces a fully illuminated and corrected image circle greater than 52mm, comfortably covering full-frame (43mm diagonal) and many medium-format astrophotography cameras. The correction is exceptional, delivering an incredibly tight 2.4µm spot size on-axis and maintaining 6.0µm spots at the extreme edge of the field, ensuring that every pixel on your large sensor captures a sharp, aberration-free star.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eCarbon Fibre Truss and 3-Fan Cooling\u003c\/h3\u003e\n\u003cp\u003eMechanical and thermal stability are critical at this scale. The ODK16Tr uses a carbon fibre sandwich material for its truss tube, which offers superior stiffness and a near-zero coefficient of thermal expansion to hold focus through temperature changes. The open truss design, weighing approximately 36kg, allows the 400mm primary mirror to acclimate rapidly, a process accelerated by three controllable cooling fans integrated into the CNC-machined honeycomb mirror cell. For maximum contrast, an optional light shroud is recommended to block stray light.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003e3\" Crayford Focuser and 216mm of Back Focus\u003c\/h3\u003e\n\u003cp\u003eThe imaging train is anchored by a heavy-duty 3\" Crayford focuser with a 10:1 fine-adjustment knob, capable of supporting large cameras, filter wheels, and off-axis guiders without flexure. The system provides a generous 216mm of back focal distance measured from the rear of the mirror cell. This ample spacing gives you complete flexibility to configure your ideal imaging setup with rotators, adaptive optics, and other accessories while still reaching perfect focus.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eODK16Tr vs. Ritchey-Chrétien: Field Correction and Spot Size\u003c\/h3\u003e\n\u003cp\u003eWhile the Ritchey-Chrétien (RC) is a common choice for two-mirror astrographs, the corrected Dall-Kirkham offers distinct advantages. An RC naturally corrects for coma but leaves off-axis astigmatism, which can elongate stars at the edge of the field. The ODK16Tr's integrated 3-lens corrector is specifically designed to eliminate both coma and astigmatism, resulting in rounder stars and smaller spot sizes across its entire \u0026gt;52mm field of view. This design delivers a higher level of performance for imagers using the largest available sensors.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat size camera sensor can the ODK16Tr fully illuminate?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe ODK16Tr is designed to fully illuminate and correct an image circle \u003cstrong\u003egreater than 52mm\u003c\/strong\u003e in diameter. This comfortably covers professional full-frame sensors (e.g., Sony IMX455, 43mm diagonal) and even larger medium-format sensors like the KAF-16803 (39mm diagonal) with no vignetting from the optical system.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat class of mount is required for the ODK16Tr OTA?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eWith a tube weight of approximately \u003cstrong\u003e36kg (around 80 lbs)\u003c\/strong\u003e before adding a camera and accessories, the ODK16Tr requires a high-capacity, observatory-grade equatorial mount. Look for mounts with a specified instrument capacity of at least 100-120 lbs (45-55 kg) to ensure stability for long-exposure imaging.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the ODK16Tr's design help maintain focus during temperature drops?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe ODK16Tr uses a \u003cstrong\u003ecarbon fibre sandwich\u003c\/strong\u003e material for its truss tube. Carbon fibre has an extremely low coefficient of thermal expansion, meaning it does not shrink or expand significantly as temperatures change overnight. This keeps the distance between the primary and secondary mirrors constant, preventing focus shift and ensuring sharp images throughout your session.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the ODK16Tr's f\/6.8 focal ratio suitable for imaging faint nebulae like the Veil Nebula (NGC 6960)?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, absolutely. While f\/6.8 is not as \"fast\" as some dedicated wide-field refractors, the ODK16Tr's massive \u003cstrong\u003e400mm aperture\u003c\/strong\u003e gathers a tremendous amount of light. This light-gathering power makes it highly effective for narrowband imaging of faint emission nebulae, resolving fine filamentary details in targets like the Veil Nebula or the Cygnus Loop with impressive signal-to-noise ratios.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow will the ODK16Tr's 2720mm focal length frame a target like the Andromeda Galaxy (M31)?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe \u003cstrong\u003e2720mm focal length\u003c\/strong\u003e provides a high-magnification view ideal for detailed studies of smaller deep-sky objects or for creating mosaics of large ones. A full-frame camera on the ODK16Tr would frame the bright core of the Andromeda Galaxy (M31) in incredible detail, resolving individual dust lanes and star-forming regions, but it would not capture the entire 3-degree span of the galaxy in a single shot.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eDo I need to add a light shroud to the ODK16Tr's truss tube?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eYes, a light shroud is highly recommended. The open truss design promotes rapid cooling but is susceptible to stray light from external sources and can be more prone to dew formation on the secondary mirror. A fabric light shroud will significantly improve image contrast by creating a dark interior and will also help protect the optics from dew.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003ctable class=\"DAV-specifications\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003ePrimary Mirror Diameter\u003c\/td\u003e\n\u003ctd\u003e400mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocal Length\u003c\/td\u003e\n\u003ctd\u003e2720mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/6.8\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCorrector Design\u003c\/td\u003e\n\u003ctd\u003eMulti-coated 3 lens\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFlat Field Size\u003c\/td\u003e\n\u003ctd\u003e\u0026gt;52mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpot Size on Axis\u003c\/td\u003e\n\u003ctd\u003e2.4μm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpot Size at Field Edge\u003c\/td\u003e\n\u003ctd\u003e6.0μm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSecondary Mirror Size\u003c\/td\u003e\n\u003ctd\u003e152mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBack Focal Distance\u003c\/td\u003e\n\u003ctd\u003e216mm (from rear of mirror cell, ±1mm)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocuser\u003c\/td\u003e\n\u003ctd\u003e3\" Crayford with 10:1 reduction\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTube Material\u003c\/td\u003e\n\u003ctd\u003eCarbon fibre sandwich\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTube Length\u003c\/td\u003e\n\u003ctd\u003e820mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTube Diameter\u003c\/td\u003e\n\u003ctd\u003e450mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTube Weight\u003c\/td\u003e\n\u003ctd\u003eapprox. 36kg\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMirror Cell\u003c\/td\u003e\n\u003ctd\u003eHoneycomb CNC machined aluminium\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMirror \u0026amp; Tube Cooling\u003c\/td\u003e\n\u003ctd\u003e3 controllable fans, heaters optional\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAttachment Method\u003c\/td\u003e\n\u003ctd\u003eCNC machined aluminium dovetail with supports\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cul class=\"DAV-grid\"\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eODK16Tr Truss Optical Tube Assembly\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\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":52942368145693,"sku":"OOUK-ODK16TR-OPTICAL-TUBE-ASSEMBLY","price":19926.65,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Orion-Optics-UK-Logo_689b3e0d-88fa-4a57-8d85-797329a5a5a8.jpg?v=1789606948","url":"https:\/\/davidastro.com\/fr-us\/products\/orion-optics-uk-odk16tr-optical-tube-assembly","provider":"David Astro","version":"1.0","type":"link"}