{"product_id":"hubble-optics-20-premium-ultra-lightweight-dobsonian","title":"Hubble Optics 20\" Premium Ultra Lightweight Dobsonian","description":"\u003cdiv\u003e\n\u003ch4 class=\"core-feature-title\"\u003e\u003cspan style=\"color: rgb(227, 13, 13);\"\u003ePRICES INCLUDE SHIPPING TO CANADA - ITEMS ARE SHIPPED DIRECT FROM MANUFACTURER\u003c\/span\u003e\u003c\/h4\u003e\n\u003cul class=\"overview-text\"\u003e\n\u003cli\u003eA quantum leap in optical performance - the UL 20 Truss Dobsonian telescope's huge 20\" diameter primary mirror gathers more than 6 times more light than popular 8\" reflectors or almost three times of the light grasp of a 12\" telescope\u003c\/li\u003e\n\u003cli\u003eA Premium, Light, Compact and Portable Design - About half the weight of traditional Dobsonian telescopes\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3 class=\"header\"\u003eUL20 Specs\u003c\/h3\u003e\n\u003cul class=\"ul-with-padding\"\u003e\n\u003cli\u003eOptical diameter:508mm\u003c\/li\u003e\n\u003cli\u003eFocal length : ~1676mm (f\/3.3), ~1880mm (f\/3.7), ~2134mm (f\/4.2)\u003c\/li\u003e\n\u003cli\u003eEyepiece height at zenith: ~1490mm(~59 in, f\/3.3), 1745mm (~69 in, f\/3.7), 2000mm (~79 in, f\/4.2)\u003c\/li\u003e\n\u003cli\u003eOptics type: Parabolic\u003c\/li\u003e\n\u003cli\u003eEyepieces: Not included\u003c\/li\u003e\n\u003cli\u003eOptical quality: Diffraction limited++ (Strehl 0.95+ for the primary mirror, 1\/10 lambda or better in PV for the secondary mirror)\u003c\/li\u003e\n\u003cli\u003eFinder scope: Not included\u003c\/li\u003e\n\u003cli\u003eFocuser: 2\" dual-speed linear bearing Crayford\u003c\/li\u003e\n\u003cli\u003eSecondary mirror obstruction: 100 mm (f\/3.3, f\/3.7), 90mm (f\/4.2)\u003c\/li\u003e\n\u003cli\u003eSecondary mirror obstruction by diameter: 19.7% (f\/3.3, f\/3.7), 17.7 (f\/4.2)\u003c\/li\u003e\n\u003cli\u003eSecondary mirror obstruction by area: 3.9% (f\/3.3, f\/3.7), 3.1% (f\/4.2)\u003c\/li\u003e\n\u003cli\u003eMirror coatings\/over-coatings: 96% Enhanced coating on both of the primary and secondary mirrors\u003c\/li\u003e\n\u003cli\u003eTube material: 6063-T6 Aluminum Alloy tubes with black zinc plated steel knob screws; Aluminum Alloy main structure (OTA and mount) and structure steel mirror cell.\u003c\/li\u003e\n\u003cli\u003eLength of optical tube : 73 in (f\/3.3, f\/3.7), 83 in (f\/4.2)\u003c\/li\u003e\n\u003cli\u003eWeight, optical tube : 76 lbs (f\/3.3,f\/3.7), 77 lbs (f\/4.2)\u003c\/li\u003e\n\u003cli\u003eWeight, fully assembled : ~88 lbs. (f\/3.3, f\/3.7), ~89 lbs (f\/4.2)\u003c\/li\u003e\n\u003cli\u003eAdditional, optional accessories: 8x50 Finder, Shroud, Wheelbarrow, Vinyl foam Cushioned Grips\u003c\/li\u003e\n\u003cli\u003eOther features: Sling lateral support and deluxe push-pull brass knob collimation screws\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e\n\u003cdiv class=\"text-block-container-grey\"\u003e\n\u003chr\u003e\n\u003ch3 class=\"header\"\u003eFeatures of the UL20:\u003c\/h3\u003e\n\u003cp class=\"feature-title\"\u003eExclusive Sandwich Mirror Technology:\u003c\/p\u003e\n\u003cp\u003eOur sandwich mirror technology has been used to manufacture research-grade optical elements and proven by over a half dozen years of successful applications at research facilities such as NASA, California State Polytechnic University San Luis Obispo, for the US Army, and in amateur telescopes around the world. Hubble sandwich mirror’s open core and close back design not only allows air to circulate through the mirror, but also provide the maximum structure strength to allow a simpler mirror cell design. Our sandwich mirror will reach thermal equilibrium up to 10 times faster than a traditional solid mirror and means the mirror can deliver great views even as the air around the telescope is changing temperature.\u003c\/p\u003e\n\u003cp\u003eWhy is thermal equilibrium so critical? The main issue is \"mirror seeing,\" the turbulence seen through the eyepiece of the telescope when the air above the mirror is different from the mirror itself. Since a sandwich mirror cools far more rapidly than a solid mirror of the same thickness, this major source of distortion is eliminated quickly, giving you sharp and stable views. With ever- changing temperatures during observing or imaging, your thick and solid mirror may never reach equilibrium, and never reach its full optical potential. This is one of the major reasons why our lightweight-sandwich mirror has superior optical performance in real world situations, even without an active cooling system. (Active cooling systems, such as fans, introduce their own problems, such as micro vibration, which may seriously degrade the image quality.) Our sandwich mirrors reach equilibrium extremely fast, and without any external disturbing aid.