{"product_id":"orion-optics-uk-ag12-optical-tube-assembly-only","title":"Orion Optics UK AG12 Optical Tube Assembly","description":"\u003cul class=\"DAV-feature-list\"\u003e\n\u003cli\u003e300mm (12\") Primary Mirror\u003c\/li\u003e\n\u003cli\u003e1140mm Focal Length\u003c\/li\u003e\n\u003cli\u003eFast f\/3.8 Focal Ratio\u003c\/li\u003e\n\u003cli\u003eCarbon Fibre Sandwich Tube Construction\u003c\/li\u003e\n\u003cli\u003e\u0026gt;50mm Corrected Flat Field\u003c\/li\u003e\n\u003cli\u003e3\" Ceres Rack and Pinion 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 AG12 Optical Tube Assembly\u003c\/h2\u003e\n\u003cp\u003eThe Orion Optics UK AG12 Astrograph combines a 300mm primary mirror with a fast 1140mm focal length (f\/3.8) to capture faint deep-sky objects with significantly shorter exposures. Its integrated 4-lens ED corrector delivers a flat field greater than 50mm, producing pinpoint stars with spot sizes as small as 1.7µm on-axis and 4.6µm at the edge of the field. The entire optical tube weighs approximately 16kg and is housed in a rigid 980mm carbon fibre sandwich tube for thermal and mechanical stability.\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\u003eFast f\/3.8 Optics: A 300mm Aperture with a \u0026gt;50mm Flat Field\u003c\/h3\u003e\n\u003cp\u003eThe AG12 is engineered for wide-field deep-sky imaging, pairing a large 300mm aperture with an aggressive f\/3.8 focal ratio. This combination gathers immense amounts of light quickly, reducing the required sub-exposure time and allowing you to capture more data in a single night. The integrated 4-lens ED corrector flattens the field across an image circle greater than 50mm, fully illuminating large format CMOS and CCD sensors without vignetting or distorted stars at the edges.\u003c\/p\u003e\n\u003cp\u003eThe optical correction delivers incredibly tight star images, with a measured spot size of just 1.7µm on-axis and 4.6µm at the field edge. This ensures that whether you are imaging the vast star clouds of the Milky Way or the faint outer arms of a distant galaxy, the AG12 resolves fine details across the entire frame.\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 Construction: A 16kg Tube with 3-Fan Active Cooling\u003c\/h3\u003e\n\u003cp\u003eTo maintain precise focus through changing temperatures, the AG12 utilizes a carbon fibre sandwich tube. This material exhibits minimal thermal expansion, preventing the focal plane from shifting during long imaging sessions. The optical tube assembly weighs approximately 16kg and has a length of 980mm, requiring a robust equatorial mount for stable imaging.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e9-Point Mirror Cell:\u003c\/strong\u003e The primary mirror is supported by a CNC machined 9-point suspension cell, which prevents flexure and maintains collimation as the telescope moves across the sky.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eActive Cooling:\u003c\/strong\u003e Three controllable fans are integrated into the mirror cell to accelerate the cooling of the primary mirror, helping you reach thermal equilibrium faster for sharper images at the start of your session.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e110mm Secondary Mirror:\u003c\/strong\u003e The large secondary mirror is necessary to fully illuminate the wide, corrected field of the f\/3.8 system, ensuring bright, even fields for large-sensor cameras.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eImaging-Ready Focus System: 3\" Ceres Focuser and 79mm of Back Focus\u003c\/h3\u003e\n\u003cp\u003eThe AG12 comes standard with the robust 3\" Ceres rack and pinion focuser. This heavy-duty focuser is designed to carry complex imaging trains without slipping or flexing, ensuring your camera, filter wheel, and off-axis guider remain perfectly aligned. The 10:1 dual-speed reduction knob allows for incredibly fine adjustments, making it easy to achieve critical focus.\u003c\/p\u003e\n\u003cp\u003eA generous 79mm of back focus (focus distance to image plane) provides ample room to install a variety of accessories. This space is critical for accommodating filter wheels, off-axis guiders, and adaptive optics systems between the corrector and your camera sensor, giving you complete flexibility in configuring your imaging setup.\u003c\/p\u003e\n\u003cdiv class=\"DAV-bg-light\"\u003e\n\u003cdiv class=\"DAV-section\"\u003e\n\u003ch3\u003eComparing the Optical Grades\u003c\/h3\u003e\n\u003cp\u003eThe images below show the same view of Saturn captured through the included Professional grade and the optional Ultra (Lambda\/10 PV) upgrade, under identical conditions -- a visual illustration of the difference in contrast and fine detail the upgrade delivers.\u003c\/p\u003e\n\u003cdiv class=\"DAV-comparison-grid\"\u003e\n\u003cdiv class=\"DAV-comparison-item\"\u003e\n\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Orion-Optics-UK-Saturn-1_6-PV.jpg\" alt=\"Saturn viewed through 1\/6 PV Professional grade optics\"\u003e\n\u003cp\u003e1\/6 PV (Professional)\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-comparison-item\"\u003e\n\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Orion-Optics-UK-Saturn-1_10-PV.jpg\" alt=\"Saturn viewed through the Ultra (Lambda\/10 PV) grade optics upgrade\"\u003e\n\u003cp\u003eLambda\/10 PV (Ultra)\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e\n\u003c\/div\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 imaging sensor can the Orion Optics AG12 fully illuminate?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe AG12 is designed with a \u003cstrong\u003e4-lens ED corrector\u003c\/strong\u003e that produces a corrected, flat image circle \u003cstrong\u003egreater than 50mm\u003c\/strong\u003e in diameter. This is large enough to accommodate full-frame sensors (43mm diagonal) and even some medium-format sensors without significant vignetting or loss of star sharpness at the corners.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat kind of telescope mount is required for the AG12 OTA?