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Sky-Watcher 8" Dobsonian

The 8" SkyWatcher Dobsonian provides what is now generally regarded as the minimum entry-level aperture for serious deep-sky observing in a poratable and affordable package. The low cost, large diameter, and fast focal ratio of the 8" Sky-Watcher Dobsonian make it an ideal dedicated telescope observation of faint galaxies, nebulae, and star clusters. At low-power this telescope dramatically captures wide swaths of sky in a single view. Galaxies and nebula appear to pop out of the heavens as bright, expansive masses of stars, gas, and dust.

Item #ProductStock StatusPriceShipping
S11700Sky-Watcher 8" Dobsonian
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Sky-Watcher Collapsible Dobsonian Telescope

Observing with the 8" Sky-Watcher Dobsonian

If you have never before observed through a high-quality, wide-field Dobsonian, like the SW 8" DOB, you are in for one of the sweetest experiences in amateur astronomy. Imagine the exhilaration of opening a clam and discovering a pearl. The sky is full of pearls, astronomical pearls. While they won't make you rich in the financial sense, for amateur astronomers at least, observing the fabled pearls of deep-space is a rich and even exhilarating pastime. A catharsis for the soul that renders the mundane insignificant, and reconnects us with the inner child who revels in awe and wonderment. A night observing with the SW 8" Dob can leave you with a lingering sense of contentment long after the evening's viewing is over. Some of amateur astronomy's most revered and enthusiastically observed extra solar-system objects are now within your reach. This instrumentation provides entry into the brotherhood of serious amateur astronomers—you have arrived!

The summer sky is aglow with astronomical pearls. In the constellation Sagittarius several of the sky's most prominent emission nebulae can be seen well in your 8" SW DOB. 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. The Lagoon Nebula appears fiery red in astrophotographs due to the hot hydrogen gas. Located nearby is the smaller, but very beautiful Trifid Nebula (M20). These two nebulae can actually be seen in the same field of view. The magnificent Swan Nebula (M17) is also located in Sagittarius. It is named the Swan for its resemblance to the stately bird. The sky's most awesome globular star cluster, M13, is located in the constellation Hercules, a bee-hive of thousands of stars swarming about a central core. Globular clusters are no longer being formed in the universe, so you are observing fossil light, a glimpse back in time. This is the brightest object of its kind and always a treat to view. The globular cluster M92 is likewise very interesting and can also be found in Hercules.

The winter sky holds several stunning pearls oft referred to in popular culture, not just astronomy. Our closest external galaxy, the beautiful Andromeda, perhaps the defining galaxy of the classic spiral form can essentially be seen almost in its entirety within one eyepiece field. Winter's diffuse Great Orion Nebula (M42) is the brightest emission nebula in the heavens. While it can be seen with the naked eye from a dark location, it is nothing less than spectacular in an 8" SW DOB. A billowing cloudlike cauldron of dust and gasses illuminated by large, intensely glowing youthful stars, this object is perhaps the mother of all pearls. The preceding is just a short sampling of objects that can be seen. Many more pearls of the night sky await you.

Sky-Watcher Dobsonians Epitomize Ease-of-Use

Observing with a Dobsonian has been described akin to shooting ducks in a gallery because it is so easy to find your target. Just swing your SW DOB to the quadrant of sky to be searched, and scan the vicinity. An 8x50mm Right Angle optical viewfinder provides both magnification and light-gathering to help narrow your search for those elusive fuzzies when star-hopping. The standard-equipment backlash-free 2" Crayford Focuser insures ultra smooth focusing adjustments. Multi-coated, 4-element Pl?ssl eyepieces (25mm and 10mm) provide a spacious 52? Apparent Field of View.

To ensure mechanical ease-of-use, SW uses a high-performance Teflon bearing system in both axes combined with tension adjustment in altitude to facilitate setting the appropriate amount of friction, assuring smooth vertical and horizontal manual movement without free-play from small bumps or gusts of wind. This also eliminates the need to have a balanced optical tube as in an equatorial mount. Sky-Watcher's Teflon bearing system is preferable to the use of ball-bearings. Ball-bearings make unintended movement of the optical tube more difficult to control. Fortunately, at low power, deep-space objects leisurely drift through the field of the SW 8" DOB, so constant mechanical adjustment of the telescope's orientation isn't needed to keep objects in the field of view.

Sky-Watcher's revolutionary truss-support concept allows the optical tube's front and back cells to collapse together, aligning on the truss support rods which can then be locked down for easy and secure telescope transport. This one piece, low-hassle OTA design is mechanically simple and results in large aperture telescopes that can be reasonably handled and transported by one individual. This innovation gives Sky-Watcher users tremendous functional ease-of-transportability.

Sky-Watcher Uses Quality Components Throughout

The Sky-Watcher 8" DOB utilizes quality components throughout. Pride of workmanship manifests itself in high quality standards of optical and mechanical fabrication. The polishing process for primary and diagonal mirror yields smooth mirror surfaces ensuring good contrast, and properly corrected optics show minimum alterations to the optical wave-front.

