GSO N 250/1250 deluxe Dobsonian telescope

Dobson GSO Deluxe

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GSO N 250/1250 deluxe Dobsonian telescope

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GSO 10-inch f/5 Dobsonian Telescope Deluxe Version

Join the growing number of happy users of GSO quality telescopes! We are very proud of GSO´s exceptional image quality at a very affordable price. Thousands of objects are within reach of this 10" Newtonian-style telescope.

With its highly refined Dobsonian style mount the telescope is the ideal companion for discerning beginners and for advanced observers alike! A 10" mirror will collect about 55% more light than an 8" mirror. This means that the image is much brighter, and many more objects are within reach. Galaxies will reveal their spiral structure. Planetary nebulae will display splendid detail where a smaller telescope will hardly show anything. The diffraction limited quality optics from GSO will at the same time offer razor sharp images even at high magnifications. Planets and the moon will be seen in great detail. The visibility of details is not limited by the telescope, but rather by observing conditions!

Optical Quality The centerpiece of any telescope is its optics. GSO produces parabolic primary mirrors of very high quality. It is our firm opinion that GSO offers better mirrors than typical in this price range. We guarantee a diffraction-limited performance, which essentially means that the performance is limited by observing conditions and the laws of physics rather than by the telescope itself!

GSO 2" Crayford Focuser: This is one of the best focuser this manufacturer has to offer. It is far superior to most classic rack-and-pinion focusers:

♦ no image shift when focusing

♦ large load capacity: up to approx. 3 kg with a firm friction setting

♦ 1:10 dual speed microfocuser for far improved focusing precision

♦ compression rings for 2" and 1.25" accessories 

New! Full metal secondary holder: Completely new developed was the secondary holder made out of metal. The secondary is safely glued onto the holder and not holded by plastic parts anymore. This prevents tensioning from changing temperatures.

Also, the holder guarantees the precise orientation of the secondary to the focuser, unintended twisting is not possible anymore.

New Altitude Tension & Balancing System: On most Dobsonian telescopes the altitude bearing is a very simple design. GSO has developed an improved altitude bearing with additional functionality: a strong steel shaft bears the weight of the tube. The tube is guided and kept in position through two CNC machined surfaces. The desired tension can be freely adjusted with a large knurled knob on both sides. This is particularly helpful when changing eyepieces where the telescope is temporarily out of balance.

Balancing System: This is another major improvement of this bearing system. The telescope can be balanced by moving it up or down a couple of centimetres. This may be necessary when adding a second finderscope (like a Telrad) or when using very heavy eyepieces or a binoviewer. A scale on both sides allows you to easily achieve a symmetric bearing position. 

Azimuth Roller Bearing: A simple teflon friction bearing used by some other manufacturers (also by GSO in the past) offers a rather stiff motion that makes tracking at high magnifications difficult. This becomes particularly obvious when the telescope is pointed near the zenith so that the lever arm becomes very short. In this position tracking is almost impossible in some Dobsonians!

The new GSO Dobsonians have a modern industrial roller bearing for a very easy movement. Metal plates above and below the bearing prevent the rollers from sinking into the softer wood of the rocker box, so the movement will remain smooth even after years of use.



Type Reflector
Type of build Newton
Aperture (mm) 250
Focal length (mm) 1250
Aperture ratio (f/) 5
Resolving capacity 0,46
Limit value (mag) 13,8
Light gathering capacity 1280
Max. useful magnification 500
Tube construction Full tube
Tube weight (kg) 15,5
Tube length (mm) 1210


Ventilation for central mirror yes
Primary mirror - Material BK7
Main mirror´s construction parabolic
Secondary mirror obstruction 25
reflectivity 94
Adjustable yes


Type of build Crayford
Connection ( to eyepiece) 2
Gear reduction 1:10 Fine movement


Type of build Dobson
Mounting type Dobson
GoTo control no
Tracking no


Material Wood
Type Rockerbox

Included accessories

1.25'' eyepieces 9mm
Finder scope 8x50
Eyepiece adaptor 1,25" - 2"
2'' eyepieces 30mm

Area of application

Moon & Planets yes
Nebulae & galaxies yes
Nature Observation no
Astrophotography not recommended
Sun not recommended (Only with appropriate Sun filter)

recommended for

Beginners yes
Advanced yes
Observatories no