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STARTRACKER EXPLORE SCIENTIFIC G.S.O. Taiwan i-Optron GoTo Systems BRESSER Germany SKY-WATCHER Telescopes with
Motor & GoTo
GSO PRO-Dobsonian Telescopes

12inch Professional Dobsonian Telescope by GSO
D=304mm / F=1520mm Dobsonian F/5 - MADE IN TAIWAN Telescope
75000 + 18% GST
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Gaseous Giants  
The GSO Dobsonian line is particular model serves a very clear purpose, to offer a large aperture and an excellent image quality at reasonable cost.

Set-up is as easy as you can imagine very simple assembly with the rocker box and put it on the ground, insert the telescope tube and put the springs in position and you're ready to go to navigates through the night sky by simply moving the tube up or down, or side to side, by hand.

All GSO dobsonian use optical quality BK7 glass, cooling fans built into the rear cell to decrease cooling times, also all dobs use a roller bearing on the azimuth surface providing dozens of support points for smooth swivel motion. The deluxe model comes with 2" Micro 10:1 Crayford style focuser and 1.25" adapter.
Country of Manufacturing TAIWAN
Optical Design
Newtonian reflecing Telescope
Primary Mirror 12 inch Paraboli 1/12 wave.
Precisely figured parabolic mirror - diffraction limited / BK7
94% enhanced coating
Focal Length 1520mm
Focal Ratio F/ 5
Highest Practical Power 720
Faintest Steller Magnitude 14.7
Resolving Power
0.46 Arc - Seconds.
Focuser diameter 2" Precission Micro 10:1 Crayford style focuser".
With 1.25” eyepiece adapter. A Dual-Speed 10:1 ratio focuser is now included for excellent focusing precision. 
Eyepiece Standard 2" Premium Widefield SP 30mm (2")
68° field SuperView eyepiece with a wide 1.7° actual field of view that’s well over three times the diameter of the full Moon.
Eyepiece Standard 1.25"
Premium Plossl 9mm (1.25") 52° field.
Magnification with eyepiece 50.6x & 168.8x
Finder 8x50mm Fully multi-coated achromatic finder
Mount type
DOBSONIAN- wooden / with Roller Bearing wooden base / Clutch mount with tension knob
Mirror Cell
9 points mirror cell with cooling fan
Accessories Tray 2 inch Eyepieces tray
Mirror stabiliser Cooling fan for "thermal equilibrium"
Battery-operated primary mirror cooling fan
Total Height 63 inch
Tube length 60 inch
Stand height 27 inch
Base diameter 25.5 inch
Shipping Weight Tube : Net weight - 18 Kg / Gross weight: 20 Kg
Stand: Net weight - 13Kg / Gross weight: 15 Kg
Shipping Weight
Tube : 46 x 48 x 155 cm3
Stand: 15 x 74 x 74 cm3
Buy BAADER Solar Safety Film
Buy 1000 OAKS Solarite Safety Film
Instructions for use in ENGLISH
Download Instruction Manual of 254/1250 Dobsonian Reflector Telescope in .PDF format.
The following items are FREE with the telescope listed above.
Magnitude 5 STAR Atlas
Directional Compass  FREE
Collimination Tool (for Newtonian)
Micro Fiber (Anti-Static) Cleaning cloth
Optics Cleaning Fluid
COLOUR POSTER 17.5"  x 22.5 "  one
110 Messier Object Locator     A4 size front back colour print
109 Deep Sky CALDWELL Catalogue A4 size front back colour print
Star Dial - Identifying Stars & Constellations
Various Astronomical Post-Card (SET-3)
Desiccant Cap - Refillable desiccant cap to protect fine optics
Astronomical Telescope - user guide
The Moon Map Poster B/W chart unfold to 22"x26"
8x50 Finderscope
Powerful 8x50 finderscope, multicoated objective lens. This little telescope will show many objects in direct vision for easy location.
Finderscope Bracket
The 8 x 50mm finderscope mounts in a quick release bracket that slips into a pre-installed metal mounting shoe nearer the focuser. The bracket is held in place in the mounting shoe by a single large hand-tighten knob that maintains the finder’s collimation, even if the finder is removed between observing sessions. The bracket has two hand-adjust collimation screws that work in conjunction with a third spring-loaded post in the bracket. This makes collimation faster than the traditional three- or six-screw collimation methods used with conventional finder brackets.

