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Orion SkyQuest™ XT8 8 Orion logo small (blue) 6,004 bytes

SkyQuest™ XT8 8"(20cm) Dobsonian

This model was discontinued in August 2003 when it was replaced by the new SkyQuestª XT8 Intelliscope™. But then due to popular demand for a more fundamental option, it was reintroduced as the Classic XT series in January 2004.

The first Orion product Company Seven chose to place on line!

The Orion SkyQuest™ Dobsonian telescopes are designed for beginners who seek the best possible view of the faint Deep Sky objects while on a constrained budget. These telescope benefit from years of study and refinement of those Dobsonian style telescopes already on the market; they include advanced design and materials to keep them lightweight and simple to use. Furthermore, the accessories included are common sense items to insure a good first night out; these are items that would normally be optional for competing telescopes.

While the original Orion SkyQuest™ XT8 telescope became the most highly recommended production 8" Dobsonian style telescope, and was the reference standard for its type at Company Seven, Orion simply couldn’t leave well-enough alone. Orion took the Dob that earned “best of the batch” honors from Sky & Telescope magazine (1/00) and enhanced it with even better engineered features, and accessories! And then Orion dropped the price, to boot.

Our popular Orion SkyQuest XT8 telescope now provides you even more bang for the buck. Great light-gathering power, point-and-view simplicity, great optics, a rock-stable mount, and a host of features not found on competing Dobs. For any astronomer seeking serious adventure, the XT8 has it all!

Above Right: The Orion XT8 8"f6 Dobsonian telescope, current October 2001 model shown (17,527 bytes).

This telescope provides 48 inch focal length (f6 focal ratio), a versatile choice for amateur astronomy. This is part of the equation that provides good portability while retaining a good range if useful magnifications. The 8" aperture model is our most popular "first telescope" Dobsonian reflector, particularly attractive among those who desire an easily manageable telescope with the light gathering and fields of view potential to recognize many of the most popular deep sky objects (Galaxies, Star Clusters, Nebulae, Planetary Nebulae, etc.).

And yet this telescope affords the good contrast and clarity qualities required for lunar and planetary observing which actually may show changes through out an observing season. With a comparatively small central obstruction, and fewer optical surfaces, the contrast and brightness can actually surpass more expensive and complicated designs such as the 8" Schmidt-Cassegrain telescope.

What characterizes a reflecting telescope?: The Optical Tube Assembly (OTA) is an arrangement of the classic Newtonian reflecting telescope. An English mathematician originated this optical design although Sir Isaac Newton first made it. This system employs two mirrors. The Parabolic "Primary" mirror (illustrated below, and as seen from behind the telescope optical tube at left) is the factor by which most telescopes are described; hence an 8" telescope has a primary mirror of 8 inch (203mm) in diameter with a versatile 1200mm mm focal length (f5.9). The Primary mirror of the telescope is precisely mounted in a Cell at the rear of the telescope.

The light entering the telescope is gathered and then reflects forward in a converging beam, to the elliptical Secondary Mirror that is positioned near the front of the telescope. This Secondary Mirror is supported in a tilted position so that to the light path the obstruction appears circular. The Secondary Mirror diverts the light from the Primary Mirror to the side and beyond the Focuser. The Secondary Mirror is attached to an adjustable Mirror Cell, and this assembly is held in place by a new (improved Oct. 2001) four vane Spider; this assembly is shown above and to the left as seen from the front of the telescope. The light from the Primary mirror is then reflected out to the side of the telescope achieving focus at a point beyond the focuser. An eyepiece for viewing, or camera for photography is placed at the focuser.

Parabolic Primary Mirror of an Orion Dobson telescope Left: Parabolic Primary Mirror of an Orion Dobson telescope in it's Cell (12,056 bytes).

Among the considerations of a reflecting telescope is that the mirrors be precisely positioned within the OTA in terms of centering, tilt, and spacing. The overall alignment ("collimation") of the one optical element to the other, and their placing the focal plane (the point where the image comes to focus) at the correct position beyond the focuser are critical. The optical axis of the telescope should be closely parallel to the mechanical axis of the tube assembly too.