\u003c\/p\u003e\n\u003cp class=\"feature-title\"\u003eEnhanced Optical Coatings:\u003c\/p\u003e\n\u003cp\u003eThe Hubble UL20 primary mirror and the secondary mirror are coated with the state of the art 96% Enhanced optical coatings to assure it collects as many (while scattering as little) photons as possible to focus it into a bright and contrast-rich image. The optimal 96% Enhanced coating has multiple over-coating of precision controlled dielectric layers to maximize the reflectivity and provide excellent chemical and mechanical protection for the mirror coating.\u003c\/p\u003e\n\u003cp class=\"feature-title\"\u003eA Real Mirror Cell In A Real Mirror Box:\u003c\/p\u003e\n\u003cp\u003eThe UL20 has an extensively modeled and optimized 18-point flotation system that provides more than adequate support for the sandwich mirror. The three-point Push-Pull collimation system is completely independent from the sling lateral support. It will totally eliminate the often-found potato chip astigmatism introduced by sling belt when using the simple 3 pivoted bolts collimation system. In a simple pivoted bolts collimation system, the collimation of the primary mirror may cause the sling belt to pull the mirror axially on the mirror edge, bending the mirror to a potato-chip shape, causing annoying astigmatism. It also comes with a real mirror box for easy and safe mirror protection and transportation.\u003c\/p\u003e\n\u003cp class=\"feature-title\"\u003eAll Metal Construction:\u003c\/p\u003e\n\u003cp\u003eThe UL20 mechanical structures have been extensively modeled via 3D CAD and advanced FEA to provide the optimal structure strength and stability. Machined with Computer Numerical Control (CNC) technology and hand fitted to assure proper fit and finish. Super strong T6063-T3 aluminum alloy truss tubes, structure steel mirror cell and aluminum alloy OTA and mount structure. Completed with deluxe and environmentally friendly black powder coating, it is such a pleasure to look at, not to mention the enjoyment to look through.\u003c\/p\u003e\n\u003cp class=\"feature-title\"\u003eDual-Speed 2-inch Linear Drive Crayford Focuser:\u003c\/p\u003e\n\u003cp\u003eThe Hubble UL20 comes with a precision dual-speed, 2-inch diameter focuser. It's a beautiful piece of precision machining that enhances the viewing experience as well as the overall impression of a premium quality instrument you'll have with this telescope. This focuser is robust! It is a zero-backlash \"Crayford-style\" design further enhanced with modern \"linear bearings\" meaning you get a rock-solid, super smooth focusing experience that can handle the weight of even the heaviest of modern eyepieces. Its tension, the pressure on the drawtube, is preset to a very reasonable level, but adjustable to lock heavy equipment in place if desired. The smaller stainless steel focus control adjusts focus at a rate 8 times finer than the larger focus wheels. This fine adjustment allows for critical focusing during high power visual observing or for imaging applications. The focuser has 50mm of travel distance.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003chr\u003e\n\u003ch3 class=\"header\"\u003eShould I choose the f\/3.3, f\/3.7 or f\/4.2?\u003c\/h3\u003e\n\u003cp class=\"feature-title\"\u003eAdvantages of f\/4.2:\u003c\/p\u003e\n\u003cul class=\"ul-with-padding\"\u003e\n\u003cli\u003eSharper images. It has almost 50% less coma than UL20 f\/3.7; a coma corrector will still be helpful, but many people may live without it.\u003c\/li\u003e\n\u003cli\u003eWith the special introduction offer, you save $1,300 over UL f\/3.7!\u003c\/li\u003e\n\u003cli\u003eSmaller central obstruction, 3.5” (f\/4.2) v.s. 4.0” (f\/3.7) secondary mirror\u003c\/li\u003e\n\u003cli\u003eEasier to achieve perfect collimation\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp class=\"feature-title\"\u003eAdvantages of f\/3.3 and f\/3.7:\u003c\/p\u003e\n\u003cul class=\"ul-with-padding\"\u003e\n\u003cli\u003eNo ladder is needed for f\/3.3 at all; while you may need one-step ladder for an f\/4.2 when close to zenith direction.\u003c\/li\u003e\n\u003cli\u003eWider FOV for f\/4.2, and even wider with f\/3.3!\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eThe f\/3.3, f\/3.7 and f\/4.2 will all provide you with excellent views. A coma corrector is recommended for the UL20 f\/3.3.