GSO Dobson: GSD 680

Unboxing | Assembly | Look | Basic Data | First Photo Attempts | 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" ...). 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.

 

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

The ingredients of my eyepiece case (eye pieces, filters, Barlow lens) can be used with this telescope as well.

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
GSO
8" 10" 12" 16" ETX 90EC 102 76 100P 114P P130 GSD 680
Optical Design Newton
(Parabolic)
Newton
(Parabolic)
Newton
(Parabolic)
Newton
(Parabolic)
Maksutov-Cassegrain Maksutov-Cassegrain Newton (Spherical) Newton (Parabolic) Newton
(Parabolic)
Newton (Parabolic) Newton (Parabolic)
Primary Mirror Diameter 203 mm 254 mm 305 mm 406 mm 96 mm (90 mm) 102 mm 76 mm (3") 100 mm (4") 114 mm (4.5") 130 mm (5") 200 mm (8")
Focal Length, Focal Ratio 1219 mm
f/6
1270 mm
f/5
1524 mm
f/5
1829 mm
f/4.5
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
1200 mm
f/6
Resolving Power (arc secs) 0.56" 0.45" 0.38" 0.28" 1.3" 1.15" 1.51" 1.15" 1.01" 0.9" 0.58"
Limiting Visual Stellar Magnitude ca. 14 mag ca. 14.5 mag ca. 15 mag ca. 16 mag 11.7 mag 12.7 mag 11.2 mag 11.8 mag 12.1 mag 13.3 mag 14.5 mag
Maximum Practical Visual Power ca. 550 x ca. 600 x ca. 700 x ca. 900 x 325 x 204 x ca. 100 x (152 x) 150 x (200 x) 170 x (228 x) ca. 220 x (260 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 51 cm x 170 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
23 cm x 115 cm
Net Weight Basis 9 kg 12.2 kg 15 kg 24 kg 3.5 kg (complete) --- 1.75 kg (complete) 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 33.6 kg 1.9 kg 1.2 kg*
(2.5*/2.8 kg complete)
3.7 kg
(5.3 kg complete)
3.25 kg*
(< 6.5 kg or 14 lbs. complete)
9.5 kg
(appr. 21 kg complete)

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...).

       

 

First Conclusions

My first impression of the GSD 680 telescope is very positive, even if it is based almost exclusively on observations of the Jupiter and the Orion Nebula in poor conditions. I believe that I have never seen both so well with my telescopes. 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, but it is too early for any reports here...

All in all, I do not regret buying the telescope, although it is, being an 8" telescope, still a bit too heavy for me... Mabye, I will switch to 6" one day. A light 6" scope might perhaps be put on my Star Discovery AZ GoTo Mount...

 

Links

 

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28.02.2017