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Explore Scientific - Generation II - 20-inch Truss Tube Dobsonian Telescope - DOB2036-00



The ideal workhorse for the deep sky observers, the Explore Scientific 20-inch f/3.6 Truss-Tube Dobsonian is our largest aperture telescope. The 500mm mirror collects 5100 times more light than the naked eye. Details on planets and deep sky objects will be visible even for inexperienced observers. Bright star clusters are resolved to the core, and the sight of the terminator on the moon is an unforgettable experience.

The fast 20" f3.6 main mirror as well as the large 120mm secondary mirror are made of high quality quartz material, so the cooling time is reduced to a minimum and this Dobsonian is quickly ready for use. Every main mirror is delivered with an individual optical test certificate, which guarantees the highest capacity. A laser engraved center mark of the main mirror allows easy adjustment. The optical surface has a high-quality aluminum coating with 94% reflectivity and an extremely resistant quartz protection layer. The mirror overcomes frequently occurring dew fogging and cleanups without damage and guarantees a long service life.

No telescope type has changed the hobby quite as much as the Dobsonian. Before the introduction of the Dobsonian by John Dobson, the vast majority of amateur telescopes consisted of small telescopes with primitive mechanics - barely enough to see the polar caps of Mars or the rings of Saturn. Larger telescopes, such as the Schmidt-Cassegrain were reserved for the wealthy. The ingenious combination of simple yet effective mechanisms with the greatest possible opening gives the Dobsonian telescope a unique triumphant march around the world. Nowhere do you get as much light for your money like a good Dobson. Disassembly of the scope without tools ensures a trouble-free transport of this great scope even in small cars. The entire structure has been optimized for maximum stiffness with minimal weight. The combination of high altitude bearings with optimized aluminum structures allows fine adjustment flows at high magnifications.

A complete redesign of this Dobsonian was necessary to ensure the significantly increased requirements to stiffness and load bearing capacity of the optical components. All connections of the tube structure were made in the TIG welding process and no rivets and screws were used. This has made it possible for us to produce this 20" light weight Dobsonian so unbelievably stiff in spite of the low weight - a noticeably good quality which is begging you to take one home. The production of almost all mechanical components is carried out by our partners in Hungary and the final assembly of the optics and subsequent quality control takes place in Rhede, Germany. 

A second 40° displaced installed mounting plate with a viewfinder shoe allows the rotation of the tube top in combination for a favorable position of the viewfinder tube or the mounting of an additional TELRAD viewfinder. The 6 supporting feet underneath the rocker box offers perfect stability and guarantees smooth tracking in azimuth. Four smaller fans are installed in the side of the mirror box as well as a large fan installed under the main mirror. This allows an even quicker adaptation to the ambient temperature and reduces the tube seeing (boundary layer removal). The lateral altitude wheels can now be stowed comfortably in the foam layers of the mirror box.

Includes 2.5" HEX focuser with helical gearing and 10:1 reduction; LED Red Dot Finder, collimation assist tool; soft light baffle and two radial main mirror fans for fast temperature equilibrium.

The scope is ready for the use with our optional coma corrector.




Item Number DOB2036–00
Secondary Obstruction 24%
Primary Mirror Diameter 500mm
Secondary Mirror Diameter (M.A.) 120mm
Focal Length 1826mm
Focal Ratio f/3.6
Total Height 70.5"
Total Width and Length 27"
Total Weight of Telescope 116 lbs


Limited Warranty is one year, which converts to the Explore STAR Transferrable Product Warranty when product is registered within 60 days of purchase. Click Here to register.

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18 reviews
Imaging Made Easy

Prism is my GoTo program for observatory control and imaging. Prism's many features make imaging taking a breeze.

I was concerned about giving Prism a try , especially as its quite expensive. So far Im very impressed and glad of my decision.
Im a beginner at all this so haven't tried other more recommended software, Prism appealed as it seems to do everything instead of using several programs 👍🏻

Great lightweight guide scope

This guide scope replaces a 400/80 that was waaay too heavy for what it did. The smaller 60mm scope does a great job guiding and I can RA balance with just one counter weight now - much better - and it looks like something Ferrari designed

Still learning Prism using Wireless links...

I have much of your software working at this time... I have it parked on my main computer, and a notebook... My main computer is a OverClock computer with 32 Gigs of RAM Clocking presently at 4400MHz with software parked on SSD drives... The rotation dome by NexDome is still not working... Most problems like this have to do with ASCOM Drivers... There is not very much detail information on how to use this software... I have to feel my way to a total operational staus... Second issue... The rain in the San Francisco Bay Area this year has limited my access to my larger telescope (12 inch SCT)... This rain has been so significant, I was force to weatherize my observatory... My goal here is,,, I am trying to remotely control my observatory totally. I have used Netgear Powerline 2000 to handle camera images and discover controlling rules to do that... High speed is vital for images with cameras over 3 Megs... I have both 12 Mega sensors and 24 Mega sensors... I am also using Netgear Nighthawk router and its mating extender to increase control signals to my observatory that is about 100 feet on the side of hill... I am also using Virtual Here software on a Raspberry Pi inside the observatory to solve the USB interface requirements... I started out using Model B and B+ on level 3 raspberry Pi's... I have moved to Level 4 Raspberry Pi to gain access to USB 3.0 technology... Big difference! I hope by early spring to have everything working... Bob Ritter MicTechS

A great program, even for beginners!

I have to admit, I was hesitant to invest in an “all in one” astrophotography program. Being a beginner, I thought the learning curve would be way too steep, but after talking with several friends I decided to give it a try. The first thing I noticed was the logical layout of the main screen. It was very intuitive and easy to navigate. Everything you could need for astrophotography is in this program! Setup of my equipment was quick and easy with no glitches or errors. Everything runs smoothly from capture to the final process. You will surely have questions and this brings me to the next point. Prism’s customer service is second to none! With on line tutorials, a Facebook group and email you will have instant access to knowledgeable users worldwide. My first question was answered directly by the US distributor within a matter of minuets! Take the next step and invest in your future in astrophotography! You’ll never look back!

Greg Hemmings