 GSO Dobsonians |
| 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! |
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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! |
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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 |
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BCR / SCR Line Dobsonians
These Dobsonians have the same great optical performance of the economy line, but have more and better accessories. |
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Aperture 200mm / Focal Length 1200mm
2" Crayford focuser, 2" wide angle eyepiece, cooling fan, 8x50 finderscope, ... |
Aperture 250mm / Focal Length 1250mm
2" Crayford focuser, 2" wide angle eyepiece, cooling fan, 8x50 finderscope, ... |
Aperture 300mm / Focal Length 1500mm
The Flagship of our GSO Dobsonians: 2" Crayford focuser, 2" wide angle eyepiece, cooling fan, 8x50 finderscope, ... |
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GSO Truss Tube Dobsonians
Above a certain size closed tube Dobsonians are no longer portable. The new GSO Truss Tube design solves this problem! |
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Aperture 400mm / Focal Length 1800mm
2" Crayford focuser, 2" wide angle eyepiece, cooling fan, 8x50 finderscope, ... |
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Please send requests or online orders to: sales@telescope-service.com
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GSO Dobsonian 200E and C - 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. |
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| 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 The Moon and the Planets Grab-And-Go Setup Further Information: Visit our new Online Shop! |
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| Recommended Accessories |
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| Here you can find accessories that are important and helpful for almost any telescope. Cleaning tools, filters, star charts, ... |
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Please send requests or online orders to: sales@telescope-service.com |
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GSO Dobsonian 200 BCR - Aperture 200mm - Focal Length 1200mm High quality accessories: 2" Crayford focuser, wide angle eyepiece, roller bearing, ...  |
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Gas Nebulae and Galaxies in Detail The Moon and the Planets Grab-And-Go Setup GSD 200 - Aperture 200mm - Focal Length 1200mm |
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| Using the Dobsonian Mount The mount of a Dobsonian telescope is called "Rocker-Box", a fitting name for the uniquely simple and well-working design. The rocker allows you to point the telescope at any point in the sky and allows for comfortable, intuitive movement. Moving the telescope is very simple, just push the telescope into the right direction – no need to use clamps or motors, it doesn't get more simple than this! Despite its simple design you will be able to track objects precisely even at high magnifications. With a little experience 250x is no problem at all. Back-Focus The Dobsonian was designed for visual applications. It is sometimes not possible to find focus with SLR cameras. In such cases we recommend to refit the telescope with the low profile Crayford focuser. Some eyepieces with a low field stop might need to be pulled out of the focuser by a little margin in order to reach focus. If you do not wish to do that you can buy the optional 35mm extension tube. |
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Specifications:
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 The active cooling fan reduces cool-down time of this telescope significantly. |
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| Excellent Crayford 2" Focuser & Red. 1.25" - with 1:10 microfocuser the Crayford focuser has zero image shift and offers very smooth focus motion. Including 1.25" adaptor. Both 2" and 1.25" with brass compression ring...... further information |
High Quality Accessories & Eyepiece Tray |
8x50 Finderscope with Quick Release Bracket The achromatic objective is multi-coated for a brighter image. |
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| Thin 4-Vane Spider - More Contrast The less diffraction the better the contrast. Thin secondary spider vanes improve contrast compared with cheap three vane or thick four vane spiders - important for the moon and the planets |
Industrial Roller Bearing for Azimuth - Not Just a Simple Friction Bearing The roller bearing makes moving the telescope in azimuth much easier. If you want more friction simple felt pads will do the trick. |
Spring Tension System The spring tension system prevents the telescope from moving on its own when exchanging eyepieces. |
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 Optional Tube Rings |
GSO Dobsonians are no one-way street! Dobsonian telescopes are ideally suited for visual use - with no other telescope design will you get this amount of observing fun for your budget! Astronomical imaging on the other hand is barely possible with any Dobsonian telescope. Only the very brightest objects (the sun with the proper filter, the moon, the brightest planets) can be photographed without a tracking motor. Deep-sky objects (galaxies, gas nebulae) require long exposure times and consequently a solid equatorial mount. Two Telescopes in One Our idea was quite simple: As long as you desire just to enjoy the beauty of the various celestial objects and joyful hours behind your eyepiece you should set up the GSO Dobsonian as it is - as a Dobsonian telescope. Setup takes only a few seconds and you will be observing in no time. Also, this combination is very portable. For astronomical imaging or the comfort of a tracking motor just attach the cradle rings and put the tube on an equatorial mount. (see image to the left) Our recommendation: The Celestron ADM is a solid mount that will carry your 200mm "Newtonian" with good stability. For astro-imaging we offer a well working dual axis motor-drive. This combination will bring much joy to your astrophotographical ambitions. More details on the ADM Many other interesting mounts can be found here. |
