Sky-Watcher 10" f/4.7 Flextube 250P telescoping truss-tube Dobsonian

With the 10" 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 tubes 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 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 in 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 10" Sky-Watcher optical tube assembly - secondary mirror cage, truss tubes, and primary mirror tub - weighs only 33 pounds (15 kg). The altazimuth rocker box base it sits in weighs only 27.5 pounds (12.5 kg). Total weight is only 60.5 pounds, light for a full-sized 10" telescope. When aimed at the zenith, the eyepiece is 48" 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 - secondary 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 10" 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 10" 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 10" 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 10" telescope with unsurpassed compactness and transportability.

This Sky-Watcher Dob's Optical Tube Assembly . . .

Newtonian reflector optics: 10" diameter parabolic primary mirror, with 2.3" 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, 10" diameter, 1200mm focal length, f/4.72 focal ratio parabolic in a fully adjustable metal cell provides sharp and bright high contrast images of nebulas, galaxies, and star clusters. Lunar and planetary images are also sharp and crisp, but a neutral density (Moon) filter would certainly be called for to cut down on the incredible solar system brightness provided by this 10" mirror - over 1300 times that of the human eye. 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 2.24" 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 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): 13.5"; tube length collapsed: 31.5"; 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 knob: A navigation knob conveniently mounted below the focuser 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.

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 10" Sky-Watcher telescoping truss-tube Dob?

In viewing deep-space, aperture matters - big time! With the 10" Sky-Watcher, you have tremendous light gathering power to see faint and distant nebulas and galaxies - over 1300 times that of your unaided eye. Under dark skies, the Orion Nebula becomes a glowing and subtle complex of filaments, and color starts to become visible. The spiral structure of the Whirlpool Galaxy becomes apparent, as do dark dust lanes across the nucleus of the Andromeda Galaxy (although the full 3° width of the galaxy itself is far too large to fit into the field of view of any eyepiece generally usable with the scope). Globular clusters are frequently resolved to the very core. Messier, NGC, and IC objects show detail and structure never visible in smaller telescopes.

Many challenging objects for an 8" aperture scope now come into their own with the 10" Sky-Watcher. The Crab planetary nebula (M1), a supernova remnant, requires a 10" aperture to truly begin to appreciate its subtle, gaseous filamentary structures. M33, the low surface brightness face-on spiral galaxy in the constellation Triangulum, exhibits significantly more open arm structure than is visible in an 8" scope. The Rosette Nebula in Monoceros begins to show the pattern of a blooming rose that gives the Rosette its name.

There is no question that the increased resolving power and 56% greater light-gathering power of a 10" aperture is visually impressive when compared to an 8" scope. Therefore, it is no wonder then that the 10" aperture is overtaking the 8" as the serious amateur astronomer's aperture of choice in a Dobsonian telescope. Sky-Watcher's compact, telescoping optical tube design makes the decision to step up in aperture to a 10" scope even easier.

As with any large aperture telescope, the performance of the 10" Sky-Watcher on faint objects will be markedly improved by a dark sky observing site. Light-polluted city and suburban sites are not recommended as the primary observing site with a 10" scope. Such sites require a nebula (light pollution) filter to take even limited advantage of its immense light-gathering.

While it is in deep space observing of galaxies and nebulas from a dark sky observing site that the 10" Sky-Watcher telescoping truss-tube Dob excels, significant planetary and lunar observing is also within its capability. All you need is a neutral density eyepiece filter to cut down the immense brightness of solar system objects seen through this "light bucket."

Taking advantage of the weight-saving sophistication of its telescoping truss-tube design, the 60.5 pound Sky-Watcher 10" 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 10" telescoping truss-tube Dobsonian reflector will keep you happily observing for many years to come.

• Telescoping no-tool assembly truss tube design
• Rolled aluminum /die-cast secondary mirror cage and primary mirror tub
• Navigation knob
• Laminated altazimuth mount with Teflon bearing surfaces and altitude tension control
• 4-vane spring steel diagonal mirror support with adjustable mirror holder
• Adjustable primary mirror flotation system
• Diffraction-limited Grade A optical glass mirrors
• Protective primary mirror cover
• 2" Crayford-style machined aluminum focuser with 1.25" eyepiece adapter
• 25mm (48x) and 10mm (120x) 1.25" Plössl eyepieces
• 8x50mm right angle finderscope.