Sky-Watcher 20" Stargate Truss-Tube Dobsonian

  • Aperture: 20-Inch
  • Focal Length: 2000 mm
  • Focal Ratio: f/3.95
  • Focuser: Dual Speed 2-Inch Crayford
  • Best suited for: High-end visual observation


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  • Regular price $6,999.00

More on the Way* We do not currently have this in stock, but is a common item we carry. More are likely on the way as the manufacturer allows.
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Sky-Watcher 20" Stargate Truss-Tube Dobsonian


The Stargate 500P 20-Inch Truss Dobsonian:

Sky-Watcher has opened a portal to the stars with the new Stargate 20-Inch Truss-Tube Dobsonian telescope. This telescope was designed for immense light gathering power and ease of use, and is sure to deliver on both fronts for the most discerning of visual astronomers. With a maximum useful magnification of 1000x, you will find that the Sky-Watcher Stargate 20-Inch Dobsonian makes it easy and enjoyable to scour planetary and deep sky visual targets for the most refined and subtle of details. The Stargate 20-Inch is somewhat larger than its 18-inch sibling, but Sky-Watcher still estimates that it should take no longer than thirty minutes for an experienced astronomer to assemble and render it ready for observational use under normal circumstances.

And of course, it's not just raw power and convenience that Sky-Watcher prioritized when designing and making the Stargate 20-inch. They also made sure to include a primary parabolic mirror design that eliminates the spherical aberrations that are otherwise inherent in faster focal length reflectors. These mirrors are designed to bring all of the light your telescope has gathered to a single focal point and ensure sharp, high contrast, high detail images. Every optical mirror in the Stargate, including the parabolic primary mirror, is fully multi-coated with high quality Silicon Dioxide coatings that ensure optimal durability and performance.

 The Zenith Eyepiece Height for this system is 79-inches. It gathers and captures 56-percent more light than a 16-inch telescope. The Mirror coatings are 94-percent Aluminum. The Secondary Diameter is 134 mm minor axis.

Major Component Weights:

  • Dobsonian Base: 40-pounds
  • Mirror Box: 70-pounds
  • Truss Poles: 2.6-pounds each, about 16-pounds total
  • Upper Cage: 12-pounds
  • Counterweights: 2.3-pounds each, (3) 6.9-pounds total

When fully assembled without weights this item weighs 138-pounds.



AP14 inches and Larger (355+mm)
Aperture508 mm (20")
Dawes Limit0.23
FL 2499mm
Focal Length2000 mm
Focal Ratiof/3.9
FRf/4 or Faster
Free ShippingYes
Glass TypeBorosilicate
Limiting Magnitude16
Maximum Magnification1000X
Minimum Magnification72x
Optical DesignDobsonian
Secondary Obstruction7%


  • Sky-Watcher 20-Inch Stargate Dobsonian
  • 2-Inch Dual Speed Crayford Focuser with 1.25-inch and 2-inch Extension Tubes
  • 2-Inch 28 mm LET Eyepiece
  • 2-Inch 10 mm Eyepiece
  • 9 x 50 Straight-Through Finderscope
  • Cast Metal Rocker and Base with Teflon Bearings
  • 3 Counterweights, 2.3-pounds each
  • Clamps and Shroud