On each primary mirror, and elliptical diagonal mirror aluminum is vacuum deposited to the front glass surface and then over coated with hard quartz (SiO4). Additional layers of Titanium Dioxide (TiO2) and (SiO4) are then applied. Dust covers help keep your DOB clean when not in use.

The mechanical and structural components of the OTA exhibit rigid construction and outstanding stability. The mount construction is sturdy and rigid. Mount design, while simple, facilitates smooth motions about both axes. Quality accessories enhance the observer's viewing experience.

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Optical Specifications: Sky-Watcher 8" Dobsonian
Type Dobsonian
Aperture (mm) 200 mm
Aperture (in.) 8 inches
Focal Length 1200 mm
Focal Ratio f/6
Magnification (w/supplied eyepiece) 48X and 120X
Limiting Visual Stellar Magnitude <p><b>Limiting Stellar Magnitude</b><br />
This is a measure of the faintest star that can be seen with a telescope under ideal conditions.  We include this figure for the purpose of comparing two telescopes of different apertures using a consistent scale. Many manufactures publish this specification. Unfortunately manufactures use different methods to calculate this figure, rendering the numbers useless for direct head to head comparison of different brands of telescopes. </p>

<p>Limiting stellar magnitude is the sum of the naked eye limiting magnitude and the telescopic gain. The naked eye limiting magnitude varies by location due to local light pollution; therefore, it is an assumption.  This figure could be 6.5 or higher at some of the darkest locations, but less than 2 in the middle of a large city. Our calculations assume a figure of 5, which one might typically find 30-40 miles from a major urban area. </p>

<p>Telescopic gain is a direct function of aperture. No attempt has been made to compensate for the affects of central obstructions or different types of optical coatings.</p> 14.1 Magnitude
Accessories and Features
Finder 8x50 Right-Angle Optical
Included Eyepiece(s) 25mm and 10mm Plossl
Focuser 2-inch Crayford with 1.25-inch eyepiece adapter
Accepts 2" Eyepieces <p><b>Telescope Eyepiece Formats</b><br />
Virtually all telescope eyepieces available today conform to one of two barrel diameter standards: 1.25 or 2 inches. Most amateur astronomers will be perfectly content with 1.25" eyepieces. Two-inch eyepieces have only one inherent advantage. That advantage is a potentially larger field of view, but not every telescope can take advantage of that potential. </p>

<p>A Telescope and eyepiece work together to collect parallel light rays over a large area, compress those light rays down into a smaller area, and the re-orient them so that they are nearly parallel once again.  Essentially light arriving at a telescope with any given aperture is compressed into a smaller aperture or exit pupil.  The ratio of the telescope aperture to eyepiece exit pupil determines the magnification.</p>

<p>There are cases at very low magnifications where the eyepiece barrel diameter becomes the constraint on maximum field of view. The eyepiece barrel itself actually blocks some of the available light that the telescope is collecting, thus limiting the field of view.  Two-inch eyepieces overcome this constrain by allowing a larger light cone to enter the eyepiece. We must conclude this discussion by restating that 2" eyepieces have no inherent advantage over 1.25" eyepieces other than the potential for a larger field of view when used with a telescope capable of benefiting from that advantage. </p> Yes
Physical Parameters
Weight, Optical Tube 24.2 Pounds
Weight, Mount 25.3 Pounds
Weight, Fully Assembled 49.5 Pounds
Eyepiece Calculator
Enter your eyepiece's specifications:
Focal Length (mm):
Apparent Field (deg.):
 
Magnification:
 
True Field:
 
Exit Pupil: <p>Exit pupil represents the diameter of the column of light exiting the eyepiece.  Magnification is simply the ratio of telescope aperture to exit pupil.  Fox example, using a telescope with 100mm aperture and an exit pupil of 2mm yields a magnification of 50X.</p>

<p>There are both upper and lower limits to the useful range of exit pupils.  The typical human eye pupil dilates to a maximum of 7mm when fully dark adapted.  This figure decreases with age.  Using an exit pupil that is larger than this upper limit simply spills the light onto an area of the eye not capable of receiving data.  At the opposite end of the range, a smaller exit pupil means less area on the eye is collecting data.  Images brightness decreases with decreasing exit pupil. Deep space objects grow dimmer rapidly as the exit pupil falls below 1 mm. The planets also start to become noticeably dimmer when the exit pupil falls much below 0.5 mm.</p>

<p>Our eyepiece calculator provides warnings and error messages based upon the value of the exit pupil.  These are intended to be guidelines as opposed to hard rules. There is no harm in violating these gidelines, but your enjoyment of the telescope may be diminished if you do. </p>
 
 
Recommended Accessories: Sky-Watcher 8" Dobsonian
Item #NameDescriptionPrice 
AZ-1305Astrozap Light Shroud for 8" SkywatcherAstrozap Light Shrouds are made from light weight breathable black fabric. Two ABS bands prevent the shroud from sagging into and obstructing the light path the way competing products do.These shrouds block stray light and dew from reaching the optics.$59.00