- A Quantum Leap over Traditional Reflectors - The UP20's huge 20-inch diameter primary mirror gathers over 6 times more light than popular 8-inch reflectors
- Outstanding Views - Premium quality, diffraction limited Newtonian optical systems are individually hand-figured to deliver stunning views of the heavens from dark sky sites
- Light and Strong - The Orion UP Dobsonians feature precision machined all-metal construction. Fully assembled the UP20 weighs about 96 pounds, about 60% what a traditional 20-inch scopes weighs!
- More Stable - Eight-pole, engineered double truss design ensures greater structural rigidity than competitive 6-pole telescopes.
- Patent-Pending Optical Technology - The Orion UP Dobsonians feature lightweight sandwich mirrors, optimized to cool down up to 20 times faster than regular mirrors
- Fast Optics - The fast f/4.2 optical systems deliver bright images and a short tube lengths, keeping the eyepiece less than 80-inches above the ground at all times
- Enhanced Reflectivity Mirrors - 96% reflectivity aluminum mirror coatings on the primary and the secondary mirrors grab as much light as possible for brighter images
- Smooth Operators - The UP20 telescopes have a gigantic azimuth ball bearing, over 25 inches in diameter, and use an exclusive laminate altitude bearing material
- Two Telescopes in One - Orion UP Truss Dobsonians are complete Dobsonian telescopes, but with the optional Dovetail Mounting Adapter, the OTA can be supported on sturdy equatorial mounts
At Orion, we really like telescopes. In fact, you might say we've never met a telescope we didn't like, since all of them have different strengths and can excel in different applications. Every telescope design has such a "sweet spot," a combination of design choices and parameters that make it excel at particular astronomical tasks. In the case of the Orion's UP20 Premium UltraPortable Dobsonian telescope, the sweet spot is a design optimized to offer serious observers a high-quality, large-aperture telescope experience for deep sky observing in a very portable package.
Why would you choose an Orion UP20? Simply put, "Aperture Rules."
Aperture is king when it comes to deep sky observing; the evidence is all around you. What type of scope allows you to tease out the most detail in a deep sky object? Usually the biggest Dobsonian available. Where are the biggest lines at star parties? The queue to look through those big Dobs. What kind of scope lets you most easily track down and confirm those faint Hickson Group and anonymous galaxies? A big Dobsonian, usually the bigger the better.
A 20-inch telescope is a serious telescope for serious observers. It takes commitment to haul around any kind of really big Dob telescope to dark sky locations. A traditional 20" Dobsonian, for example, usually weighs in at over 150 lbs. Of course, the fully assembled Orion UP20 is much lighter at approximately 96 lbs. The heaviest component is the mirror itself at 57 lbs. But more importantly than just being the lightest 20-inch telescope around, here is a truly large aperture telescope that breaks down into components that allow you to pack the scope and all your other observing gear in a compact car. If you want to grab a lot of light and still be able to pack your giant dob in your trunk and head off to dark skies, the Orion UP20 will provide a lifetime of satisfying observing.
Take it as a given that Orion's UP20 is easier to transport than many smaller traditional Dobsonians. However, only you can decide how much light collection power you need to cure your particular case of aperture fever!
Features of the UP20:
Premium 20-inch Diameter Optics: With an Orion UP20 you'll experience a premium optical system. Not only are the mirrors huge, but they are all individually hand figured to exacting standards to deliver diffraction limited performance of 1/8 wave or better. Orion's optical lab where these mirrors are polished and figured has even supplied optics to NASA - they're that good!
The UP20 has a classical Newtonian configuration with a parabolic primary mirror and flat secondary, a favorite for serious deep sky observers and nearly ubiquitous for Dobsonian telescopes, with the UP20's fast f/4.2 focal ratio, images are bright and contrast-rich (assured by Orion's effective baffling in the dual-speed focuser and the standard glare-blocking secondary cage light shield). These diffraction limited optics deliver sharp, contrast and detail-rich images at the center of the field of view that will only be limited by the atmospheric seeing and by the aperture of the optics. This fast optical system also means the field-of-view is wide at low powers and the eyepiece is low to the ground, about 79" when the scope is pointed straight up, so most observers only need a short stable step ladder to aim this telescope anywhere in the sky.
Enhanced Optical Coatings: The precision optical surface quality of the Orion UP20 Dobsonian is augmented by enhanced optical coatings to assure it collects as many photons possible to focus it into a bright and contrast-rich image. The primary mirror has an enhanced reflectivity, 96% aluminized coating with a protective over-coating of Silicon Dioxide (quartz) to protect the reflective aluminum coatings from oxidation from contaminants in the air and provide some level of surface protection from scratches. Likewise, the same high-efficiency coatings are on the precision, flat secondary mirror.
Fully Collimatable Optics: Premium optics won't perform well if you can't accurately collimate them (align them so the optical system delivers the converging light cone directly into the eyepiece with the eyepiece image plane being exactly perpendicular to the optical axis). The Orion UP20 has a secondary mirror that is supported by a rigid manganese steel, three-arm secondary support structure that is attached to the back of the secondary mirror with three adjustment screws that allow the tilt to be adjusted for collimation. The primary mirror can be centered within the telescope by eccentric cams and locked in position. The primary mirror also has a three point collimation system that adjusts the entire mirror, 9-point flotation system and steel mirror cell. The primary collimation system also features locking set screws to assure collimation is not lost once you align the mirrors.
Engineered Mirror Support: Premium optics are only as good as the support system they rest on. The UP20 has an extensively modeled 9-point suspension system. The frame of the mirror support is fabricated from steel and has lateral locking screws (for use on an equatorial mount) in addition to the locking screws on the collimation adjustments.
