GSO Dobson: GSD 680

Unboxing | Assembly | Look | Basic Data | First Photo Attempts | Visited Sky Objects | First Conclusions | Links

On this page I present some information about my new "big" telescope, a GSO GSD 680 Dobsonian Telescope with 8" aperture (purchased end of March, 2016). It is the" De Luxe "version of the GSO 200C Dobsonian telescope.

As I have read many times, the 8 "Dobsonian telescope with f/6 (i.e., 1200 mm focal length) is nowadays the "classic "entry telescope for the more ambitious hobbyists. Some will stick to it for a lifetime, but many others are addicted aperture, and will buy larger and larger telescopes. I have no idea how I will deal with this (I'm actually on the "backward" movement from 10 "to 8" to 6"...). Previously, the 6 " Dobsonian with f/6 (i.e., 900 mm focal length) was the starter drug, but that seems to have changed...

Note: Seems to be more or less identical to the Bresser Revelation 8" f/6 M-CRF Premium Dobsonian telescope.

Note: I bought a 6" Newton tube in April 2017, because the GSD 680 was still too heavy for me. I gave it to a dealer to sell it for me. I therefore can no longer report any experiences with this scope here.

 

Unboxing

Boxes

Boxes (including box for Telrad finder)

Boxes (including box for Telrad finder)

Boxes

Tubus box

Tubus box:
Weight (measured): 16.6 kg (15 kg, 13 kg Net weight acc. to box)
Size (measured): 140.5 (L) x 41 (B) x 34 (H)

Rockerbox box:
Weight (measured): 13.2 kg
Size (measured): 69.5 (L) x 59 (B) x 13.5 (H)

(A dealer lists a total gross weight of 40 kg for the telescope)

Weights:
Tubus: 11.1 kg (measured) including finder scope
Rockerbox: 10.6 kg (measured) without eyepiece holder

Sizes:
Total height from floor: 1.32 m
Diameter rockerbox: 49.5 cm
Height rockerbox: 70 cm

Rockerbox Unboxing

Parts of the rockerbox in the box...

...and outside of the box

eyepiece holder (not used by me)

The manual was hidden in the tubus box ...

Rockerbox parts put together before the assembly...

...and with parts unpacked.

The metal disks, that is, the roller bearing plates, go between the two wooden disks, that is, the base plates.

Tubus Unboxing

The opened tubus box

Ditto

Ditto

The complete tubus can be seen now

Tubus without plastic foil

Empty tubus box

Boxes with accessories and more...

The 8 x 50 finder scope

Box with eyepieces, side bearings, and more

Accessories unpacked

The side bearings

Accessories: 9 mm and 30 mm eyepiece; 8 x 50 finder scope

In addition, I bought: Telrad finder and deep sky atlas

 

Assembly

Rockerbox Assembly

Note: I did not assemble the rockerbox in an optimum order. Only one day later, I found a video demonstrating the assembly of the 10" version: www.zhumell.com/telescopes/dobsonian/z8-dobsonian-telescope (Zhumell version; scroll the page for the video)

Ground base plate with attached plastic feet

Ground base plate with roller bearing plates and plastic roller bearing

Roller bearing put together with center bearing bushing attached

To base plate from below; the screws for fastening the wood base are already in place. There are no holes for screws to fasten the front brace...

The front brace before attaching the plastic handle...

... and afterwards

Now the side panels have to be attached to the top base plate. This was somewhat fiddly to do and to photograph...

Now the side panels are in place but the screws are not yet tight.

Finally, the front brace is added and all the screws are tightened.

Another view...

View of the nearly finished upper part of the rockerbox

And another view...

Now the two base plates need to be placed above each other. First, the roller bearing has to be put on the ground base plate and the roller bearing bushing added.

Then the top part of the rockerbox is carefully put on top of all this (see next photo).