Optical Quality
The heart 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 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.
Primary Mirror
12” (304mm) diameter, 1520mm focal length, f/5 focal ratio with surface accuracy of 1/12 wave. The mirror is made of B270 “water white” optical crown glass that is free of internal stress and striae. B270 glass is equivalent to BK7 in performance and optical quality. The thermal stability of B270 glass is generally better than the soda lime float glass used for the mirrors of most reflectors in this reasonable price range. The mirror is ground and polished under computer control for guaranteed diffraction limited performance, coated with 91% reflectivity aluminum, and overcoated with a protective layer of silicon dioxide (quartz) for long life.
Primary Mirror Cell
Fully adjustable 3-point flotation system metal cell holds the primary mirror. The open frame of the cell allows the mirror to cool down to ambient temperatures quickly, so you can start observing sooner. Large hand-tighten color-coded push-pull collimation and collimation lock knobs make it easy to collimate the primary mirror with no tools required.
Diagonal Mirror
70mm m.a. B270 “water white” optical crown glass, coated with 91% reflectivity aluminum and overcoated with a protective layer of silicon dioxide (quartz) for long life.
Diagonal Mirror Support
Fully adjustable diagonal holder mounted on a low-diffraction four-vane thin spring steel spider.

Two Eyepieces
Fully multicoated 2” 30mm (40x) 68° field SuperView Erfil design eyepiece with a wide 1.7° actual field of view that’s almost three and a half times the diameter of the full Moon.
The second is a fully multicoated high power 1.25” 9mm (133x) 52° field Premium Plössl eyepiece.

New Altitude Tension & Balancing System
This is another major improvement of this new altitude bearing system. The telescope can be balanced by moving it up or down a couple of centimetres. This may be necessary when adding or using very heavy eyepieces or a Camera. A scale on both sides allows you to easily achieve a symmetric bearing position.
Altitude Ball Bearings
Instead of the usual large circular trunnion bearings riding on a few Teflon pads in the semi-circular cutouts in the altazimuth base, the STAR TRACKER Dob uses innovative sealed metal ball-bearing systems to provide smooth vertical motion of the optical tube. The aluminum bearing housings fit snugly into cutouts in the sides of the altazimuth base. Because the bearings are sealed systems, the elements cannot affect the smoothness of the vertical motion, as it can when dust and grit invariably get trapped between the exposed trunnions and Teflon pads of conventional Dobsonians and scores the surfaces. The vertical motion of the STAR TRACKER tube is consistently ball-bearing smooth. And the sealed ball-bearings will not have to be replaced regularly, as is the case with the Teflon pads of many Dobsonians when wind-borne grit degrades the Teflon/trunnion interface.
Altitude Clutch
Large ribbed clutch knobs are built into the two altitude bearings. A gentle twist on either knob adjusts the amount of friction within the altitude ball-bearing systems. This allows you to keep the focuser from rising or sinking when changing between eyepieces of considerably different weights, as for instance when switching between 1.25” and 2” eyepieces.

Primary Mirror Cooling Fan
A lightweight 4.7” diameter low-vibration cooling fan is built into the mirror cell to assure faster cool-down times. The battery-operated fan is powered by a battery pack that uses eight user-supplied AA batteries and plugs into a jack on the mirror cell frame.

GSO 2" Dual Speed Crayford Focuser

The focuser is the most "visible" part of any telescope with the exception of the optics themselves. You touch the focuser all the time, the focuser is responsible for holding your eyepieces or camera in position and moving them precisely into focus in the first place. This way ultra-precise focus motion is possible for both visual and particularly photographical applications.

The features ::

  • The finest focuser GSO 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. 3kgs with a firm friction setting
  • 1:10 dual speed microfocuser for far improved focusing precision
  • 2" compression ring
  • 2" to 1.25" adaptor with compression ring and 2" filter thread

1. Smooth Focusing Action
The Crayford style focusing control makes achieving precise focus for visual observations and astrophotography a breeze and you will experience very smooth and precisely controlled focuser motion with zero backlash and zero image shift. 

2. High-Quality Construction and Features
CNC machined from aluminum and anodized black, this focuser comes with a base plate adapter to attach to reflector telescopes. The inner drawtube glides on 4 precision bearings and a roller shaft and provides. The inner barrel is baffled and painted a flat black to minimize reflections for maximum contrast.