Company Seven chose Orion's SkyQuest™ telescopes in part because of their consistently well engineered, good quality mechanical components, and partial assembly at the factory that facilitate collimating these telescopes precisely upon delivery, if needed.

Primary Mirror, Secondary Mirror holder, Focuser and Eyepiece of an Orion 8

Right: View of Primary Mirror, Secondary Mirror holder, Focuser with Eyepiece of an Orion 8"f4 reflecting telescope. (13,017 bytes).

A well made reflecting telescope can offer the best view per the dollar of the faint, deep sky objects where light gathering power is essential. Light gathering power increases are more important and come quicker than one may think; consider that a 6"f8 reflecting telescope may show objects about 335X fainter than the unaided eye, while an 8"f6 may offer 600 to 650X the light gathering power over the unaided human eye - in astronomy size can matter!

The Dobsonian telescope: The characteristic simple to use Alt-Azimuth mounting, use of a lightweight primary mirror and modestly priced components evolved in the 1970's with San Francisco sidewalk astronomer John Dobson. His goal was to get the most telescope possible into the hands of the amateur observer for the lowest relative cost. This arrangement has become known as the "Dobsonian" or "Dob".

The Dobsonian telescope consists of an optical tube assembly riding on a wooden alt-azimuth platform. The optical tube may be made of tube up to 18 or 20" in diameter. These tubes are typically made of Sonotube/cardboard, or plastic, or rolled metal. The Orion XT telescopes employ a rolled metal enameled tube finished internally in an anti reflection paint. This tube holds optical collimation well even with temperature or humidity changes. This thin wall tube permits the designer to select a smaller secondary mirror/obstruction. And this keeps the tube lighter weight and more compact than heavier Sonotube tubes. In the case of the better made larger Dobson telescopes (12-1/2 inch and larger), a Truss arrangement is employed in order to facilitate disassembly into a more manageable and compact package. Our best-made Dobson telescopes up to 10 inch aperture are those offered by Orion. While our larger Dobson telescopes include the Truss tube telescopes made by Astro-Systems.

Working with Gravity: The center of gravity lies directly over the center of rotation in both directions, so no matter to where the telescope is pointed, the weight is evenly distributed through the mount to the ground. This characteristic, and sound design results in almost complete elimination of unwanted vibration and oscillation; the inevitable downfall of many poor telescope mounts. Whereas in many economical telescopes the image seems to bounce around forever after the scope has been touched, this is not the case with well made Dobsonians. A Hands-On Telescope: The Dobsonian is a telescope you can push around - literally. You point it by simply nudging the tube on its Base up or down, and left or right by hand. Trunnions on the tube rotate on low-friction plastic bearings, allowing the telescope optical tube assembly to move up and down (altitude). The Base rotates horizontally (azimuth) around a center pivot permitting the observer to move the telescope smoothly up and down, left and right on Teflon/Nylon altitude and azimuth bearings. A gentle nudge is all it takes to point the scope right where you want it. The motion on both axes is "buttery smooth," letting you guide the scope with just the lightest touch from one part of the sky to another. Exploring the heavens is relaxing and fun for everyone, the way itÕs meant to be.

The XT8, like all SkyQuest Dobs, features the innovative Correct-Tension Friction Optimization system. It provides just the right amount of friction on the altitude bearings to ensure smooth motion and perfect tube balance. You donÕt have to rebalance the scope every time you change eyepieces or add a barlow lens or other accessories. No need for fishing sinkers, stacks of washers, or other clumsy counterweights as required with other Dobs! The CorrecTension springs also hold the optical tube captive on the base.

Trunnion arrangement of Orion Dobson telescope Left: The Trunnion arrangement of an Orion Dobsonian telescope. Note convenient lever with handle to move telescope up and down (11,022 bytes).