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| Primary Mirror Substrates BK-7 and Suprax The image quality itself is not affected by the mirror substrate. Likewise cooldown-time is nearly the same regardless of which of these substrates you choose. The integrated cooling fan shortens the cool-down time considerably. The only difference between the mirrors is the image quality during cool-down (between 15 and 45 minutes, depending on the ambient temperature). BK-7 reacts about twice as strongly as Suprax. This means that you can use higher magnifications sooner with a Suprax mirror. Suprax has roughly comparable thermic properties as Pyrex. Once cool-down is complete there is no difference in optical quality. |
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Useful Links:
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Eyepieces
A broad selection of 1.25" eyepieces can be used with this telescope. |
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| Recommended Accessories |
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| Here you can find accessories that are important and helpful for almost any telescope. Cleaning tools, filters, star charts, ... |
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The TS Eyepiece and Accessory Case isn't just an assortment of randomly picked eyepieces, we have put a lot of thoughts into choosing a fine range of eyepieces that will work with nearly all telescopes. These great eyepieces are included in the TS eyepiece and accessory case: - three excellent quality TS Super Plossl eyepieces - one TS wide angle eyepiece - our excellent TS Barlow lens (2x/1.5x) - five carefully chosen TS colour filters and one grey moon filter (not just a cheap green filter) - an adaptor for focal and eyepiece projection astro-imaging All comes in a beautiful, foam-lined aluminium case .......... Link to further information |
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Please send requests or online orders to: sales@telescope-service.com |
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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. |
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 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 Simple Operation |
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Further Information: Visit our new Online Shop!
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| Recommended Accessories |
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| Here you can find accessories that are important and helpful for almost any telescope. Cleaning tools, filters, star charts, ... |
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Please send requests or online orders to: sales@telescope-service.com |
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GSO Dobsonian 250 BCR - Aperture 250mm - Focal Length 1250mm With an aperture of 250mm this telescope is a very popular combination of light-gathering power and portability.  |
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10 inches (250mm) of aperture make this telescope a Deep-Sky big gun. The TS WA 30mm 2" wide angle eyepiece offers a far larger true field of view than is possible with any 1.25" eyepiece. That is particularly important for viewing gas nebulae and galaxies. The secondary mirror obstruction is around 25%. This means that the GSD 250 is also well suited for lunar and planetary observations. Under good seeing conditions you will see plenty of craters, ridges and mountain ranges on the moon in finest detail. Planets, too, will make for innumerable joyful observing hours. You will see finest structures in Saturn's rings and many surface details on Mars. The telescope's large aperture brings along much easier to see colours, e.g. on Jupiter. The 12mm Super Plossl eyepiece which is in the standard scope of delivery offers an excellent contrast. Despite all the telescope can easily be handled by one person - it will fit on the backseats of most small cars. The GSD 250 is another sample of what I call "astronomical plug and play". Set-up and collimation take less than five minutes for experienced amateurs, you can launch into the observing session right away. Please see the General Notes on Dobsonian Telescopes to find out why a Dobsonian might be just the telescope for you! |
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| Using the Dobsonian Mount The mount of a Dobsonian telescope is called "Rocker-Box", a fitting name for the uniquely simple and well-working design. The rocker allows you to point the telescope at any point in the sky and allows for comfortable, intuitive movement. Moving the telescope is very simple, just push the telescope into the right direction – no need to use clamps or motors, it doesn't get more simple than this! Despite its simple design you will be able to track objects precisely even at high magnifications. With a little experience 250x is no problem at all. Back-Focus The Dobsonian was designed for visual applications. It is sometimes not possible to find focus with SLR cameras. In such cases we recommend to refit the telescope with the low profile Crayford focuser. Some eyepieces with a low field stop might need to be pulled out of the focuser by a little margin in order to reach focus. If you do not wish to do that you can buy the optional 35mm extension tube. |
