Orion SkyLine 6″ Review

written by Zane Landers
TTB score


The Good

  • Great Optics
  • Nice Focuser
  • High-Quality Included Eyepieces
  • Easy To Use

The Bad

  • Finderscope Is Uncomfortable To Aim
  • A Bit Heavy
  • More Expensive Than Some Other 6” Dobs
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The Orion SkyLine 6” is one of the best 6” Dobsonians out there and provides good value for the price and high-quality optics and components. 


The Orion SkyLine 6” is one of the best 6” Dobsonians out there and provides good value for the price and high-quality optics and components. It’s much better than cheaper telescopes with plastic focusers, small aperture, and often poor-quality mounts, accessories, or optics. The SkyLine 6” is manufactured by GSO and thus available under a variety of different labels, such as Apertura’s DT6, sometimes at lower prices or with different regional availability. These scopes are all the same apart from slight accessory differences so our comments in this review apply to the SkyLine 6” and its various copies equally.



152mm (6”) Aperture

1200mm Focal Length


The Orion SkyLine 6 is a 6” (152mm) f/7.9 Newtonian reflector with a focal length of 1200mm.

A 6” f/8 primary mirror is very easy to manufacture, deviating from spherical only slightly as a parabola. As such, manufacturers of scopes like the Orion SkyLine 6 are able to make them very accurately and the mirrors tend to suffer from very few hiccups in quality; they are usually very smooth and well-made. The SkyLine 6 provides razor-sharp views and achieving them is easy thanks to the scope’s Crayford focuser and well-designed collimation system, which doesn’t require any tools for adjusting the primary. The secondary mirror requires a hex key to adjust for collimation by default, and this is probably the way you should leave it.

While only a 1.25” focuser, the Crayford focuser on the SkyLine 6” is high-quality and much better than the cheap plastic rack-and-pinion or helical focusers found on most 6” and smaller aperture instruments sold to beginners. A 2” focuser and eyepieces would weigh down the front end and require a bigger secondary mirror, and in any case are a bit overkill for this telescope anyway. The Crayford focuser on the SkyLine 6” uses no lubricant or gears, and has multiple tension adjustments – you can set an overall minimum amount of friction with a hex key (helpful if you almost always use heavy eyepieces) and then adjust the tension – or simply lock the focuser in place – with two small thumb screws. 





Most Dobsonians manufactured by commercial entities have tiny altitude bearings, which make the scope easy to move but also allow for the center of gravity to rapidly shift outside of them and cause the scope to tip over when a heavy eyepiece is used. Other manufacturers solve this problem with a simple brake clutch that keeps the scope in place at the expense of stiff and jerky motions, or with bearings that can slide along the tube. Orion uses spring-tensioning on many of their Dobsonian telescopes such as the SkyLine 6 to keep the scope balanced with most eyepieces and provide smooth motions. The scope is easy to aim and stays put when you let go of it, and you should have no trouble tracking manually even at 300x magnification.



The SkyLine 6 includes:

Two 1.25” Plossl eyepieces – a 25mm (48x) and 9mm (133x)

A 6×30 straight-through finderscope

The two Plossl eyepieces included with the SkyLine 6 are really all you need starting out – the 25mm is great for low-power viewing of deep-sky objects, and the 9mm provides enough magnification for viewing the planets and smaller deep-sky objects like globular clusters – though a 6mm “redline” would be a good aftermarket addition, providing 200x magnification. Both eyepieces are well-made with multi-coatings and blackened lens edges, though the 9mm is a bit short on eye relief and requires you to jam your eye into it to take in the entire field of view. 

The included 6×30 finder provides an upside-down image with crosshairs and a field of about 7 degrees, similar to a pair of 7×50 binoculars. However, the image is rather dim and with only 30mm of aperture you can’t see much more than your naked eye can. A red dot finder or Telrad is easier to use, and a 9×50 shows more stars and deep-sky objects, but the 6×30 does the job.

What Can You See?

The SkyLine 6” can easily show you the phases of Mercury and Venus and the ice caps on Mars. When Mars is close to Earth during what’s termed opposition – for a period of about 6 months every 2 years –  you’ll be able to resolve a few dark markings on its surface at high magnification. The Moon shows thousands of craters and other surface details. 

The SkyLine 6” clearly resolves the moons of Jupiter into disks – albeit tiny – and they can easily be seen along with their shadows when they transit across Jupiter. Jupiter itself sports many colorful cloud belts and storms along with the famous Great Red Spot. Saturn’s rings are easy to see even at low magnification; high power reveals the Cassini Division and cloud belts on Saturn itself on a steady night, along with up to 8 moons circling Saturn. Uranus and Neptune appear as blue-teal dots; one or two of Uranus’ 4 large moons may just barely be visible while Triton is a little easier to spot orbiting Neptune – though these moons require dark skies to see clearly due to their faintness. Pluto is practically impossible to see with a 6” telescope as it is constantly getting further from the Sun and thus dimmer for the next century.

Viewing deep-sky objects with the SkyLine 6, or any telescope, is dependent on your light pollution levels, but even city skies will still allow you to see bright open and globular clusters along with of course double stars. Dark skies will enable the SkyLine 6 to reveal thousands of galaxies, including the dust lanes and hints of spiral arms in some of the brightest ones, as well as resolve globular star clusters into their individual stellar components. The large emission nebulae like the Orion Nebula, the Lagoon, and the Swan look wonderful, especially with an added UHC filter, and you can start to go after the smaller and colorful planetary nebulae like the Cat’s Eye or the Ring. 


Slightly More Expensive

No 2″ Focuser

The SkyLine 6 is slightly more expensive than other 6” f/8 Dobsonians, such as the XT6, but by the time you account for the SkyLine’s included eyepiece the gap is pretty much closed. The Apertura DT6 is exactly the same telescope as the SkyLine 6” apart from the lack of a 9mm eyepiece and often available at a lower price, but not always in stock. The only scope we might consider having better value is the Sky-Watcher Heritage 150P which has a wider field of view, collapsible tube, and considerably lower price, but it’s a tabletop telescope and also subject to stock issues at this time.

The lack of a 2” focuser on the SkyLine 6” is considered to be a drawback by some, but vignetting occurs with many of the mass-market 6” f/8 telescopes and 2” eyepieces even if they can technically accommodate them. 


The Orion SkyLine 6” is a great scope, and one that we certainly recommend, though we’d recommend seeing if the Apertura DT6 is in stock at a lower price before purchasing. An 8” or 10” scope from Orion, Apertura, or another manufacturer may also be worth considering, as one will have basically the same size tube and mount but provide much better views due to the greater light gathering ability and resolving power that more aperture brings.