Orion StarBlast 6 Tabletop Telescope Reviewed: Recommended Scope

The Implications of Low Focal Ratio of f/5

The Orion StarBlast 6 is a 6” (150mm) f/5 Newtonian reflector with a 750mm focal length. I found this similar optically to the 150mm f/5 tabletop scopes from Sky-Watcher, Bresser, and a variety of other 150mm f/5 Newtonian reflectors.

Unlike regular 6” Dobsonians, which have a focal ratio of f/8 and a focal length of around 1200mm, the StarBlast 6 is a stubby f/5 with a focal length of 750mm. Consequently, compared to the free-standing 6″ Orion XT6 Dobsonian, the StarBlast 6 produces 37.5% lower magnification and a 60% wider field of view, regardless of the eyepiece type or focal length. I derived these percentages from their respective formulas. Additionally, the tube is much shorter in StarBlast 6.

However, at a low focal ratio of f/5, three more issues could happen:

1. You’re beginning to run into coma, an optical aberration distinctly recognized when stars appear with comet-like tails near the edges of the field of view.
2. Cheap eyepieces will struggle to produce sharp images across the entire field of view, which is one reason why you can see me using a costlier Explore Scientific 82° eyepiece with the StarBlast 6 in the below image.
3. At a low focal ratio, I always find collimation to be a bit more of a pain. All Newtonian reflector telescopes require minor adjustments from time to time to ensure that the mirrors are properly aligned to provide the best view, which is called collimation. The collimation process is not hard to do and with a little practice, it only takes a few minutes. Orion includes a collimation cap for this task.

The Upgraded Focuser

The focuser on the Orion StarBlast 6 was finally upgraded to a 2” rack-and-pinion unit in 2023 from the previous 1.25″ version. This focuser is definitely not as smooth as a Crayford design but I’d say that it works well enough.

The increase in the eyepiece barrel diameter from 1.25″ to 2″ allows the usage of 2” wide-angle eyepieces that have an absolutely huge field of view. But the said eyepieces can add up to a significant proportion of the cost of the StarBlast 6 itself, as well as looking a little silly on such a small scope.

There is also a removable extension tube that allows for enough focus travel that a coma corrector will work in this telescope if you wish.

The Mediocre Eyepieces

The Orion StarBlast 6 includes two Plossl eyepieces, each with a 52-degree apparent field of view: a 25mm for 30x and a 10mm for 75x.

I find these eyepieces to be a little lower in quality than the old Sirius Plossls Orion used to sell in the pre-2023 StarBlast 6 models. While the newly introduced eyepieces are functional, they have some glare/internal reflections and certainly aren’t the sharpest. However, I think they will suffice.

I also need to warn you that the 10mm is very short on eye relief, which is typical of the Plossl eyepiece design. Short eye relief means it requires you to jam your eye into the lens to take in the full field, which is rather uncomfortable.

Of the two, this 10 mm with 75x magnification is your high-power eyepiece. However, a scope of this aperture is capable of much higher power. In the future, I would recommend you plan for eyepieces for at least 160X and perhaps higher. Above that level, the atmosphere will start to become the limiting factor so I can’t tell you exactly what the maximum useful magnification will be for your location and situation.

A 150 mm aperture telescope would normally be rated up to 300X, but atmospheric conditions will vary from night to night and may limit you below that. Build your eyepiece set over time as you learn what your local situation will allow.

Other Accessories

You also get a red dot finder to aim the Orion StarBlast 6, which works but has a rather small window and difficult-to-use adjustments. I believe replacing it will significantly improve your viewing experience.

Lastly, a basic smartphone adapter to take photos of the Moon through the eyepiece is supplied with the StarBlast 6, along with a basic Moon map and a star chart showing the locations of 600 deep-sky objects that can be seen with the telescope.

Mount

The base or mount is a “tabletop” Dobsonian-style altitude/azimuth or AltAz mount, the same as its smaller cousins. AltAz means the optical tube pivots up and down while the base rotates left and right in a Lazy Suzan turntable style. Sticklers will note that it’s technically a single-arm fork design, with the scope pivoting up and down on a single bolt and Nylon/felt bushing while it moves in azimuth (left-right) on Teflon pads as in a Dobsonian.

