Ursa Major 6" and 8" Dobsonians share the same superb GSO parabolic mirrors as StellaLyra Dobsonians but have a more traditional Dobsonian base (Teflon pads & spring tensioner) single speed focuser and 'straight' finder-scope.
This has enabled us to achieve lower prices, making them an excellent choice for anyone starting astronomy.
About this product
Part Number: GS580-C
NEW updated model with robust azimuth roller-bearing assembly.
Designed and manufactured to a very high standard by Guan Sheng Optical (GSO) in Taiwan.
With 6" aperture, a long f/8 focal ratio and only 22% secondary obstruction, this easy-to-use Dobsonian telescope is an excellent choice for observing the Moon and planets.
In good seeing conditions, you can observe Mars with surface shading and polar cap. Jupiter's weather bands and several of its Moons, Saturn with its rings (including the Cassini division), and Venus and its phases are all visible.
Viewing the lunar surface will feel like you can reach out and scratch plaster!
The long focal length suits higher magnification visual observations. However, the 6" aperture and high contrast optics also provide excellent views of brighter deep sky objects like M42 / Orion Nebula or Galaxies like M81 and M82.
Ursa Major 6" and 8" Dobsonian telescopes are fitted with GSO aluminised parabolic primary mirrors with minimum 93% reflectivity and a silicon-dioxide protective overcoat to ensure the surface remains bright for years to come.
Collimation knobs on the primary mirror cell provide easy adjustment without tools.
This 6” model also features a surprisingly good CNC-machined (not cast metal) 1.25" Crayford focuser for smooth, accurate focusing and zero image shift.
Fully multicoated 1.25" 9mm and 25mm Plössl eyepieces are included so views will be clear and sharp, from the outset.
Teflon pads provide smooth altitude (up-down) movement, and tension can be adjusted to achieve the right amount of resistance. A spring tension system prevents the telescope from moving during eyepiece changes.
A robust roller-bearing assembly provides smooth, reliable azimuth (left-right) adjustments. Metal plates above and below the bearings prevent them from sinking into the softer wood (no divots!), so the movement remains smooth, even after years of use.
The Dobsonian base is delivered flat-packed and is easy to assemble.
- 152mm (6") Newtonian reflector optics
- 1200mm focal length
- f/7.9 focal ratio
- 22% secondary mirror obstruction
- Parabolic primary mirror with minimum 93% reflectivity
- Aluminium and silicon dioxide (SiO2) protective mirror coatings
- Sturdy primary mirror-cell with easy grip collimation knobs
- Rigid, steel telescope tube with 4-vane, all metal secondary Spider and adjustable primary cell
- CNC-machined 1.25" Crayford focuser with non-marring brass compression rings
- Smooth, stable Dobsonian mount with Azimuth tension adjustment, four slot eyepiece holder and front carry-handle
- Robust roller-bearing assembly provides smooth, reliable azimuth adjustments.
- Supplied with fully multicoated 1.25" 9mm and 25mm Plössl eyepiece
- 6x30 finderscope
Telescope Field of View Simulator
What's in the box
- 6" Newtonian Reflector Telescope
- Dobsonian Mount
- 6x30 Finderscope
- 1.25" 35mm Extension Tube
- 9mm 1.25" Super-Plossl Eyepiece
- 25mm 1.25" Super-Plossl Eyepiece
|Model ||6" f/8 Dobsonian |
|Optical design ||Newtonian Reflector |
|Aperture ||152mm (6") |
|Focal ratio ||f/7.9 |
|Focal length ||1200mm |
|Primary mirror ||BK7 Parabolic primary mirror, minimum 93% reflectivity |
|Mirror coatings ||Aluminum and silicone dioxide (SiO2) |
|Secondary mirror ||Minimum 93% reflectivity |
|Secondary mirror holder ||4-vane all metal spider |
|Secondary Mirror Obstruction ||22% |
|Focuser ||1.25" Crayford |
|Mount ||Dobsonian mount with spring tension control |
|Finderscope ||Straight through 6x30 |
|Eyepiece 1 ||9mm 1.25" 52º Super-Plossl with 6mm eye-relief |
|Eyepiece 2 ||25mm 1.25" 52º Super-Plossl with 22mm eye-relief |
|Tube outside diameter ||176mm / 6.9" |
|Tube length ||1100mm / 43.3" |
|Tube weight ||9kg / 19lbs 13oz |
|Shipped size OTA ||127cm x 36cm x 30cm / 50" x 14.2" x 11.8" |
|Shipped size Base ||63cm x 63cm x 14cm / 24.8" x 24.8" x 5.5" |
|Shipped weight OTA ||10kg / 22lbs 1oz |
|Shipped weight Base ||13kg / 28lbs 11oz |
Downloads / Manuals
Ursa Major 6" Dobsonian Assembly Manual
|Average Rating (2 Reviews): |The Ursa Major 6 inch, f/8, Planetary Newtonian
08 November 2023 | Prof
Purchased on a Tuesday morning, the tube assembly and flat pack Dobsonian base arrive by courier the next day. The assembly instructions for the base unit were downloaded from the FLO website and it was made up with little problem. Between the base plate and the rotating head are two metal plates which sandwich a roller bearing unit to provide very smooth azimuth rotation - a nice touch. The optical tube contains a parabolic mirror made by GSO (Guan Sheng Optical) who make the hyperbolic mirrors for virtually all the Ritchey-Chrétien telescopes sold today. Optically, as expected, it appears fine. The focuser is a very well made 1.25 inch Crayford type and is very smooth in use. Being only a 1.25 inch focuser rather than the 2 inch focusers found now on most new telescopes is actually a very good thing. As the maximum area that has to be illuminated is smaller than if a wide angle 2 inch eyepiece were to be used, the secondary mirror can be smaller and, in the Ursa Major, is just a 22% obstruction - as low as any Newtonian can have and so very little energy is diffracted out of the central Airy Disk into the surrounding rings providing a very high 'micro-contrast' so important when observing the planets. Two good quality Plössl eyepieces were provided as well as a 1.25 inch barrel extender. The 6x30 finder scope was mounted well away from the telescope tube and good to use. First light was that first evening with Jupiter rising in the east. The equatorial bands were easy to see as well as its 'point like' satellites. Io was very close to the limb of Jupiter and its clear visibility attested to the high overall contrast of the telescope's image. In all, an excellent telescope which is very well worth its cost. I bought it as a present for my grandson - but would quite like to keep it!
27 April 2022 | Paul
After much indecision I ordered the 6" Ursa Major from FLO, having found much advice on-line suggesting a 6" Dobsonian as a good first telescope. Ordering was painless and delivery only took a few days, including a Bank Holiday weekend. The OTA and base arrived separately packed, with the OTA securely double boxed.
As my first telescope, I was impressed with the quality - in particular the CNC machined focuser was very well finished and smooth in operation - and the optics appeared to be in full collimation. Assembly was straightforward using the downloaded instructions, although I would point out that the holes for securing the upper part of the mount to the base are not equidistant - something to check before trying to assemble.
I have only been out once with this, on a moonless night. Stars appeared sharp, with not too much in the way of diffraction spikes. Moving both sections together was easy; however, I found using the straight through finder a problem due to a bad back. I'm sure this would not be a problem for someone younger and fitter.
Overall, I think this would be an good telescope for someone like myself, new to astronomy. The low cost does not seem to be reflected in the quality provided and the issue I had was not down to the telescope itself.
Please fill in the form below to ask a question.
Q1. I would be very grateful if the dimensions of the base could be provided.
The base has a diameter of 49cm, and approx 67cm in height when fully assembled.