Telescope-Service: GSO Dobsonian Telescopes

GSO Dobsonians

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GSO is one of today's well known premium quality manufacturers for Newtonians and Dobsonians. The telescopes have an excellent value for money and a quality comparable with other more expensive manufacturers.

Dobsonians are ideal for visual observers with no interest in astrophotography, but who wish to get the best out of their money in terms of visual performance.

Sooner or later all amateur astronomers face the same dilemma: They want the biggest telescope they can get their hands on (since, as they say, "Aperture can only be replaced by even more aperture"), but their finances draw the line terribly soon.

This is partially due to the inherent expenses for high-quality optics, but also due to the fact that a large telescope also requires a heavy - and expensive! - mount to carry it.

John Dobson (being in a monastery) faced a similar problem in the 1970's and therefore constructed and built several telescopes of a radically new design. To put it all in a nutshell, he cut out everything the telescope could spare and still remain a functional telescope. The result was the "Dobsonian telescope": A large Newtonian optical tube (Dobson actually ground and figured the mirrors himself!) mounted in what is little more than a box of wood. There are no fancy setting circles, worm gears or motor drives. You basically put all your money into big, good quality optics.

The result are very large aperture telescopes at a fraction of the cost of most conventional models!

The Dobsonian telescope design is by many considered to be the ultimate, no-nonsense telescope. It will show you extraordinary details in all fields of visual astronomy, especially deep-sky observations (that is: observations of faint objects like galaxies, gas nebulae and the like).

Still, you have to be aware that there is (in fact, that there must be!) also a limitation: Dobsonian telescopes are by design not suited for any kind of astronomical photography.

Fortunately there is a way to make your dobsonian telescope fit for astronomical photography. You take the optical tube and put it on an equatorial mount. The drawback: Obviously this means that you will need a big and heavy, and therefore expensive, mount to do that. Consider this whenever you want to buy a Dobsonian telescope and do not rule out astronomical imaging!



C-Line Dobsonians The GSO C-line Dobsonians offer an outstanding value for money and performance. The low prices are achieved mainly by cutting costs on the accessory side, the optical performance is not compromised!
200 / 1200mm	250 / 1250mm	300 / 1500mm

C-Line - Aperture 200mm / Focal Length 1200mm 2" focuser, good quality optics, top price offer	C-Line - Aperture 250mm / Focal Length 1250mm 2" Crayford focuser, 8x50 finderscope, 2" eyepiece	C-Line - Aperture 300mm / Focal Length 1500mm Excellent value for money 2" focuser, 8x50 finderscope, 2" eyepiece

GSO Truss Tube Dobsonians Above a certain size closed tube Dobsonians are no longer portable. The new GSO Truss Tube design solves this problem!
400 / 1800mm

Aperture 400mm / Focal Length 1800mm 2" Crayford focuser, 2" wide angle eyepiece, cooling fan, 8x50 finderscope, ...

Please send requests or online orders to: sales@telescope-service.com


GSO Dobsonian 200C - Aperture 200mm - Focal Length 1200mm A low-budget, excellent quality entry into the world of 20cm telescopes! Image: GSD 200 C - The GSD 200 E is similar in appearance, but has a different focuser. This image shows the smaller 6x30 finderscope. Now the Dobsonian comes with the larger 8x50 finderscope.

GSD 200E and C - Aperture 200mm - Focal Length 1200mm

Within our GSO Dobsonian line this particular model serves a very clear purpose: To offer a large aperture and an excellent image quality at as low a price as possible. The value for money is fabulous.

At the same time the optical and mechanical quality is at the same high standard that our customers have learned to respect in all GSO Dobsonians!

Innovative features like the primary mirror cooling fan and azimuth roller bearing top off the excellent package of our 8" GSO Dobsonian.

Gas Nebulae and Galaxies in Detail
With this telescope you will be able to see fine details in planetary nebulae - remnants of old, dying stars. You will see the spiral arms in many galaxies. Large nebulae like the Veil nebula in Cygnus can be seen with many beautiful details.

The Moon and the Planets
Sharp images of the moon and the planets require excellent optics. The GSO Dobsonian has a precisely figured parabolical primary mirror for superb images. The small secondary mirror and the four thin secondary spider vanes bring along even sharper and more detailed images than would be possible with a large secondary mirror that is held by three thick spider vanes.

Grab-And-Go Setup
The simple and intuitive way to use this telescope makes it much easier for beginners to spend their first joyful hours under the starry sky. Set-up is as easy as you can imagine: Just put the rocker box on the ground, insert the telescope tube and put the springs in position and you're ready to go!

Further Information: Visit our new Online Shop!