The design makes the StarBlast 6 very easy and intuitive to use.

It also includes a tension adjustment knob, which allows you to set the right friction so that the optical tube does not move on its own. If you purchase additional eyepieces, a Barlow lens, or other accessories that go in the focuser, you will likely make adjustments to this knob during the night to compensate for the changing weight and balance.

The StarBlast 6 optical tube attaches to the mount with a pair of tube rings. The advantage of the tube ring mounting method is that I can rotate the optical tube within the tube rings to get the eyepiece into the most comfortable position. They shouldn’t be clamped super tight, as you want to be able to rotate that tube or slide it forward or back to gain the best balance and eyepiece position.

The large footprint of the mount and the weight of the whole package may lead to some difficulty in finding a suitable surface to set the scope on, which I’d argue is the mount’s biggest drawback. Some people love the tabletop design and some do not. This is purely a matter of personal preference.

The new 2023 version of the StarBlast 6 lacks the ability to be upgraded to an Intelliscope like its predecessors and is a manual-only instrument. Intelliscope is a PushTo-style computer assist that allows you to find things in the sky with the assistance of a computer that tells you where to point the telescope.

Should I buy a Used Orion StarBlast 6?

A used Orion StarBlast 6 tabletop is likely to be an older, pre-2023 unit with an all-plastic 1.25” focuser. These scopes are good but do not permit as wide a field of view since they cannot use 2” eyepieces without substantial DIY modifications. However, they can be upgraded to use the Orion IntelliScope digital setting circles or may already come supplied with one as the “StarBlast 6i.” None of these products are available new or as upgrades to the current version of the StarBlast 6.

As usual, when buying a used Dobsonian, make sure that the telescope’s optics are free of corrosion, as recoating the primary or secondary mirror is likely to impinge upon any cost savings at this size.

Likewise, the tabletop base should be in good shape and free of apparent damage that may compromise its motions.

Alternative Recommendations

It should be noted that the new Orion StarBlast 6 is also identical to the Bresser Messier 6” f/5 tabletop Dobsonian which is a perfectly good substitute. We also have a few other alternatives that you may wish to consider:

Under $350

• The Sky-Watcher Heritage 150P shares the optics and basic design of the StarBlast 6, but features a collapsible tube for increased portability and a 1.25”-only helical focuser. It’s also significantly cheaper and includes better accessories.
• The Sky-Watcher Heritage 130P offers the same features and accessories as the larger 150P model but with slightly less aperture and a lower price, delivering slightly dimmer views but still offering plenty of capability.
• The Orion StarBlast 4.5 Astro is essentially a shrunken StarBlast 6, with a significantly smaller 114mm primary mirror and a 1.25”-only focuser but a huge field of view nonetheless thanks to its short 450mm focal length.

$350-$550

• The Sky-Watcher Virtuoso GTi 150P offers fully motorized tracking and GoTo, with identical views to the StarBlast 6 and a collapsible tube shared with the Heritage 150P. It also comes with a pair of decent eyepieces to get you started and can be aimed manually, with the GoTo system being operated by your smartphone/tablet. A 130mm version based on the Heritage 130P is also available.
• The Apertura AD6 has a way better dual-speed Crayford focuser and will provide similar brightness and resolving power to the StarBlast 6. Its longer f/ratio of f/8 means easier collimation and no coma—at the expense of a much narrower maximum field of view and a much bulkier tube assembly. This scope stands on the ground without any need for a table or tripod.
• The Celestron Astro Fi 130 is a fully computerized GoTo 130mm f/5 reflector with a 2” focuser equipped to allow for a huge field of view and only slightly less capability than the StarBlast 6. It cannot be aimed manually at all but is easily operated wirelessly via your smartphone/tablet and comes equipped with a fairly sturdy tripod.