You do not need to loosen and tighten clamps when targeting objects, as you must with other mounts. Dobsonians are not equatorially mounted and so they are generally moved only by hand. While it is possible to add motors and computer control (to automatically find and track stars) it is generally not necessary or cost effective on smaller Dobsonians. Some companies do sell Dobs complete with tracking systems however, even these factory made tracking Dobsonians are not completely satisfactory for deep-sky astrophotography.

Nor do Dobsonian telescopes have setting circles for locating objects by their cataloged coordinates. Company Seven does offer optional electronic Encoder and digital display devices as aids to celestial navigation. Many people find the beauty of a Dob is in their no-frills simplicity - they just work. The Dobson design remains the first choice among serious deep sky observers, and it is not uncommon to find custom or home made 8" to 36" aperture "Dobs" in use at dark sky observing sites around the world.

The Orion SkyQuest™ Dobsonian telescopes sold by Company Seven in the 6" to 10" apertures provide excellent affordability and simplicity of operation, this makes these Dobsonians a great first telescope for entry into the hobby of amateur astronomy. Larger Dobs, though bulkier to transport and often requiring a step stool or ladder to reach the eyepiece, remain highly popular among experienced observers. Compared to similar-aperture Newtonians on their heavy equatorial mounts (and at times awkward eyepiece position), Dobsonians are delightfully economical. Experienced amateurs often claim that the best combination of portable telescopes for most persons pursuing astronomy would be an 18" to 20" Dobson, with a 6" Apochromatic Refractor!

Noteworthy features of the SkyQuest™ XT8 include: Accessories included with Orion SkyQuest™ XT8 Dobsonian Reflector (15,192 Bytes)

  • A set of accessories of good quality are provided to get you up and running the first night out!

    • Orion 25mm Plossl Eyepiece (49X providing 0.92 Degree Field of View)
    • Orion 9mm Plossl Eyepiece (136X providing 0.36 Degree Field of View)
    • Orion 6x30mm Finderscope with Quick Release Mounting Bracket
    • Collimation cap to aid collimation of the telescope mirrors
    • Eyepiece Holder
    • Plastic snap-on OTA Cover

  • Adjustable Friction, Altitude Bearings
  • Low-mass molded molded expertly finished Primary Mirror made of "Ultraplex", a type of plate glass marketed for optical use
  • Primary and secondary mirrors are aluminized and over coated with a transparent Silicon Monoxide protective coating assuring good longevity
  • Unique adjustable Mirror Cell to support the Primary Mirror
  • Durable aluminized mirror coatings
  • Optics hand finished and tested on a 125 line Ronchi
  • Silky smooth cast and machined aluminum 2" diameter Rack & Pinion Focuser
  • 2" to 1.25" accessory adapter
  • Focuser Lock
  • Convenient "Navigation Knob/Grip" on the optical tube.
  • Convenient grip/carrying handle on the Base.
  • Aluminum bracket to conveniently store one 2" (or 1.25") and three 1.25" eyepieces.

Receive a FREE Starry Night Special Edition software suite. Both the highly acclaimed planetarium software by Imaginova "Starry Night Special Edition" with a bonus "SkyTheatre" DVD are included FREE with purchase of any Orion-brand astronomical telescope from Company Seven.

"Starry Night Special Edition" is a basic version of the more capable "Starry Night" version 5.0 astronomy software series; this software will help you learn the night sky, see what is up day or night, now or in past millennia, plan your observing sessions, and print out charts and information about the celestial wonders. The set also includes "SkyTheatre", a DVD by Imaginova so your television or PC becomes a spaceship on a voyage through our Solar System. The set is compatible with both Macintosh computers running OSX version 10.3 or later, and with Windows XP for PC. Your personal planetarium and guide to the night sky!

Left: CD-ROM "Starry Night Special Edition" with bonus "SkyTheatre" DVD suite (43,322 bytes).
Click on image to view enlargement (85,180 bytes).