Patent-Pending Sandwich Mirror Technology: For its UltraPortable UP20, Orion has incorporated an advanced technological approach to mirror making - "sandwich mirrors." This sandwich mirror technology has been used to manufacture research-grade optical elements and proven by over a half dozen years of successful applications in amateur telescopes and at research facilities such as NASA, Cal Poly San Luis Obispo and for the U.S. Army. The Orion UP telescopes have lightweight sandwich mirrors that feature two solid glass plates separated by a thermally optimized "open core" - pillars of fused glass between the plates. The open core allows air to circulate freely in between the layers of the mirror. This design allows the mirror in a UP20 to reach thermal equilibrium 10 times faster than a traditional solid 20-inch mirror and means that the mirror can deliver great images even as the air around the telescope is changing. Even faster equilibrium can be reached if you add cooling fans to accelerate thermal acclimation.
Why 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 cooler than the mirror itself. Since a sandwich technology mirror cools far more rapidly than a solid mirror of the same thickness, this major source of distortion is eliminated quickly, giving you sharp images.
All Metal Construction: These telescopes aren't made in a garage or wood shop, they are fabricated from steel and aluminum. Orion chose an all metal design after extensive prototyping using wood and composite materials. These telescopes have been engineered to perform using 3D AutoCAD and FEA software. The mechanical structures have been extensively modeled to provide optimal thermal performance and stability. Machined with Numerical Control (NC) technology and hand fitted to assure proper fit and finish, these telescopes are a joy to look at as well as look through.
Two Trusses Are Better: The UP20 has been engineered to be light, but to possess superior rigidity. The Optical Tube Assembly (OTA) of the Orion UP20 is a double truss design, with a lower and upper set of truss tubes joined amidships by a welded aluminum frame. This design is not only extremely compact, strong and light, but also allows the use of an optional dovetail adapter bar to mount the OTA to a sturdy EQ mount (the dovetail adapter bar and equatorial mount aren't included).
Optimized Truss Poles: In addition to the dual-truss design, Orion has gone to the extra engineering effort and expense to optimize an 8-pole truss design for added stability. Having 8 thinner poles optimizes rigidity and minimizes weight.
Dual Speed 2" Linear Drive Crayford Style Focuser: The Orion UP20 Dobsonian 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 an rock-solid, super smooth focusing experience that can handle the weight of even the heaviest of modern eyepieces. Of course, its tension, the pressure on the drawtube, is adjustable to lock heavy equipment in place if desired. Being a Crayford-style design, named after Jack Wall of the Crayford Manor House Astronomical Society in England, there is no wobble in this focuser!
The two focus controls are knurled to allow ease of use, even when observing with gloves in cold conditions. The smaller of the two concentric focus controls adjusts the focus at a rate 10 times finer than the larger control wheel. This fine adjustment rate allows for critical focusing during high power visual observing or during imaging applications. The focuser has 2-inches of travel distance. If you've never used a dual-speed focuser before, one night's use with this focuser will make you a life-long convert.
Advanced Bearings: Dobsonian aficionados will tell you that the secret of "Dobsonian nirvana" is good bearings. The huge azimuth ball bearing is adjustable to suit the personal preference of each observer with a simple tension adjustment knob. The friction on the altitude bearings has been carefully optimized to allow easy altitude motion yet it is sufficiently stiff to allow the interchange of various visual accessories on the focuser and not (usually) require re-balancing of the Optical Tube Assembly with counterweights. Using sufficient resistance on the altitude bearing also assures that critical focus can be achieved at high power without the telescope moving off-target.
Optimized Light Baffles: With a carefully selected secondary mirror, baffled focuser and standard, removable secondary light shield, the images generated by the Orion UP20 are contrast-rich and allow chasing those "faint fuzzies" right up to the edge of bright stars. If you wish to observe in heavily light polluted areas, a full optional light shroud is available.
Accessories: The UP20 comes with an Orion EZ finder II reflex sight, primary mirror dust cover, and the upper truss-ring is drilled and tapped to accept an additional finder scope base. Eyepieces not included - we assume the serious observers who order this telescope already own an assortment of favorite oculars!
|Glass material||Soda-lime plate|
|Lowest useful magnification||65x|
|Highest useful magnification||300x|
|Limiting stellar magnitude||16.2|
|Optical quality||Diffraction limited|
|Finder scope||EZ Finder II|
|Focuser||2in. dual-speed linear bearing Crayford|
|Secondary mirror obstruction||89mm|
|Secondary mirror obstruction by diameter||18%|
|Secondary mirror obstruction by area||3%|
|Mirror coatings/over-coatings||Enhanced Aluminum and Silicon Dioxide|
|Astro-imaging capability||Simple moon shots|
|Bearing material||AZ: Ball Bearing, ALT: Teflon|
|Tripod material||Aluminum and Steel|
|Length of optical tube||84.0 in.|
|Weight, optical tube||86.0 lbs.|
|Weight, mount/tripod||10.0 lbs.|
|Weight, fully assembled||96.0 lbs.|
|Additional included accessories||EZ Finder II, 8-strut, double-truss optical tube Assembly, Pre-drilled cooling fan locations|
|Other features||Enhanced mirror coatings; 94% reflectivity, Aluminum tube truss struts|
|Name||Orion - UP20 Premium UltraPortable Truss Dobsonian|
|Manufacturer Part No||ORI-08937|
|Telescope Aperture||16.1" and Up|