$550-$800

• The Apertura AD8/Zhumell Z8/Orion SkyLine 8 offers nearly twice as much light gathering area and significantly more resolving power than the StarBlast 6, along with numerous features and accessories such as a high-quality dual-speed Crayford focuser, a built-in fan, a right-angle finder scope, and two decent included eyepieces. It stands on the ground and is easy to aim thanks to its smooth Dobsonian base. The AD10/Z10 is also an excellent pick if you can afford it.

Aftermarket Accessory Recommendations

The StarBlast 6 would greatly benefit from additional eyepieces.

You can achieve nearly the maximum field of view the StarBlast 6 has to offer using a 2″ wide-angle ocular like the Apertura 32mm SWA (23x): 3 degrees, or 6 times the angular diameter of the Moon (wider-field eyepieces are limited by exit pupil size and coma without significant expense).

A 15mm redline eyepiece (50x) is ideal for medium power, while a 6mm “goldline” or “redline” provides 125x, which is ideal for lunar and planetary viewing on most nights. On a night of good seeing, a 3.2mm Agena Starguider (234x) is ideal for planetary observing or splitting double stars with the StarBlast 6, reaching nearly the maximum the telescope can handle (about 300x).

You may also enjoy a 9mm redline (83x) to replace the stock 10mm Plossl eyepiece.

A better red dot finder will significantly improve your experience using the StarBlast 6 and I would highly recommend purchasing one to replace the stock unit.

And of course, a good UHC nebula filter like the Orion UltraBlock 2” (able to work with 1.25” eyepieces by threading onto the StarBlast’s provided adapter) will significantly improve the contrast of nebulae against the background sky at the eyepiece, as well as bring out previously-unseen objects under dark skies.

What Could I See?

The StarBlast 6 offers impressive views of open star clusters such as the Double Cluster, M11, M35, and the Pleiades (M45). Even under light-polluted skies, these stunning clusters were still visible due to the scope’s ample 150mm aperture.

Globular clusters such as M3, M13, M15, and M22 were easily resolved at high power with the StarBlast 6, though I found that a better eyepiece than the 10mm Plossl with a slightly shorter focal length for 100x magnification or more is optimal to resolve individual stars in these clusters.

The bright emission nebulae like Orion (M42) and the Lagoon (M8) looked superb even under light-polluted skies, though dark skies and/or a UHC nebula filter provided me with the best views. With a 2” wide-angle eyepiece and UHC filter under decent conditions, the StarBlast 6 provides you with fantastic views of the Veil Nebula supernova remnant and the huge North America Nebula in Cygnus.

Galaxies require dark skies to appear as anything more than dim fuzzy smudges in the eyepiece, but under good conditions, the StarBlast 6 revealed hundreds of galaxies, including the Virgo Cluster. Many of the brighter galaxies, such as M31, M82, and M64, show details such as dust lanes to the discerning observer.

Planetary nebulae like the Blue Snowball also begin to show fine detail and a wide array of colorful tones, and there are countless double stars that you can split under good conditions with the StarBlast 6.

The StarBlast 6 does just as well as a “slower” f/ratio scope on the Moon and planets, though a very short focal length eyepiece or Barlow lens is necessary for high magnifications.

You can see the phases of Mercury and Venus, polar ice caps and dark markings on Mars when the planet’s proximity and our own planet’s atmospheric conditions permit, and the moons of Jupiter.

At high magnifications, Jupiter’s moons appear as tiny disks instead of points, which is particularly obvious when they transit in front of the planet and cast shadows. Jupiter itself displays a wide variety of shades and hues in its atmospheric cloud bands, with the prominent equatorial cloud belts and Great Red Spot usually appearing fairly obvious against the cream-colored equatorial regions.

Saturn’s rings look splendid, with the Cassini Division visible as a razor-thin gap and the planet showing a number of dull cloud bands, alongside a handful of moons.

Uranus is a teal disk, with moons too faint to see in a 6” telescope, while Neptune is a fuzzy blue dot and its moon Triton is fairly apparent under good conditions beside it.

Pluto will require a larger telescope than the StarBlast 6, preferably with a 10” or greater aperture, to see.