Astronomy Specialist




TESTAR Australia permanently hosts a fully assembled SkyWatcher Stargate 18" in its showroom in Sydney. 


The SkyWatcher Stargate 20" collapsible Dobsonian represents the ultimate combination between light gathering, precision and portability for outstanding performance and resolution. The truss structure is compact allowing for easy transport of this large telescope whilst looking for the perfect dark, pristine sky. The outstanding light gathering of the mirror and the superior resolution allows amazing journeys through the universe, offering spectacular observations of tangled gas filaments in nebulae, fine galaxy details and remarkable planet structures. Despite the size of the mirror, the telescope is easy to assemble following the step by step instructions and video.

To top it off, the SkyWatcher Stargate is equipped with a 2″ Crayford dual speed focuser for smooth and precise focusing and a focuser-locking screw.

The Freedom Find technology (dual-encoder) allows the telescope to be moved manually whenever the user wishes, but without losing any of the pre-set alignment.

Parabolic Primary Mirror

The most extraordinary feature of the Stargate is the technology used in the mirrors which are made up of borosilicate glass which has a very low expansion coefficient, reducing the stress caused by thermal gradients. The mirror is extremely light and thin but the glass ribs beneath minimise the glass deformation, thus allowing continuous high performance from all the telescope angulations. Also, the small thickness of the mirror allows a much quicker cooling time compared to the standard monolithic mirrors. The secondary mirror has a honeycomb structure that follows the concept of the primary mirror: lightweight, rigid and quick to cool down.

Both the mirrors are aluminised and in order to protect the reflective treatment over the years, the coatings are protected by a thin layer of quartz (silicon dioxide). This protection is needed as the mirrors are exposed to external elements due to their position in an open truss tube. Sky-Watcher is one of the few companies in the world that uses this particular technology.


Accessories in the box:

  • SynScan hand controller with cables
  • 12V power cable with lighter socket plug
  • Finderscope 9X50 straight version
  • Eyepiece 2″ LET 28mm (68x) – apparent field of view 56°
  • Eyepiece 1.25″ Super Plossl 10mm (190x) – apparent field of view 52°
  • Eyepiece adapter from 2″ to 1.25″ with M42 thread
  • 2″ tube extension
  • Collimation eyepiece
  • User manual



Optical design



508 mm

Focal length

2000 mm

Focal ratio


Secondary mirror

136 mm (minor axis)



Resolving power

0.24 arc seconds

Stellar limiting magnitude


Max magnification

1016 x

Light gathering power

5267 times the human eye


Crayford 2" dual speed




2 years on electronic components, 5 years on mechanical parts



  • SkyWatcher StarGate 20" Go-To
  • SynScan hand controller with cable (RJ45 to RJ45)
  • 12V power supply cable with lighter plug
  • Finderscope 9 x 50
  • Eyepiece adapter from 2″ to 1.25″ with M42 thread
  • Eyepiece 2″ LET 28mm (71x) – apparent field of view 56°
  • Eyepiece 1.25″ Super Plossl 10mm (190x) – apparent field of view 52°
  • User manual and SynScan manual



Video shot by Testar Australia

The SynScan go-to system is a computerized system supplied with the professional SkyWatcher mounts and telescopes. 

It features:

  • 9 speeds 1x, 2x, 16x, 32x, 64x, 128x, 400x, 500x, 600x, 800x (3.3°/sec)
  • 42,900 objects including planets, the moon, the sun, named stars, double stars, variable stars and the most famous catalogue that are Messier, Caldwell, NGC, IC & SAO 
  • Sidereal, moon and sun tracking speeds, 
  • Pointing Accuracy Enhancement feature (PAE)
  • Unknown Object Identification feature
  • Permanent Periodic Error Correction (PPEC) for mounts only
  • One, two and three stars or brightest star alignment (alt-azimuth telescope need at least 2 stars for the alignment)
  • Telescope parking feature
  • Polar allign procedure 
  • Deep Sky Tour function that suggests a list of the most interesting deep sky objects currently visible.

SkyWatcher SynScan 5

Download the SynScan user manual

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