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Specifications:
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The active cooling fan reduces cool-down time of this telescope significantly. |
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| Excellent Dual Speed 1:10 Crayford 2" Focuser the Crayford focuser has zero image shift and offers very smooth focus motion. Including 1.25" adaptor. Both 2" and 1.25" with brass compression ring...... further information |
High Quality Accessories & Eyepiece Tray |
8x50 Finderscope with Quick Release Bracket The achromatic objective is multi-coated for a brighter image. |
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| Thin 4-Vane Spider - More Contrast The less diffraction the better the contrast. Thin secondary spider vanes improve contrast compared with cheap three vane or thick four vane spiders - important for the moon and the planets |
Industrial Roller Bearing for Azimuth - Not Just a Simple Friction Bearing The roller bearing makes moving the telescope in azimuth much easier. If you want more friction simple felt pads will do the trick. |
Spring Tension System The spring tension system prevents the telescope from moving on its own when exchanging eyepieces. |
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Optional Tube Rings |
GSO Dobsonians are no one-way street! Dobsonian telescopes are ideally suited for visual use - with no other telescope design will you get this amount of observing fun for your budget! Astronomical imaging on the other hand is barely possible with any Dobsonian telescope. Only the very brightest objects (the sun with the proper filter, the moon, the brightest planets) can be photographed without a tracking motor. Deep-sky objects (galaxies, gas nebulae) require long exposure times and consequently a solid equatorial mount. Two Telescopes in One Our idea was quite simple: As long as you desire just to enjoy the beauty of the various celestial objects and joyful hours behind your eyepiece you should set up the GSO Dobsonian as it is - as a Dobsonian telescope. Setup takes only a few seconds and you will be observing in no time. Also, this combination is very portable. For astronomical imaging or the comfort of a tracking motor just attach the cradle rings and put the tube on an equatorial mount. (see image to the left) Our recommendation: The EQ-6 is a solid mount that will carry your 250mm "Newtonian" with good stability. A photographical variant of this mount is available. It offers a better tracking precision. This combination will bring much joy to your astrophotographical ambitions. More details on the EQ-6 |
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| Primary Mirror Substrate BK-7 The image quality itself is not affected by the mirror substrate. Likewise cooldown-time is nearly the same regardless of which of these substrates you choose. The integrated cooling fan shortens the cool-down time considerably. The only remaining difference between different mirror substrates is the image quality during cool-down (between 30 and 45 minutes, depending on the ambient temperature). BK-7 reacts about twice as strongly as Suprax or Pyrex. However, this is only one side of the truth. The other side is that warm air will rise from the still warm mirror and cause "local seeing" that affects the image even more. It doesn't matter whether the mirror is made of BK-7, Suprax or solid gold - it will always suffer from this effect until it is fully cooled down. Considering how expensive exotic mirror substrates are we favour a cooling fan rather than "better" substrates! |
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Useful Links:
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Eyepieces
A broad selection of 1.25" eyepieces can be used with this telescope. |
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| Recommended Accessories |
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| Here you can find accessories that are important and helpful for almost any telescope. Cleaning tools, filters, star charts, ... |
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The TS Eyepiece and Accessory Case isn't just an assortment of randomly picked eyepieces, we have put a lot of thoughts into choosing a fine range of eyepieces that will work with nearly all telescopes. These great eyepieces are included in the TS eyepiece and accessory case: - three excellent quality TS Super Plossl eyepieces - one TS wide angle eyepiece - our excellent TS Barlow lens (2x/1.5x) - five carefully chosen TS colour filters and one grey moon filter (not just a cheap green filter) - an adaptor for focal and eyepiece projection astro-imaging All comes in a beautiful, foam-lined aluminium case .......... Link to further information |
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Please send requests or online orders to: sales@telescope-service.com |
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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. |
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Optical Performance Simple Operation 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. |
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Further Information: Visit our new Online Shop!