Here, the upper part of the rockerbox is in place, and I need to add the adjustment bolt and two washers

The adjustment bolt and the two washers in detail

The adjustment bolt and the two washers in detail

The assembled rockerbox - I did not attach the eyepiece holder

Weights:
Rockerbox: 10.6 kg (measured) without eyepiece holder

Sizes:
Diameter rockerbox: 49.5 cm
Height rockerbox: 70 cm

 

Attaching the Side Bearings to the Tubus

Side bearings before attachment

First side bearing attached

Ditto

Second side bearing

Tubus with side bearings attached

Tubus from below with fan and collimation screws (main mirror)

 

 

Look

Final Assembly

Tubus in rockerbox

Tubus in rockerbox - turned

Tubus in rockerbox - from the side

Side bearings in use (wrong position)

Finder Scope mounted

Securing the tubus against bumps (not delivered...)

Crayford focuser with adapter for 1,25" eyepieces

Crayford focuser with 9 mm Plössl eyepiece (1,25")

Ditto; you can see the two screws for fixing the focuser.

Crayford focuser with 30 mm Erfle eyepiece (2")

Ditto

Size comparison (1,70 m vs. 1,32 m)

The next Day Outside...

Comparison with Heritage P130 and Heritage 100P

Size comparisons with Sky-Watcher Heritage 100P and Heritage P130

 

Basic Data for GSD 680 Telescope (in Comparison)

Telescope
Meade
Sky-Watcher Skymax/Heritage/Explorer
GSO
8" 10" 12" ETX 90EC 102 76 100P 114P P130 150PDS GSD 680
Optical Design Newton
(Parabolic)
Newton
(Parabolic)
Newton
(Parabolic)
Maksutov-Cassegrain Maksutov-Cassegrain Newton (Spherical) Newton (Parabolic) Newton
(Parabolic)
Newton (Parabolic) Newton (Parabolic) Newton (Parabolic)
Primary Mirror Diameter 203 mm 254 mm 305 mm 96 mm (90 mm) 102 mm 76 mm (3") 100 mm (4") 114 mm (4.5") 130 mm (5") 150 mm (6") 200 mm (8")
Focal Length, Focal Ratio 1219 mm
f/6
1270 mm
f/5
1524 mm
f/5
1250 mm
f/13.8
1300 mm
f/12.7
300 mm
f/3.95
400 mm
f/4
500 mm
f/4.38
650 mm
f/5
750 mm
f/5
1200 mm
f/6
Resolving Power (arc secs) 0.56" 0.45" 0.38" 1.3" 1.15" 1.51" 1.15" 1.01" 0.9" 0.77" 0.58"
Limiting Visual Stellar Magnitude ca. 14 mag ca. 14.5 mag ca. 15 mag 11.7 mag 12.7 mag 11.2 mag 11.8 mag 12.1 mag 13.3 mag 12.7 mag 14.5 mag
Light Gathering Power 841 1316.7 1898.5 165.3 212.3 117.9 204.1 265.2 344.9 459.2 816.3
Maximum Practical Visual Power ca. 550 x ca. 600 x ca. 700 x 325 x 204 x ca. 100 x (152 x) 150 x (200 x) 170 x (228 x) ca. 195/220 x (260 x) ca. 225 x (300 x) ca. 300 x (400 x)
Optical Tube Dimensions (diam. x length) 28 cm x 115 cm 35 cm x 119 cm 40 cm x 144 cm 10.4 cm x 27.9 cm 10.4 cm x 27 cm n.a. 11.5 cm x 37 cm* n.a. Tube collapsed < 37 cm
(14.5") long
18.2 cm x 69 cm
18 cm x 68 cm*
23 cm x 115 cm
Net Weight Basis 9 kg 12.2 kg 15 kg n.a. --- n.a. 1.3 kg* 1.6 kg 3.1 kg* -- 11.2 kg
Net Weight Optical Tube 10.9 kg 17.2 kg 21.3 kg n.a. 1.9 kg n.a. 1.2 kg* 3.7 kg 3.25 kg* 5.0/6.0 kg
5.5 kg*
9.5 kg
Net Weight Complete 3.5 kg 1.75 kg 2.5*/2.8 kg 5.3 kg < 6.5 kg or 14 lbs. appr. 21 kg