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe AG12 optical tube weighs approximately \u003cstrong\u003e16kg\u003c\/strong\u003e and has a length of \u003cstrong\u003e980mm\u003c\/strong\u003e. When you add a large camera, guide scope, and other accessories, the total payload will be significantly higher. A robust equatorial mount with a payload capacity of at least 25-30kg (55-66 lbs) is recommended for stable, long-exposure astrophotography.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow does the f\/3.8 focal ratio of the AG12 benefit imaging the Andromeda Galaxy (M31)?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe fast \u003cstrong\u003ef\/3.8 focal ratio\u003c\/strong\u003e allows the AG12 to collect light very rapidly. For a large, relatively bright target like the Andromeda Galaxy (M31), this means you can capture its faint outer arms and dust lanes with much shorter sub-exposures compared to a slower f\/8 or f\/10 system. The \u003cstrong\u003e1140mm focal length\u003c\/strong\u003e provides an ideal image scale for framing the entire galaxy on a full-frame sensor.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the AG12 a good choice for high-magnification planetary imaging of Jupiter or Saturn?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eWhile the AG12's 300mm aperture provides high theoretical resolution, its primary design is for wide-field, deep-sky imaging. The large \u003cstrong\u003e110mm secondary mirror\u003c\/strong\u003e creates a significant central obstruction (approx. 37%), which reduces contrast on fine planetary details compared to a telescope with a smaller obstruction. For optimal planetary results, a Barlow lens would be required to increase the effective focal length.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eWhat is the purpose of the three cooling fans on the AG12's mirror cell?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe three controllable fans are part of the AG12's active cooling system. They draw ambient air across the back of the 300mm primary mirror, helping it reach the outside temperature more quickly. This process minimizes internal tube currents and ensures the sharpest possible images from the very start of an observing session.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eHow much space does the AG12 provide for an imaging train?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe AG12 provides \u003cstrong\u003e79mm\u003c\/strong\u003e of distance from the focuser's connection point to the corrected focal plane. This is known as back focus and is critical for astrophotography. This generous distance allows you to easily install accessories like an off-axis guider (OAG), a filter wheel, and any necessary adapters while still being able to bring your camera to a sharp focus.\u003c\/p\u003e\n\u003c\/div\u003e\n\n\u003cdiv class=\"DAV-accordion\"\u003e\n\u003ch3 class=\"DAV-accordion-Q\"\u003eIs the AG12 available in a higher optical grade?\u003c\/h3\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"DAV-accordion-A\"\u003e\n\u003cp\u003eThe AG12 ships with Orion Optics UK's Professional (1\/6 PV) hand-figured optics as standard, each supplied with its own Zygo interferometer test report. For imagers who want the tightest possible star images, an Ultra (Lambda\/10 PV) hand-figured optics upgrade is available, further reducing the spot sizes across the field.\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\u003eAperture\u003c\/td\u003e\n\u003ctd\u003e300mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocal Length\u003c\/td\u003e\n\u003ctd\u003e1140mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocal Ratio\u003c\/td\u003e\n\u003ctd\u003ef\/3.8\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCorrected Field Size\u003c\/td\u003e\n\u003ctd\u003e\u0026gt;50mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpot Size (On-Axis)\u003c\/td\u003e\n\u003ctd\u003e1.7µm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSpot Size (Field Edge)\u003c\/td\u003e\n\u003ctd\u003e4.6µm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBack Focus\u003c\/td\u003e\n\u003ctd\u003e79mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTube Weight\u003c\/td\u003e\n\u003ctd\u003eApprox. 16kg\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTube Length\u003c\/td\u003e\n\u003ctd\u003e980mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eTube Diameter\u003c\/td\u003e\n\u003ctd\u003e350mm\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\u003eSecondary Mirror Size\u003c\/td\u003e\n\u003ctd\u003e110mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePrimary Mirror Cell\u003c\/td\u003e\n\u003ctd\u003eCNC Machined Aluminium, 9-point suspension\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFocuser\u003c\/td\u003e\n\u003ctd\u003e3\" Ceres Rack and Pinion, 10:1 reduction\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCorrector Design\u003c\/td\u003e\n\u003ctd\u003e4-lens ED\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCooling System\u003c\/td\u003e\n\u003ctd\u003e3 controllable fans\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMounting Hardware\u003c\/td\u003e\n\u003ctd\u003eCNC machined aluminium cradles and dovetail\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\"\u003eAG12 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\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eCNC Machined Aluminium Cradles\u003c\/p\u003e\n\u003cp class=\"DAV-item-subtitle\"\u003e× 1 set\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/li\u003e\n\u003cli class=\"DAV-grid-item\"\u003e\n\u003cdiv\u003e\n\u003cp class=\"DAV-item-title\"\u003eDovetail Plate\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\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":"Professional (1\/6 PV)","offer_id":52942361067805,"sku":"OOUK-AG12-OPTICAL-TUBE-ASSEMBLY-ONLY","price":9466.15,"currency_code":"USD","in_stock":true},{"title":"Ultra (Lambda\/10 PV)","offer_id":52942361100573,"sku":"OOUK-AG12-OPTICAL-TUBE-ASSEMBLY-ONLY-2","price":9606.71,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0753\/5280\/1565\/files\/Orion-Optics-UK-Logo_5650e8c0-f065-4511-a557-7988771ce545.jpg?v=1789606706","url":"https:\/\/davidastro.com\/fr-us\/products\/orion-optics-uk-ag12-optical-tube-assembly-only","provider":"David Astro","version":"1.0","type":"link"}