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Sky-Watcher 20

Sky-Watcher Stargate truss-tube Dobsonians are the biggest thing to happen to the astronomy market in quite some time.


With the introduction of the 18 and 20 inch Stargate truss-tube Dobsonians, Sky-Watcher became the first telescope manufacturer to provide mass-market telescopes with this level of light gathering power. With this kind of aperture you’ll be able to view the most subtle planetary and deep sky phenomenon.

Stargate come complete with three 2.3 pound counterweights, 9×50 finderscope, two eyepieces (28mm, 10mm), collimation eyepiece, stabilizing clamps and ribbed fabric shroud.

Our superior optics just got better

Stargates feature Sky-Watcher’s exclusive fused conical parabolic mirrors. The fused design allows for thinner mirror construction that provides faster cooling and lighter weight.

Combined with the cast cellular secondary mirror and Sky-Watcher’s exclusive 94% reflectivity coatings, Stargate delivers bright, detailed views of your favorite deep sky objects. The 18 inch model captures 27% more light than our 16 inch, while the 20 inch (a full half meter of aperture) boasts a monster 56% more light gathering power.


Solid foundations, easy assembly

The minimalist all-metal structure of the Stargate produces a sturdy and stable platform while maintaining a convenient and compact footprint. The truss-tubes break down to a very manageable 36 inch length for easy transport. Azimuth and altitude bearings are steel and Teflon for smooth, steady movement.

Setting up a Stargate is a simple procedure, taking only about 20 minutes. Spring loaded truss anchor points are clearly labeled to eliminate any frustration or confusion. Adjustable feet make leveling a snap.


Synscan puts the universe in your hands

Our GoTo line of Stargates provide motorized operation in both alt and azimuth axes. Featuring Sky-Watcher’s proprietary SynScan hand controller, your scope now automatically slews to and tracks over 42,900 celestial objects from the on-board database.

Sky-Watcher’s Freedom Find™ dual-encoder technology ensures accurate tracking while allowing you to move the telescope manually in either axis without compromising alignment. This provides a level of convenience and flexibility not available in telescopes without dual encoders.



Optical Design Dobsonian
Primary Aperture (mm) 458mm (18”)
Secondary Diameter (mm) 120mm minor axis
Secondary Obstruction by Area 7%
Mirror Coatings 94% Aluminum
Glass Type Borosilicate
Focal Length (mm) 1900mm
Focal Ratio 4.1
Light Gathering (compared to next size down) Captures 27% more light than a 16” telescope
Zenith Eyepiece Height 74.5”
Rayleigh Limit 0.31
Dawes Limit 0.25
Limiting Magnitude 15.9
Minimum Magnification 65x
Maximum Magnification 902x
GoTo No
Focuser 2″ Dual Speed Crayford
Included Eyepieces 28mm LET eyepiece and 10mm eyepiece
Included Finder 9×50
Other Included Items 2.3lbs counter weights (3), Shroud, Truss clamps
Upper Cage Weight 11lbs.
Truss Pole Weight 2.6lbs each. 16lbs total
Mirror Box Weight 62lbs.
Dobsonian Base Weight 40lbs.
Fully Assembled Weight (with weights) 129lbs.

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