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| Recommended Accessories |
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| Here you can find accessories that are important and helpful for almost any telescope. Cleaning tools, filters, star charts, ... |
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Please send requests or online orders to: sales@telescope-service.com |
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Der GSD 300 bietet durch seine große
Öffnung spektakuläre Ausblicke ins All. Observing with the GSD 300 Fine structures in galaxies and gas nebulae are visible that are otherwise only seen in photographs. Objects even begin to show colour! In galaxy clusters you will be able to see several galaxies in your field of view, each of the galaxies consisting of billions of stars. Globular clusters are resolved to the center in single stars. Fine filaments can be seen in supernova remnants like the veil nebula. Under good seeing conditions the telescope will show splendid details also on the moon and planets. The cassini division in Saturn's rings is an easy target, as are fine structures in Jupiter's atmosphere and on Mars' surface. You only need to consider that with 300mm aperture the performance is often limited by turbulences in our own atmosphere - the telescope itself is not the limit to what you can see! Operation is still possible by a single person. For transportation you will need a station wagon or SUV at least, but the single parts are light enough to be carried by one person. Setting up the telescope is very easy and done within minutes. |
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| Using the Dobsonian Mount The mount of a Dobsonian telescope is called "Rocker-Box", a fitting name for the uniquely simple and well-working design. The rocker allows you to point the telescope at any point in the sky and allows for comfortable, intuitive movement. Moving the telescope is very simple, just push the telescope into the right direction – no need to use clamps or motors, it doesn't get more simple than this! Despite its simple design you will be able to track objects precisely even at high magnifications. With a little experience 250x is no problem at all. Back-Focus The Dobsonian was designed for visual applications. It is sometimes not possible to find focus with SLR cameras. In such cases we recommend to refit the telescope with the low profile Crayford focuser. Some eyepieces with a low field stop might need to be pulled out of the focuser by a little margin in order to reach focus. If you do not wish to do that you can buy the optional 35mm extension tube. |
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Specifications:
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 The active cooling fan reduces cool-down time of this telescope significantly. Note the 9-point flotation mirror cell! |
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| Excellent dual speed (1:10) Crayford 2" Focuser the Crayford focuser has zero image shift and offers very smooth focus motion. Including 1.25" adaptor. Both 2" and 1.25" with brass compression ring...... further information |
High Quality Accessories & Eyepiece Tray |
8x50 Finderscope with Quick Release Bracket The achromatic objective is multi-coated for a brighter image. |
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| Thin 4-Vane Spider - More Contrast The less diffraction the better the contrast. Thin secondary spider vanes improve contrast compared with cheap three vane or thick four vane spiders - important for the moon and the planets |
Industrial Roller Bearing for Azimuth - Not Just a Simple Friction Bearing The roller bearing makes moving the telescope in azimuth much easier. If you want more friction simple felt pads will do the trick. |
Spring Tension System The spring tension system prevents the telescope from moving on its own when exchanging eyepieces. |
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 Tube rings Made in Germany - they are made of birch plywood and offer an excellent stability and even vibration dampening properties. |
GSO Dobsonians are no one-way street! Dobsonian telescopes are ideally suited for visual use - with no other telescope design will you get this amount of observing fun for your budget! Astronomical imaging on the other hand is barely possible with any Dobsonian telescope. Only the very brightest objects (the sun with the proper filter, the moon, the brightest planets) can be photographed without a tracking motor. Deep-sky objects (galaxies, gas nebulae) require long exposure times and consequently a solid equatorial mount. Two Telescopes in One Our idea was quite simple: As long as you desire just to enjoy the beauty of the various celestial objects and joyful hours behind your eyepiece you should set up the GSO Dobsonian as it is - as a Dobsonian telescope. Setup takes only a few seconds and you will be observing in no time. Also, this combination is very portable. For astronomical imaging or the comfort of a tracking motor just attach the cradle rings and put the tube on an equatorial mount. (see image to the left) |
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| Primary Mirror Substrate BK-7 The image quality itself is not affected by the mirror substrate. Likewise cooldown-time is nearly the same regardless of which of these substrates you choose. The integrated cooling fan shortens the cool-down time considerably. The only remaining difference between different mirror substrates is the image quality during cool-down (between 30 and 45 minutes, depending on the ambient temperature). BK-7 reacts about twice as strongly as Suprax or Pyrex. However, this is only one side of the truth. The other side is that warm air will rise from the still warm mirror and cause "local seeing" that affects the image even more. It doesn't matter whether the mirror is made of BK-7, Suprax or solid gold - it will always suffer from this effect until it is fully cooled down. Considering how expensive exotic mirror substrates are we favour a cooling fan rather than "better" substrates! |
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Useful Links:
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Eyepieces
A broad selection of 1.25" eyepieces can be used with this telescope. |
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| Recommended Accessories |
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| Here you can find accessories that are important and helpful for almost any telescope. Cleaning tools, filters, star charts, ... |
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|
The TS Eyepiece and Accessory Case isn't just an assortment of randomly picked eyepieces, we have put a lot of thoughts into choosing a fine range of eyepieces that will work with nearly all telescopes. These great eyepieces are included in the TS eyepiece and accessory case: - three excellent quality TS Super Plossl eyepieces - one TS wide angle eyepiece - our excellent TS Barlow lens (2x/1.5x) - five carefully chosen TS colour filters and one grey moon filter (not just a cheap green filter) - an adaptor for focal and eyepiece projection astro-imaging All comes in a beautiful, foam-lined aluminium case .......... Link to further information |
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Please send requests or online orders to: sales@telescope-service.com |
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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. |