- A Quantum Leap in Performance - The UP18's huge 18-inch diameter primary mirror gathers over 5 times more light than popular 8-inch reflectors or over twice the light grasp of a 12-inch telescope
- Outstanding Views - Premium quality, diffraction limited Newtonian optical systems are individually hand-figured to deliver stunning views of the heavens from dark sky sites
- Extreme Portability - Orion UP telescopes can be disassembled into ultra-compact packages so you can take them to your favorite dark-sky site without filling your car
- Light and Strong - The Orion UP Dobsonians feature precision machined all-metal construction. Fully assembled the UP18 weighs about 68 pounds, about half what traditional 18-inch scopes weigh!
- 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 10 times faster than regular solid mirrors.
- Fast Optics - The fast f/4.2 optical system delivers bright images and a short tube keeping the eyepiece less than 6 feet off 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.
- 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
If you are a serious deep sky observer pushing the limits of visual observing or if you wish you had the means to follow the extra-galactic wanderings of Sue French, Ken Hewitt-White or Steve Gottlieb in Sky and Telescope magazine or David Eicher, Richard Jakiel or Phil Harrington in Astronomy magazine, the Orion UP18 Premium Dobsonian is the tool for you. Eighteen-inch instruments have long been recognized by serious observers as a telescope big enough to give satisfying views, yet still easily transportable to dark sky locations by one person. The Orion UP18 not only delivers the premium optical experience you need to seriously explore our Universe, but tipping the scales at only 68lbs its half the weight of classical Dobsonian telescope and it disassembles into a compact package that will fit in nearly any car.
Every telescope design has a "sweet spot," a combination of design choices and parameters that make it excel at particular astronomical tasks. For example, long focal length refractors are great for double stars and planets, while short focal length refractors or reflectors can deliver exceptional views of large swaths of emission nebulas or dark lanes in the Milky Way. In the case of the Orion's UP Series of Premium UltraPortable Dobsonian telescopes, the sweet spot is a design optimized to offer serious observers' high-quality, large-aperture telescopes that are designed to break down into very compact packages that are about as large as one person can reasonably handle.
Features of the UP18:
Premium 18-inch Diameter Optics: With an Orion UP18 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 UP18 has a classical Newtonian configuration with a parabolic primary with a full 18-inch diameter of polished optical surface, not an 18-inch or 450mm blank with beveled edges. The Newtonian telescope is a favorite for serious deep sky observers and nearly ubiquitous for Dobsonian telescopes, with the UP18'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). This fast optical system also means the field-of-view is wide at low powers and the eyepiece is low to the ground, about 70" when the scope is pointed straight up, so most observers don't need a ladder to aim this telescope anywhere in the sky.
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. A Newtonian design of f/4.2 focal ratio does exhibit some amount of stellar enlargement at the extreme edge of a wide field eyepiece due to an optical characteristic called coma which is present is ALL Newtonian optical optics. The effect will vary with eyepiece and is so small that most observers won't even notice it unless they are specifically looking for it. Sharper star images at the edge of the field of view can be further enhanced by the addition of an accessory field corrector lens such as a Paracorr; although most observers feel they are getting totally satisfactory images without the need for such a corrector.
Enhanced Optical Coatings: The precision optical surface quality of the Orion UP18 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, 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 mirrors.
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 UP18 has a secondary mirror that is supported by a rigid three-arm secondary support structure that is attached to the back of the secondary mirror with three spring-loaded 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 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 UP18 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 the UP18, Orion has incorporated an advanced mirror technology - what we call "sandwich mirrors." The 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, Cal Poly San Luis Obispo and for the U.S. Army as well as in amateur telescopes around the world. 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 UP18 to reach thermal equilibrium up to 10 times faster than a traditional solid 18-inch mirror and means that the mirror can deliver great views even as the air around the telescope is changing. Even faster equilibrium can be reached if you add optional 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 views.
All Metal Construction: These telescopes aren't made in a garage or woodshop, 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 UP18 has been engineered to be light, but to possess superior rigidity. The Optical Tube Assembly (OTA) of the Orion UP18 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 are not 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 UP18 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 speed allows for critical focusing during high power visual observing or for 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 66 cm 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 OTA 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 views generated by the Orion UP18 are contrast-rich and allow chasing those "faint fuzzies" right up to the edge of bright stars.
Accessories: The UP18 comes with an Orion EZ Finder II Reflex sight, additional finder scope port, and primary mirror dust cover. Eyepieces are not included.
|Glass material||Soda-lime plate|
|Lowest useful magnification||65x|
|Highest useful magnification||300x|
|Limiting stellar magnitude||16.0|
|Optical quality||Diffraction limited|
|Finder scope||EZ Finder II|
|Focuser||2in. dual-speed linear bearing Crayford|
|Secondary mirror obstruction||79mm|
|Secondary mirror obstruction by diameter||17%|
|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||75.0 in.|
|Weight, optical tube||60.0 lbs.|
|Weight, mount/tripod||8.0 lbs.|
|Weight, fully assembled||68.0 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 - UP18 Premium UltraPortable Truss Dobsonian|