Orion Skyline 6 Review Hands-On

Introduction

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.

Optical Design

The Orion SkyLine 6 is a 6” (152mm) f/7.9 Newtonian reflector with a focal length of 1200mm. This optical configuration is widely regarded as one of the most forgiving and reliable designs for a telescope of this size.

Primary Mirror Quality

A 6” f/8 primary mirror is very easy to manufacture, deviating from a spherical surface only slightly as a parabola. Because of this, manufacturers are able to produce these mirrors very accurately, and they tend to suffer from very few quality issues.

As a result, the mirrors in telescopes like the SkyLine 6 are typically smooth, well-figured, and capable of delivering razor-sharp views with minimal effort.

Collimation & Ease of Use

Achieving sharp images is made easier by the SkyLine 6’s well-designed collimation system. The primary mirror can be adjusted without any tools, making routine collimation quick and beginner-friendly.

The secondary mirror does require a hex key for adjustment by default, and this is generally best left as-is unless fine tuning is absolutely necessary.

Crayford Focuser

Although limited to 1.25” eyepieces, the Crayford focuser on the SkyLine 6” is high-quality and far superior to the plastic rack-and-pinion or helical focusers commonly found on beginner 6” and smaller telescopes.

A 2” focuser would add unnecessary weight to the front of the telescope and require a larger secondary mirror, offering little practical benefit for this instrument.

The Crayford design uses no gears or lubricants and features multiple tension adjustments. An internal hex screw sets the baseline friction (useful if you regularly use heavier eyepieces), while two small thumb screws allow fine tension adjustment or complete locking of the focuser.

Mount

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 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 6x30 finder provides an upside-down image with crosshairs and a field of about 7 degrees, similar to a pair of 7x50 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 9x50 shows more stars and deep-sky objects, but the 6x30 does the job.

What can you see?

The Moon & Inner Planets

The SkyLine 6” can easily show the phases of Mercury and Venus, as well as the polar ice caps on Mars. When Mars is close to Earth during opposition — a period lasting roughly six months every two years — you’ll be able to resolve a few dark surface markings at high magnification.

The Moon is a standout target, revealing thousands of craters, rilles, and other surface features with excellent contrast.

Jupiter, Saturn & the Outer Planets

Jupiter’s four Galilean moons are clearly resolved into tiny disks, and their shadows can easily be seen transiting across the planet’s cloud tops. Jupiter itself displays multiple colorful cloud belts, storms, and the famous Great Red Spot.

Saturn’s rings are obvious even at low magnification. Under steady seeing conditions, higher power reveals the Cassini Division, subtle cloud bands on the planet, and up to eight moons orbiting Saturn.

Uranus and Neptune appear as small blue-teal disks. One or two of Uranus’ four largest moons may be barely detectable, while Triton is somewhat easier to spot orbiting Neptune — though dark skies are required due to their faintness.

Pluto is essentially impossible to observe with a 6” telescope, as it is extremely faint and continues to recede from the Sun.

Deep-Sky Objects

As with any telescope, deep-sky performance depends heavily on light pollution. Even from city skies, the SkyLine 6” can show bright open clusters, globular clusters, and numerous double stars.

Under dark skies, the SkyLine 6 can reveal thousands of galaxies, including dust lanes and hints of spiral structure in the brightest ones. Many globular clusters can be resolved into individual stars.

Large emission nebulae such as the Orion Nebula, Lagoon Nebula, and Swan Nebula look spectacular, especially when using a UHC filter. Smaller and more colorful planetary nebulae like the Ring Nebula and Cat’s Eye Nebula are also well within reach.

Drawbacks

The SkyLine 6 is slightly more expensive than other 6” f/8 Dobsonians, such as the XT6. However, once the included eyepiece is taken into account, the price difference largely disappears.

The Apertura DT6 is essentially the same telescope as the SkyLine 6” but lacks the included 9mm eyepiece and is often available at a lower price — though availability can be inconsistent.

The only telescope that may offer better overall value is the Sky-Watcher Heritage 150P, which features a wider field of view, a collapsible tube, and a significantly lower price. That said, it is a tabletop telescope and also frequently subject to stock shortages.

1.25” Focuser Limitation

Some users consider the lack of a 2” focuser to be a drawback. In practice, many mass-market 6” f/8 Dobsonians suffer from vignetting when using 2” eyepieces anyway, even if they can technically accept them.

Conclusion

The Orion SkyLine 6” is an excellent telescope and one we confidently recommend. Before purchasing, it’s worth checking whether the Apertura DT6 is available at a lower price.

Prospective buyers may also want to consider stepping up to an 8” or 10” telescope from Orion, Apertura, or similar manufacturers. These models use a very similar mount and tube size while offering significantly improved light-gathering ability and resolving power.