This 8" Sky-Watcher Dobsonian reflector combines the proven "more light-gathering bang for your buck" economy of the Dobsonian telescope design with the exceptional convenience and portability of Sky-Watcher's unique telescoping truss-tube mechanical system.
This Sky-Watcher Dobsonian has:
• fully multicoated 8" f/6 Newtonian reflector optics
• unique telescoping truss-tube design for compact transportability
• smooth Teflon bearings, plus altitude tension control
• 10mm (120x) and 25mm (48x) 1.25" Plössl eyepieces
• 8 x 50mm right angle finderscope
With the 8" Sky-Watcher telescoping truss-tube Dobsonian, you don't have to worry about lifting the scope's diagonal mirror cage and trying to bolt it to three swaying truss tube in the dark as you do with other truss-tube Dobs. Sky-Watcher's revolutionary telescoping truss-tube system attaches the top of the truss tubes permanently to the diagonal mirror cage, with the bottom of the tubes sliding into three die-cast housings on the scope's primary mirror tub. This unique system allows the optical tube's diagonal mirror cage and three attached truss tubes to slide down onto the primary mirror tub to form one compact 32.5" long assembly. The cage and tub can then be locked together, using no-tool handles built into the primary mirror tub, and lifted out of the scope's altazimuth rocker base for easy and secure telescope transport.
Assembling the Sky-Watcher Dob for use involves simply unlocking the diagonal mirror cage and raising the cage until spring-loaded catches on the truss tubes snap into place in the primary mirror tub. This holds the cage at its fully-raised position while you tighten the no-tool handles at the base of the truss tubes to lock the diagonal mirror cage securely in position for observing.
For binoviewing without unwanted extra magnification, a second set of indents on the truss tubes allows the diagonal mirror cage to be lowered to a preset locking position on the truss poles. This lets you to use a binoviewer without needing a corrector or Barlow lens in the binoviewer to reach focus.
The complete Sky-Watcher telescoping truss optical tube assembly - diagonal mirror cage, integral truss tubes, and primary mirror tub - weighs only 24.2 pounds (11 kg). The altazimuth rocker box base it sits in weighs only 26 pounds (11.8 kg). Total weight is a light 50.2 pounds. When aimed at the zenith, the eyepiece is 45.5" above ground level.
The Sky-Watcher easily collapses in minutes into two small and light components that fit into a car trunk or into the back seat of a compact car. Competitive truss-tube Dobs break down into four or more components - diagonal mirror cage, primary mirror tub, altazimuth rocker box base, and truss tubes (as many as six to be carried separately or packed into an optional carrying bag). It's easy to see how the two-part Sky-Watcher has a definite convenience advantage over the four or more parts of a conventional truss-tube Dob. And, unlike bulky competitive solid-tube Sonotube or metal tube Dobs with an unwieldy 48" or 50" long optical tube, you don't need a big car to transport this 8" Sky-Watcher.
Assembly and disassembly take only about 5-10 minutes, with no tools needed. After you set up, particularly after traveling over bumpy roads to a dark sky site, take a few moments to check the collimation of the optics to assure peak performance and you are ready for an evening of fascinating viewing at your favorite dark sky location. The 8" Sky-Watcher telescoping truss-tube Dobsonian is designed for visual observing only - to show you as much of the night skies as possible, and do it as conveniently and inexpensively as possible. Photography is not possible with a Dob.
Because of its compact component size, light individual component weights, and limited number of components to put together (after all, there are only two!), the 8" Sky-Watcher telescoping truss-tube Dob can be transported and set up easily by one individual. This innovation gives Sky-Watcher users a cost-effective 8" telescope with unsurpassed compactness and transportability.
This Sky-Watcher Dob's Optical Tube Assembly . . .
Newtonian reflector optics: 8" diameter parabolic primary mirror, with 1.85" m.a. diagonal mirror. Both are guaranteed to be diffraction-limited. The diagonal mirror cage and primary mirror tub are made of rolled aluminum, anodized and finished externally with a subtle and attractive star-field pattern. Painted die-cast and machined rims hold the aluminum truss tubes and optical components in precise alignment to minimize the need for frequent collimation.
Primary mirror: Grade A annealed optical glass, 8" diameter, 1200mm focal length, f/6 parabolic in a fully adjustable metal cell provides sharp and bright high contrast images of nebulas, galaxies, and star clusters. The well-balanced f/6 focal ratio shows you subtle lunar and planetary details inside the solar system, as well. The center-spotted mirror is ground with computer-controlled accuracy, multicoated with aluminum and titanium dioxide for high reflectivity, and then overcoated with quartz for long life.
Diagonal mirror: Grade A annealed optical glass 1.77" m.a. diagonal mirror, mounted in a fully adjustable diagonal holder on a low-diffraction four-vane thin spring steel spider. The diagonal mirror is polished flat to diffraction-limited accuracy. As with the primary mirror, the diagonal is multicoated with aluminum and titanium dioxide for high reflectivity and overcoated with quartz for long life.