\u003c\/p\u003e\n\u003cp\u003eWith our unique two-section truss tubes for f\/4.2 (one section truss for f\/3.3 and f\/3.7), f\/4.2 is just as portable and strong as f\/3.3 and f\/3.7. At the end, it is really your personal preference. Please note that some counter weight (real and\/or a virtual spring counter weight) will be required for f\/4.2 at the bottom(and for f\/3.3 at the top), which is NOT provided\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003chr\u003e\n\u003ch3 class=\"header\"\u003eHappy Customers\u003c\/h3\u003e\n\u003ca href=\"https:\/\/hubble-optics.com\/UL20.html#happy_1\"\u003e\u003cimg class=\"img-responsive thumbnail image-50-percent\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0224\/6770\/6960\/files\/UL20-BRUCE1.jpg?v=1765050767\"\u003e\u003c\/a\u003e\n\u003cdiv class=\"caption\"\u003e\n\u003cp\u003eBruce's customized UL20. Charlie is holding the camera. Rich Mitchell is holding the secondary mirror\u003c\/p\u003e\n\u003c\/div\u003e\n\u003ca href=\"https:\/\/hubble-optics.com\/UL20.html#happy_2\"\u003e\u003cimg class=\"img-responsive thumbnail image-50-percent\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0224\/6770\/6960\/files\/UL20-Hiro.jpg?v=1765050772\"\u003e\u003c\/a\u003e\n\u003cdiv class=\"caption\"\u003e\n\u003cp\u003eHiroaki with his UL20.  \"UL20 is working excellent. The mirror quality is excellent...\"\u003c\/p\u003e\n\u003c\/div\u003e\n\u003ca href=\"https:\/\/hubble-optics.com\/UL20.html#happy_3\"\u003e\u003cimg class=\"img-responsive thumbnail image-50-percent\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0224\/6770\/6960\/files\/Tom.png?v=1765050775\"\u003e\u003c\/a\u003e\n\u003cdiv class=\"caption\"\u003e\n\u003cp\u003eWanted to take the time and say thank-you for the excellent 20\" f4.2. Wow is this mirror smooth and precise! Had one chance to see Saturn low in the sky, in September with stable seeing conditions. Uranus is finally getting higher, to chase good seeing. Where I am located south-west of Buffalo NY near lake Chautauqua, mostly have the jet stream overhead and never have stable seeing, except in the summer months. The site where the scope is, is dark and the deep sky views outstanding! I counted 26 galaxies in NGC 507 group at 200x in Pisces-Andromeda border. I'm using a Denkmeier 2 binoviewer and 3 power switch and A45mm OCS -1.2x 1.8x 2.25x with 24mm panoptics (107x 160x 200x ) and 35mm Baader eudiascopics I special ordered from Germany, just for this scope. Also color is brilliant as blue-greens are in planetary nebulae with this mirror ! Looking forward to seeing the pink rim in IC 418 this winter\u003c\/p\u003e\n\u003cp\u003e- Thanks! Tom Bakowski\u003c\/p\u003e\n\u003c\/div\u003e\n\u003ca href=\"https:\/\/hubble-optics.com\/UL20.html#happy_4\"\u003e\u003cimg class=\"img-responsive thumbnail image-50-percent\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0224\/6770\/6960\/files\/UL20-Ian.jpg?v=1765050778\"\u003e\u003c\/a\u003e\n\u003cdiv class=\"caption\"\u003e\n\u003cp\u003eJust dropping you a line to let you know how much I love my 20\" telescope. My wife feels like she dropped to my no. 2 slot ever since she got me the telescope. Thanks again for making the purchase an easy experience and standing behind your products.\u003c\/p\u003e\n\u003cp\u003e- Ian Glasgow\u003c\/p\u003e\n\u003c\/div\u003e\n\u003c\/div\u003e","brand":"Hubble Optics","offers":[{"title":"f\/3.3","offer_id":44336075571419,"sku":"UL20 f\/3.3","price":10913.0,"currency_code":"CAD","in_stock":true},{"title":"f\/3.3 with GoTo","offer_id":44336083861723,"sku":"UL20G f\/3.3","price":13713.0,"currency_code":"CAD","in_stock":true},{"title":"f\/3.7","offer_id":44336083894491,"sku":"UL20 f\/3.7","price":9653.0,"currency_code":"CAD","in_stock":true},{"title":"f\/3.7 with GoTo","offer_id":44336083927259,"sku":"UL20G f\/3.7","price":12453.0,"currency_code":"CAD","in_stock":true},{"title":"f\/4.2","offer_id":44336083960027,"sku":"UL20 f\/4.2","price":8533.0,"currency_code":"CAD","in_stock":true},{"title":"f\/4.2 with GoTo","offer_id":44336083992795,"sku":"UL20G f\/4.2","price":11333.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0224\/6770\/6960\/files\/hubble-optics-telescope-hubble-optics-20-premium-ultra-lightweight-dobsonian-40094952358107.jpg?v=1697556734","url":"https:\/\/telescopescanada.ca\/products\/hubble-optics-20-premium-ultra-lightweight-dobsonian","provider":"Telescopes Canada","version":"1.0","type":"link"}