Recommended Accessories

Here you can find accessories that are important and helpful for almost any telescope. Cleaning tools, filters, star charts, ...

Please send requests or online orders to: sales@telescope-service.com


GSO Dobsonian 250C - Aperture 250mm - Focal Length 1250mm Economy line GSO Dobsonian with good 2" accessories GSD 250 C - a powerful and very affordable telescope not only for observing the deep sky objects, but also for observing the planets with high contrast.

Now the GSD 250 C comes with a good quality Crayford focuser for extra-smooth focus motion.

GSD 250 C

Why should you sacrifice quality only because you want to save money? The GSO Economy line was created to offer Dobsonian telescopes as cheap as possible without reducing the quality of the optics. In our opinion the result is an excellent telescope at an exceptional value for money.

Optical Performance

The telescope is equipped with the same high quality GSO parabolical primary mirror as the GSD 250 BCR and SCR. We guarantee a diffraction limited performance.

As a result you get sharp and contrasty images of the moon and the planets as well as impressive views of countless deep sky nebulae and galaxies. Many details can be seen in these nebulae.

Simple Operation

The telescope is operated with ease by a single person. The weight and dimensions are small enough to be handled by one person as well. The tube will fit on the back seats of most cars.

Using a Dobsonian is very simple. The telescope is moved manually around a horizontal (azimuth) and vertical (altitude) axis. An azimuth roller bearing and an altitude Teflon friction bearing are used to offer good motion smoothness.

Further Information: Visit our new Online Shop!

Recommended Accessories

Here you can find accessories that are important and helpful for almost any telescope. Cleaning tools, filters, star charts, ...

Please send requests or online orders to: sales@telescope-service.com


GSO Dobsonian 300C - Aperture 300mm - Focal Length 1500mm Economy line GSO Dobsonian with good 2" accessories GSD 300 C Dobsonian with good 2" accessories - the image shows an older model of the telescope with rack and pinion focuser. Now the telescope comes with a better Crayford focuser.

Optical Performance

The telescope is equipped with the same high quality GSO parabolical primary mirror as the GSD 300 BCR. We guarantee a diffraction limited performance.

As a result you get sharp and contrasty images of the moon and the planets as well as impressive views of countless deep sky nebulae and galaxies. Many details can be seen in these nebulae.

Simple Operation

The telescope is operated by a single person.

Using a Dobsonian is very simple. The telescope is moved manually around a horizontal (azimuth) and vertical (altitude) axis. Teflon friction bearings are used to offer good motion smoothness.

GSD 300 C

Why should you sacrifice quality only because you want to save money? The GSO C-line was created to offer Dobsonian telescopes as cheap as possible without reducing the quality of the optics. In our opinion the result is an excellent telescope at an exceptional value for money.

Further Information: Visit our new Online Shop!

Recommended Accessories

Here you can find accessories that are important and helpful for almost any telescope. Cleaning tools, filters, star charts, ...

Please send requests or online orders to: sales@telescope-service.com


GSO Truss Tube Dobsonian 400 TDI - Aperture 400mm - Focal Length 1800mm The Flagship of our GSO Dobsonian line: The GSD 400. The tube and rocker box are actually in black colour. For details please see our product presentation in our online shop!

The GSD 400 is the new TOP model in the GSO Dobsonian range.

400mm Aperture
With its enormous aperture of 400mm the GSD 400 shows myriads of deep sky objects in detail. You have nearly twice the light gathering power of a 300mm Dobsonian. Some objects will already begin to show colour. For example, the Great Orion Nebula will glow in a fascinating greenish hue.

Truss Tube Design
Above a certain size telescopes can no longer be considered portable. This sets an upper limit for the useful aperture of classic telescope designs. At the same time the old rule "aperture can only be replaced by even more aperture" dictates that a telescope should be as large as possible for maximum light gathering power.

The solution for this problem is the truss tube design. It allows you to split the telescope into smaller, more compact parts that can be transported more easily.

The new GSO Truss Dobsonians use this principle and thus offer a greater aperture than would be considered portable in a conventional tube design. On the whole the 400mm Truss Tube Dobsonian can be transported just as easily as the classic 300mm Dobsonians.

Altitude Friction System
The altitude bearing of the GSD 400 is made to compensate for great differences in eyepiece load. You can move the entire telescope up and down in order to find the best possible balance point. In addition you can adjust the friction to stop the telescope from moving involuntarily.

Further Information: Visit our new Online Shop!

Recommended Accessories

Here you can find accessories that are important and helpful for almost any telescope. Cleaning tools, filters, star charts, ...

Please send requests or online orders to: sales@telescope-service.com

Other Dobsonians

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