  XT8 8"f6 Telescope Specifications:

    Maximum Height Overall:
    Maximum Height to The Eyepiece:
    Length of Optical Tube Assembly:
    O.A. Diameter of Optical Tube Front Cell:

    Weight of Optical Tube Assembly:
    Weight of Carriage:

    Effective Light Gathering Power:
    Magnitude Limit Visual:

    50 inches (with lens cover)
    45 inches
    46 inches (with lens cover)
    9.22 inches (234mm)

    20.5 lbs.
    21.5 lbs.

    About 590X that of Human Eye
    About 13.8

    * Specifications are subject to change without notice.

To read additional information about the Orion SkyQuest™ XT8 telescopes
sold by Company Seven feel free to download the Orion illustrated
instruction manual from Company Seven's Library.

Note: this download size is 426,043 bytes (in Acrobat Reader ".pdf" format).


All of the information we provide on line and by phone or E-Mail to the customer, our expertise, our unrivaled showroom and museum (an increasing rare sight), and the fact that one may buy the basic instrument from us or elsewhere at about the same cost should be enough to persuade one to choose Company Seven. However, we do even better, we make it in your interest to buy from us.

Orion has been quite good at making the factories overseas produce a great value. But once in a while something less than perfect slips by; a part is not glued just right, something is installed a bit off, or a component is damaged in transit. If you receive one of these telescopes and if you know enough to recognize an anomaly then it is a simple matter to call Orion or Company Seven for a prompt exchange or replacement parts. We both have very good reputations for after sale support and a money back guarantee.

    "a series of subtle improvements that can transform an instrument into something wonderful"
But for those who can make the pligrimage to our showroom and pickup an assembled instrument, they do so with the assurance that their telescope will be "ready to rock" that critical first night out! For a relatively modest fee of $95 Company Seven will assemble our XT telescope Optical Tube Assembly and Base for you. This is similar to the standard service we have offered for more than twenty years on our more costly telescopes, and it is at times misunderstood and unappreciated by those who are ignorant of what we do. Let us try to demystify this a bit - now keep in mind that this all starts and ends with our technicians who have many years of experience building amateur and industrial telescopes. Our services provide a telescope that realized its highest potential. Think of this as a service provided by a most expert piano tuner - someone with a great ear for the instrument who could make a series of subtle adjustments or improvements that can transform an instrument from something merely adequate into something wonderful.

When we assemble the XT we evaluate cosmetics, often cleaning off surplus glue or dirt. We install the Primary Mirror making those first and most time consuming adjustments to assure each optical and mechanical component is nominally installed. We are happy to provide you with the optional tools to collimate a telescope when it becomes necessary (after all some years from now you will probably want to pull the mirror for cleaning) and more importantly we will teach you how best to proceed. As we have worked on so many of these instruments we have developed a good sense of how a properly made and adjusted Focuser should feel. We know the tricks to make the telescope move smoother up and down, left and right. We know how to make it last longer - in fact we change out some components with superior alternatives. We find the quality control problems however, while we do not expect a "Rolls Royce" fit and finish on the XT telescopes, we work so that the telescope will perform as well as experience shows it can. And as we process the telescope we perform some tests that will reveal to our experienced eye whether or not the optics were made and collimated as they could be. And finally, we generate additional information that is provided to the owner; this will characterize the potential of the telescope for visual applications, and with an optional Equatorial Mount what the XT may accomplish photographically.

One will never read a sad tale from someone who actually bought their XT at Company Seven. We invite you to attend a Star Watch activity of any regional astronomy club and compare a telescope that bears the Company Seven acceptance label with those from elsewhere. In fact more and more we hear accounts of people at such events who bought their "Orion XT clone" elsewhere being convinced it was a great value until they felt the motion of our telescopes and gazed through the eyepieces we recommended.

Company Seven's customers tend to progress further in the hobby than others. This is in part because we are helping them as we wish someone else would have helped us. We are not archetypical salesmen, instead we are experts who can teach you about the instruments and provide the sincere good counsel.

