Sky-Watcher 20" Stargate 500P Truss Tube Dobsonian
- Fused conical primary mirror
- Cellular secondary mirror
- Dual speed 2” Crayford focuser
- Two section truss poles (compact transport)
- Minimalist, all metal construction
- Fast f/3.95 optics for short eyepiece heights
- 20” provides 56% more light than a 16” telescope
- 94% reflectivity coatings
- Superior quality optical elements
Sky-Watcher USA's superior optics just got better - the 20" Stargate 500P Truss Tube Dobsonian telescope features Sky-Watcher’s exclusive fused conical parabolic mirror. The fused design allows for thinner mirror construction that provides faster cooling and lighter weight. This is a breakthrough in Dobsonian-Newtonian telescope fabrication technique. The thinner precision parabolic mirror is supported by fused conical radial struts, thus providing the solid stability you require but greatly reducing the thickness and weight of the primary mirror. Faster cooling of the primary means you get to do serious observing earlier in the evening and for a longer time.
Combined with the cast cellular secondary mirror and Sky-Watcher’s exclusive 94% reflectivity coatings, the 20" Stargate 500P Truss Tube Dobsonian telescope delivers bright, detailed views of your favorite deep sky objects. The 20 inch (a full half meter of aperture) boasts a monster 56% more light gathering power than the S-W 16" scope.
Sky-Watcher uses a high-performance Teflon and steel 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 movements. Setting up this large Dobsonian scope is very simple and quick, and transporting it to your favorite site is also easy because it can be broken down into very manageable parts. See one of the photos for an illustration. For example, the primary mirror box weighs 70 pounds and the upper cage weighs only 12 pounds, while the Dobsonian base weighs only 40 lb.
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. The truss tubes are each disassembled into 36" long pieces which are easy to manage and transport. Adjustable feet make leveling a snap.
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. The minimalist all-metal structure of the Sky-Watcher 20" Stargate 500P Truss Tube Dobsonian 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. Azimuth and altitude bearings are steel and Teflon for smooth, steady movement. With the heaviest component being the primary mirror box, weighing 70 pounds, two persons can easily carry this part without back strain, and often one person who is physically fit may be able to carry the mirror box alone.
|Mirror Coatings:||94% Aluminum|
|Primary Aperture (mm):||508|
|Focal Length (mm):||2000 mm|
|Secondary Diameter:||134 mm|
|Secondary Obstruction (by diameter):||26%|
|Secondary Obstruction by Area:||7%|
|Dawes Limit:||0.23 arcsecond|
|Rayleigh Limit:||0.28 arcsecond|
|Light Gathering (compared to next size down):||23%|
|Focuser:||2" Dual-Speed Crayford Type|
|Upper Cage Weight:||12 lb|
|Truss Pole Weight:||2.6 lb, each, 16 lb total|
|Mirror Box Weight:||70 lb|
|Dob Base Weight:||40 lb|
|Full Assembled Weight:||138 lb, with weights|
|Zenith Eyepiece Height:||79"|
|Included Finder:||9 x 50|
|Included Eyepieces:||28 mm / 10 mm/ Collimating|
|Magnification w/ Included Eyepieces:||71x / 200x|
|Other Accessories:||3 ea 2.3 lb counterweight, Protective Shroud, Truss Clamps|