The 2" focuser barrel features a brass compression ring so your eyepieces and other accessories will not be marred by the set-screw. Also included is a 1.25"-2" adapter with brass compression rings that is threaded to accept standard 2" filters.

The inner draw-tube barrel is anodized black and features a laser-etched scale.

3. Tension Adjustment and Focus-Lock
The focuser has two large thumbscrews on the underside. The thumbscrew on the telescope side can be used to lock the focuser, allowing the use of heavy accessories or cameras without fear or slippage or losing focus. The other thumbscrew on the eyepiece end can be used to adjust the tension of the focuser to achieve a focusing "feel" that you like. At the easiest (lightest) setting, the focuser moves extremely smoothly. At tighter settings, you can still use heavier accessories without sacrificing much of the smooth focuser action. GSO's rated load capacity for their Crayford focusers is about 3 kgs.

Eyepiece Tray
A standard equipment eyepiece tray attaches to the side of the scope’s altazimuth base. It has cutouts to hold one 2” eyepiece and three 1.25” eyepieces.

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.
Suggested Accessories with this Telescope
  • Baader Solar Filter (off-axis) Germany . . . . Rs. 2460
  • SOLARIX Solar filter (Explore Scienfific - USA) provide more pleasing and natural Yellow-Orange image of the Sun . . . . Rs 2730
    EYEPIECES (Super Premium Plossl for GSO) EYEPIECES (Super Premium Plossl for GSO)
  • 40mm Plossl Eyepiece 1.25" . . . . Rs. 2820
  • 32 mm Plossl Eyepiece 1.25" . . . . Rs 2640
  • 25 mm Plossl Eyepiece 1.25" . . . . Rs. 2550
  • 20 mm Plossl Eyepiece 1.25" . . . . Rs. 2460
  • 15 mm Plossl Eyepiece 1.25" . . . . Rs. 2280
  • 12 mm Plossl Eyepiece 1.25" . . . . Rs. 2100
  • 9 mm Plossl Eyepiece 1.25" . . . . Rs. 2100 (include)
  • 6 mm Plossl Eyepiece 1.25" . . . . Rs. 2100
  • 4 mm Plossl Eyepiece 1.25" . . . . Rs. 2100
  • GSO SuperView 15mm 1.25" Wide Angle Eyepiece . . . . Rs. 3000
  • GSO SuperView 20mm 1.15" Wide Angle Eyepiece . . . . Rs. 3000
  • GSO SuperView 30mm 2 " Wide Angle Eyepiece . . . . Rs. 4800 (include)
  • GSO SuperView 42mm 2" Wide Angle Eyepiece . . . . Rs. 4800
  • GSO SuperView 50mm 2" Wide Angle Eyepiece . . . . Rs. 4800
  • GSO 2x ED-Barlow-Lens (Multicoated) . . . . Rs.4800
  • GSO 2X Achromatic BARLOW LENS- fully multicoated 1.25" . . . . Rs. 1470
  • ED 3X Barlow Lens GSO 1.25" . . . . Rs. 2640
  • 3 Elememt 2.5x Barlow GSO 1.25"  . . . . Rs. 2370
  • 3 Elememt 5x Barlow GSO . . . . Rs. 2820
  • T-RING Nikon . . . . Rs. 840
  • T-RING Canon . . . . Rs 840
  • T Adapter 1.25" . . . . Rs. 750
  • Super ACHROMATIC (MultiCoated /High Colour corrected) 2X BARLOW 1.25" OD, 2 ELEMENT LENS with T-thread for direct camera attachment /with Brass compression ring / GSO. . . . Rs. 3,000
  • Eyepiece Projection Camera Adapter . . . . Rs. 2100
  • Mobile Cell Phone Adapter . . . . Rs. 1830
  • GSO 1.25" 32mm Camera Projection Lens (CPL) eyepiece ... Rs. 3,900
  • GSO 1.25" 40mm Camera Projection Lens (CPL) eyepiece ... Rs.4,080
  • GSO 2" 30mm Camera Projection Lens (CSV) eyepiece ... Rs.5,700
  • GSO 2" 42mm Camera Projection Lens (CSV) eyepiece ... Rs.5,700

  • Padded Carry Bag for 12 inch Dobsonian OTA . . . . Rs. 3900
  • GSO....0.5X Focal Reducer 1.25" with 25mm extension tube ....Rs 1560
  • GSO.....0.5x Focal Reducer 2 inch ....Rs 2100
  • GSO Planet View filter each . . . . Rs 660
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