    "expert counsel brings value to a transaction, and profit should be the reward for a job well done"


These are optional accessories that are not included with the telescopes that we highly recommend for your viewing pleasure and long term success:

  1. Guide book: "Backyard Astronomers Guide" or "Nightwatch" by Terrence Dickinson, or "Starware" by Phil Harrington. For the novice from age 8 to 15 or so up to adult. Good introductions to astronomy, the use of telescopes, and their accessories. Easy introductions to finding ones way around the night sky.

  2. Telrad illuminated sight: to aid one in finding and centering objects in the main telescope, and learn the sky by "star hopping" from one object to another

  3. David H. Levy Guide to the Stars Planisphere (32,473 bytes) David H. Levy Guide to the Stars Planisphere If you are not familiar with the night sky then Company Seven recommends you buy a good simple Planisphere which makes it very easy for one to find out what constellations and major deep sky objects are overhead at any given time of the day or night.

    The night sky is mapped with the Constellations being those patterns recognizable to man since time immemorial. Constellations can be thought of as countries or states on a world map, where if you seek the Grand Canyon then you know to find Arizona. While in the night sky when one seeks the Great Nebula then one looks toward the Constellation Orion. The Planisphere is a two piece assembly consisting of one disc with a chart of the entire night sky, and an attached overlay disc with a transparent window and surrounding mask to simulate the horizons. The overlay is dialed to line up its local time indicator marks with the Month and Day printed around the edge of the chart disc, and so when properly set this will reveal what parts of the sky may be seen at any time of the year. The print is easy to read under day or red light.

  4. Once you begin to understand the way the night sky works with your Planisphere, the next step we suggest is to buy the Orion DeepMap 600 folding laminated Star Chart, edited by Steve Peters. Originally printed in 1997, the revised "Orion DeepMap 600" is among those indispensable publications that Company Seven recommends to anyone interested in learning their way around the night sky. The editor Steve Peters conceived of this as a very helpful device for anyone interested in astronomy and who may little or no observational experience. This has become the most popular chart of the night sky among our customers who are new to the hobby and who buy a telescope or binocular and now seek out what to see and when. This is often bought as a economical but valued and durable gift.

    Fully color illustrated, it is the first-ever star chart that folds up like a road map! DeepMap 600 shows the positions of more than six hundred of the finest celestial objects visible from the Northern Hemisphere. Each of these objects are plotted on a giant 33 x 21 inch full-color star chart by world-renowned celestial cartographer Wil Tirion. But what really makes this star chart invaluable is its convenience; it folds "accordion style" into a thin, pocket-size 4-¾ x 10-½ inches format - just like a road map!

    The chart is easy to read, and you will see more of the night sky when reading this with an optional red flashlight

  5. Red LED Flashlight such as the Rigel Skylite to help one set up and use a telescope, and to read charts or a planishpere without adversely impacting the observers night vision.

  6. AstroSystems Collimating tool set, thease are provided with good with instructions. Or for those who want a very accurate, and easy to use collimator then we recommend you consider our holographic Glatter Laser Collimator devices; even though documentation is included these require some training to obtain best results, and our staff is more than capable to help you learn how to use these.

  7. Neutral Density and Color Filters to reduce the brightness of the Moon and Planets, and highlight subtle features.

  8. Sky Light Pollution Rejection Filter to reduce the greenish or golden background glow from city lights and darken the sky background - aid seeing faint Nebulae.

  9. Improved 2" to 1.25" accessory adapter with non-marring clamp to securely hold eyepiece, threaded to accept 48mm filters so that you will only need to buy one standard size filter for use with either 1.25" or 2" eyepieces.

    Orion SkyQuest™ Dobsonian OTA in Padded Bag (23,768 Bytes)

  10. Orion fitted Carrying Bag for safer, and more convenient transport the telescope optical tube assembly. Keep in mind that these are very convenient and lightweight bags, but are not suitable for shipping a telescope.