Dark Blue: Telescopes that I still own; italic and dark red: telescopes that I owned; black: for comparison; *) own measurement

 

First Photo Attempts

Jupiter with Moons (April 7 & 10, 2016)

The following photos were taken with the projection method (camera lens mounted fix to a 32mm eyepiece, ISO 3200) using a Leica X Vario (the rightmost photo is from April 10, 2016):

Jupiter (April 7, 2016)

The following photos were taken with the 1:50 method (camera lens held at an 9 mm eyepiece) and a Leica X Vario (ISO 3200). The photo sections were scaled down to 50% (looks better than 100%). Click the photos to see the sections at 100%.

Original Post-Processed Converted to B&W   Original Post-Processed Converted to B&W
 
 
 

The following sections were scaled down to 25%, which makes them look even better:

Original Post-Processed Converted to B&W   Original Post-Processed Converted to B&W   Original Post-Processed Converted to B&W
   
   

Moon (April 10, 2016)

Photos with 32 mm DigiScope Eyepiece (Projection Method)

For the following moon photo attempts, I mounted the Leica X Vario fix to the 32 mm DigiScope eyepiece. The telescopic magnification was only 37.5 x, the camera lens was set to a focal length of 70 mm (46 mm actual) (I think...).

   

Enlarged Sections (100%):

 

Photos with 16 mm Eyepiece (1:50 Method)

For the following moon photo attempts, I held the Leica X Vario to the 16 mm eyepiece (1:50 method). The telescopic magnification was 75 x, the camera lens was set to a focal length of 70 mm (46 mm actual) set (I think...).

       

 

Visited Sky Objects

So far, I have visited (and documented...) the following sky objects with the GSO GSD 680:

This list is probably incomplete, because I did not document my observations well. But, at least, it shows, which objects can be found with this telescope. In addition, this telescope should be able to access all those sky objects that I listed for my smaller telescopes.

 

First Conclusions

My first impression of the GSD GSD 680 telescope was very positive, even though it was based almost exclusively on observations of the Jupiter and the Orion Nebula under poor conditions. I believe that I had never seen both objects so well with my other telescopes as with the GSD 680. In the meantime, I was also able to observe and take photos of the moon, which surprised me pleasantly. I also was able to look at a few bright deep sky objects in summer/autumn 2016 and in spring 2017. Here, my impression was also very positive, although the number of observed sky objects was very limited that I visited with this telescope.

All in all, I do not regret having bought the telescope, although, as an 8" telescope, it is regrettably still too heavy for me... Maybe, I will switch to a 6" tube one day. A light-weight 6" telescope might perhaps also be used on my Sky-Watcher Star Discovery AZ GoTo mount...

Supplement

In the meantime (early April 2017), I bought a 6" Newton tube, a Sky-Watcher Explorer 150PDS 150 mm / 750 mm (f/5), and it makes a good impression on me. I've also used it on the Sky-Watcher Star Discovery AZ GoTo mount, but this seems to be a "borderline case " - I do not know whether the engine and the gearbox will last long under this heavy load. But it does work at the moment...

I did a first "quick comparison" with the 6" Explorer 150PDS tube using the targets M 42/43 and M 35 (April 9, 2017). Since my eyepieces do not allow me to use both telescopes with the same magnification in parallel, such a comparison is, of course, problematic. All in all and not surprisingly, the view through the GSD 680 looked brighter and more contrasty to me, but the Explorer PDS150 was not bad either. I was actually prepared to sell the GSD 680 because it is too heavy for me. But this comparison made me somewhat undecided... In the end, however, I decided to separate from the GSD 680, as nice as it is, because it is definitively too heavy for me, will give to a dealer to sell it for me.

 

Links

 

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gerd (at) waloszek (dot) de

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04.05.2017