| Many observers believe that an 8” aperture f/6 Dobsonian reflector provides the perfect balance of light gathering, resolution, and economy for the amateur astronomer. The Orion SkyQuest XT8 Classic is just such a scope, and an outstanding value, as well. It is big enough to keep you happily observing for the rest of your life, yet not so big that it becomes inconvenient to set up on the spur of the moment for a half hour or so of observing. Its performance and convenience makes it the perfect big scope for the newcomer to astronomy. In a review of six 8” Dobsonian telescopes a few years back, Sky & Telescope pronounced it the “best of the batch.” And Astronomy magazine said in a more recent review that it “brought easy enjoyment to deep-sky observing.” The Orion SkyQuest XT8’s great light-gathering capacity (over 800 times greater than the human eye) makes it ideal for capturing faint deep space wonders. Binary stars, open and globular star clusters, faint nebulas and galaxies – all are revealed in exceptional and subtle detail, even through mildly light-polluted suburban skies. At the same time, excellent planetary and lunar images are yours for the looking, although a neutral density filter is generally needed to cut down the brightness of these solar system objects. The scope is human powered. You move the scope manually – which is faster, quieter, and much less expensive than a motorized system. With only two major components to assemble (tube and base), and a heaviest single component weight of a little over 21 pounds, the scope takes only a few minutes to set up and is easily managed by any reasonably fit individual. It can be used in your back yard or at a distant dark sky site (the preferred observing location if you want to get the most out of its faint object observing capabilities). Its good optical quality and very reasonable price make it an excellent buy for the beginner or advanced astronomer alike. This Telescope’s Optical System . . . Newtonian reflector optical tube: 8” (203mm) aperture classical Newtonian optics, 1200mm focal length, f/5.9 focal ratio. The durable 44.5” long x 9.25” diameter rolled steel optical tube is finished in gleaming black enamel. It weighs only 20.3 lbs, making it easy to transport and assemble in the field. Fully coated optics: The 8” soda-lime plate glass parabolic primary mirror is coated with highly reflective aluminum and then overcoated with a protective layer of silicon dioxide (quartz) for long life. Primary mirror cell: Die cast aluminum cell with an open back design for faster cool down times. A battery-operated cooling accelerator fan that mounts on the rear cell is also available as an option. Push-pull locking collimation screw pairs help hold the correct collimation longer. Diagonal mirror: The 1.85” m.a. soda-lime plate glass diagonal is also coated with aluminum and then overcoated with a protective layer of silicon dioxide for long life. It is mounted in a fully-collimatable mirror holder on a thin four-vane spider for minimum diffraction. Finderscope: The EZ Finder II non-magnifying illuminated red dot finder projects a small dot of red light on a clear viewing window. The dot is focused at infinity to show you precisely where your scope is pointed. Simply move the scope until the red dot on the 10° wide viewing window lines up with an object you want to see and your scope eyepiece will automatically be centered on that object. You see the sky through the EZ Finder II viewing window the way it appears on star charts, making it easy to orient yourself on the sky. There’s no confusing mirror image or upside down view such as the one you see in a conventional magnifying finder. The brightness of the red dot is adjustable to suit your preference. Thumbwheels allow fine positioning of the dot horizontally and vertically for precise alignment with the main telescope. Focuser: 2” aluminum Crayford type, with removable 1.25” accessory adapter. The Crayford-style focuser has silky-smooth backlash-free motion that eliminates image shift, making it easier to achieve the sharpest possible focus. Eyepiece: A multicoated 25mm 1.25” Sirius Plössl is standard equipment. The 25mm eyepiece provides 48x, with a 1.08° field, more than twice the diameter of the full Moon, for expansive deep space views. Collimating tool: A pinhole-type collimating cap that fits into the focuser drawtube allows quick alignment of the primary and diagonal mirrors. If more precise alignment is desired, an optional battery-powered LaserMate laser collimator is available. The primary mirror is center-marked for easier collimation.
Software: Included is a special edition CD-ROM of Starry Night software. This is a very capable basic first step into exploring the night sky on your PC or Mac computer. You can use it to plan your observing sessions and print out star charts on your computer to take out with your telescope to explore with your own eyes the objects the program shows you.
This Telescope’s Mount . . . Dobsonian mount: The particle board Dobsonian altazimuth mount base has a triangular ground board (rather than circular) to reduce the weight of the base to only 20.7 pounds. The base has a convenient carry handle. The base is shipped disassembled and needs to be assembled only once, unless you disassemble it to save space for long-term storage. The assembly process takes about 30 minutes and requires no special tools. Altitude and azimuth bearings: The altitude bearings rest in ultra-high molecular weight (UHMW) polyethylene pads for smooth vertical motion. The azimuth bearing uses Teflon bearing pads for equally smooth “stiction-free” horizontal motion. CorrecTension balance system: The dual spring tension system applies the correct level of tension to the altitude bearings to balance the weight of different eyepieces. With the CorrecTension system, you can change eyepieces or add a Barlow lens without having to hold the tube in place in altitude by hand or tediously adjust the telescope’s balance with counterweights as you do with other Dobsonians when the eyepiece weight changes. This is particularly important with this scope, given its ability to use heavy 2” eyepieces.
What can you see though the Orion SkyQuest XT8 Classic? Under dark skies, the Orion Nebula becomes a glowing complex of filaments that more than fills the 1.08° field of the scope’s standard 25mm Sirius Plössl eyepiece. With over 800 times the light-gathering ability of even the sharpest dark-adapted eye, the SkyQuest XT8 Classic makes nebulas and galaxies stand out briskly and in surprising detail. Binary stars and clusters are often resolved almost to the core because of the scope’s very good resolving power. Messier, NGC, and IC objects show detail and structure never visible in smaller telescopes. As with any large aperture telescope, the performance of the 8” SkyQuest on faint objects will be markedly improved by a dark sky observing site. While usable from light-polluted city and suburban sites, such sites are not ideal as the primary observing site for an 8” scope. Such sites require a nebula (light pollution) filter to avoid having deep sky objects washed out by the glare of city lights. Within the solar system, the rings of Saturn are routinely visible with the standard 25mm eyepiece at 48x, as are lunar mountain ranges and craters by the hundreds. At optional higher powers, Cassini’s Division in Saturn’s rings is often resolved, while the ring system itself is a magnificent sight. Given suitably good seeing, Encke’s Division and other minor features in Saturn’s rings occasionally become visible, for example, as does the faint crêpe ring. Low contrast details in Sat
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