Finderscope: 8 x 50mm right-angle erect image achromatic crosshair design. The images in the finder are erect and right-reading, with star patterns looking just as you see them on star charts or with your bare eye. It is mounted near the focuser, with the finder eyepiece vertically aligned in the same direction as the telescope eyepiece. This eliminates the constant head twisting involved when switching between the horizontal orientation of a conventional Dob's straight-through or red-dot finder and the vertical orientation of its focuser and eyepiece.
Focuser: machined aluminum single-speed 2" Crayford focuser with a 1.25" eyepiece adapter.
Eyepieces: 10mm and 25mm 1.25" four-element Plössl eyepieces with a 52° apparent field. The 25mm provides a magnification of 48x with an actual field of view that is 1.08° across. That's more than twice as wide as the full Moon. The 25mm gives rich and expansive deep space views of star clouds, galaxies, and nebulas alike. The 10mm Plössl provides a stout 120x magnification with a 0.43° field of view, enough magnification to provide sharp close-up views of the Moon, planets, globular star clusters, and more.
Optical tube dimensions: Tube diameter (outside of one side bearing to the outside of the other bearing): 11.25"; tube length collapsed: 33"; tube length extended: 44".
This Sky-Watcher Dob's Base Assembly . . .
Rocker box altazimuth base: The altazimuth rocker box that the mirror tub rides in is crafted of strong, lightweight, and water-resistant laminated particle board, as is the water-resistant ground board that the rocker box rides on. The base is shipped disassembled, but can be put together in about a half an hour using only a screwdriver and the supplied hardware. Teflon bearings in both altitude and azimuth provide smooth and effortless motion of the optical tube in all directions. At the same time, the Teflon provides the proper amount of stiction to assure backlash-free movement, without the inadvertent and uncontrolled motions sometimes caused by wind gusts pushing on mounts using azimuth roller-bearings.
Navigation knobs: Two navigation knobs conveniently mounted on the diagonal mirror cage makes it easy to control the scope' motion in any direction. The optical tube starts moving at a gentle touch - smoothly and with no fuss. Center on an object and the scope settles down immediately, with no shudder or vibration to mar your viewing experience. The knobs also act as an aid in installing the optical tube into the base.
Carry handles/altitude tension control/eyepiece tray: The handles in the sides of the rocker box incorporate a tension control in altitude that lets you compensate for eyepieces of markedly differing weights. An eyepiece tray capable of holding one 2" and three 1.25" eyepieces attaches to the front of the rocker box above the supplied centrally-mounted carrying handle.
Altazimuth base dimensions: 20" in diameter by 29" high.
What can you see through the 8" Sky-Watcher telescoping truss-tube Dob?
Outside the solar system, the night sky is filled with fascinating objects within the reach of the 8" Sky-Watcher Dob. In the constellation Sagittarius lie several of the sky's most prominent emission nebulas. The Lagoon Nebula (M8) is a rich aggregation of dust and gasses illuminated by its youthful central stars. This is an area of star formation, the universe giving birth. Located nearby is the smaller, but very beautiful, Trifid Nebula (M20). The magnificent Swan Nebula (M17) is also located in Sagittarius. The sky's most awesome globular star cluster, M13, a bee-hive of thousands of stars swarming about a central core, is located in the constellation Hercules. This is the brightest object of its kind and is always a treat to view. Globular clusters are no longer being formed in the Milky Way, so in M13 you are observing fossil light, a glimpse back in time. Under dark skies, the Orion Nebula (M42) becomes a glowing complex of filaments, filling the wide 1.08° field of the standard eyepiece. Messier, NGC, and IC objects show detail and structure never visible in the smaller telescopes that are more common in this price range.
As with any serious telescope, the performance of the 8" Sky-Watcher telescoping truss-tube Dob on faint objects will be improved by a dark sky observing site. Heavily light-polluted city and suburban sites are not the best for observing very faint objects with any 8" scope.
Within the solar system, given suitably good seeing, Encke's Division and other minor features in Saturn's rings occasionally become visible in the 8" telescoping truss-tube, as does Saturn's faint crêpe ring. Low contrast banding and details in Saturn's atmosphere begin to make themselves apparent, as well. Lunar features less than one mile across become visible, while Jupiter's four Galilean moons start to show as tiny discs.
Taking advantage of the weight-saving sophistication of its telescoping truss-tube design, the 49.5 pound Sky-Watcher 8" Dobsonian makes it practical for one individual on his or her own to explore the heavens with a truly big scope, whether from a back yard or a distant dark sky observing site. This Sky-Watcher 8" telescoping truss-tube Dobsonian reflector will keep you happily observing for many years to come.