  11. Eyepieces: Orion includes two eyepiece with this telescope, 9mm and 25mm Plossls. Typically astronomers will wish to initially set up the telescope with at least two or three eyepieces to address:

    • Low magnification: for views of the faint deep sky objects a 32mm to 35mm focal length eyepiece (ideally a well designed 2" wide angle ocular).

    • Middle Magnification eyepiece - usually between 80 to 120X, for views of the full Moon, Star Clusters, etc.

    • High magnification: 200X or more for views of the planets

    Eyepiece designs such as the Plossl, Orthoscopic are acceptable. If you object to less than perfect images particularly at the edge of the field, and if you require long eye relief (distance from lens to the eye) to accommodate spectacles, then Company Seven recommends eyepieces of advanced designs such as those pioneered by Al Nagler, founder of the TeleVue company. TeleVue's advanced designs include the "Nagler", "Radian", or "Panoptic" series eyepieces. These oculars will provide the widest clear, and flat field images bringing out the most in your telescope (and many other) telescopes. Wider field of views are also desirable since as the Earth rotates and objects drift across the field of view, a wide angler ocular shows an object for some time longer before having to adjust the telescope.

    Please refer to the brochure and the test report/data from Company Seven enclosed with our telescopes for detailed characterizations of suggested eyepieces:

      Eyepiece Magnification Actual field of view Exit pupil
      40mm Plossl 31x 1.27 degrees 6.66mm
      35mm Panoptic (2") 38x 1.82 degrees 5.83mm
      32mm Plossl 38x 1.26 degrees 5.33mm
      25 Plossl (included) 49x 0.92 degrees 4.16mm
      22mm Panoptic 55x 1.17 degrees 3.66mm
      19mm Panoptic 64x 1.00 degrees 3.16mm
      15mm Plossl 81x 0.59 degrees 2.50mm
      12mm Radian 102x 0.58 degrees 1.50mm
      9mm Nagler Type 6 136x 0.58 degrees 1.50mm
      9mm Plossl (included) 136X 0.36 degrees 1.50 mm
      6mm Radian 203x 0.30 degrees 1.00mm
      5mm Nagler Type 6 244x 0.33 degrees 0.83mm

  12. Equalizer: A slip fit machined bronze, heavy 2 to 1.25 inch diameter reducer adapter. Helps to keep telescope balance when switching to and from light and heavy accessories and eyepieces. Particularly helpful when using telescope with Alt-Azimuth mounts.
  13. Barlow or TeleVue "Powermate" Lens: Company Seven suggests you consider any of a number of 1.25 inch diameter Barlow lenses that we offer to double your magnification. You may find it helpful to contact Company Seven for suggestions on how to to best meet your goals.

  14. These XT telescopes put the eyepiece at position that is only about 4 feet (1.2 meters) from the ground. Since most of our customers are taller than that, they will find it uncomfortable to stand bent over to observe for extended periods. For a much more enjoyable and comfortable observing experience, Company Seven recommends the Observing Chair; this is our most comfortable, flat folding, adjustable height seat. It is not inexpensive, but is so practical and can be used for camping or other times when a comfortable portable seat is desired.

  15. Equatorial Mount: being constructed of an aluminum tube, some time in the future you could buy a good quality used equatorial mount and improve the usability of this telescope to better attain its high magnification potential. A telescope of this length and torque requires a good quality, rigid platform to support it. We recommend you consider:

    • Losmandy Hollywood General Machining Model GM-8 mount.
    • Losmandy Hollywood General Machining Model G-11 mount.
The telescope is available assembled and precisely collimated by Company Seven's experienced staff. While delivery is available, we suggest pickup in our showroom followed by attendance at our complimentary course of instruction. And of course the Orion One Year Limited Warranty is complimented by Company Seven's own guarantees and service facilities. With proper use and maintenance, there is very little that can go wrong with a telescope such as this - if there is a problem then it is likely we will have found it for you and so with the exception of mirror coatings, Company Seven backs our telescopes for life.

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