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Apertura AD12 Dobsonian Review: Editor’s Choice

The Apertura AD12 is a big scope that’s ideal for a big person with a big house and/or a big vehicle, but it provides big, bold, bright, and beautiful views of the night sky.

Included in the Ultimate Telescope Shortlist

The Apertura AD12, also sold as the Zhumell Z12 and Orion SkyLine 12, is the largest of the GSO/Apertura Dobsonian line. It’s more or less a scaled up version of the AD8 and AD10, and the accessories and features provided are basically identical – the only difference is the aperture. As such many of our comments about it also apply to those telescopes as well. If the Apertura Dobsonians are not available in your region, the Orion SkyLine, Zhumell Z, GSO Deluxe, and Omegon Advanced Dobsonians are all pretty much the same both in design and accessories.

There are a few reasons, besides cost, that we generally stop at 12” for our recommendations for beginner telescopes or indeed telescopes in general. For one, anything over 12” is going to tend to be a truss tube, and while commercially mass-manufactured instruments exist, a large Dobsonian really should be a custom-made truss using lightweight materials and not particle board. The AD12 is a pretty great demonstration of this – its tube is too long to fit across the back of a vehicle horizontally, and you really should be in good health and/or have a way to simply roll the telescope outside if you plan on using it frequently and without help.

How It Stacks Up
Rank 1
Apertura AD12
4.8

Included in the Ultimate Telescope Shortlist

What We Like

  • Great optics
  • Huge aperture
  • Easy to use
  • Quality accessories


What We Don't Like

  • Bulky
  • Heavy
  • Needs time to cool down
  • Poor quality laser collimator


Bottom Line
TelescopicWatch Editor's Choice

The Apertura AD12’s colossal aperture will show you things that smaller beginner telescopes simply can’t, and will stave off your thirst for an even more expensive and monstrous instrument for a while. However, it’s best accompanied by a smaller instrument if possible and there are certain lifestyle choices required to make it a practical telescope for you.

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For purchasing this telescope, we highly recommend HighPointScientific, the largest telescope retailer in the United States. Their knowledge of the subject, combined with features like a price match promise, free lifetime tech support, a 30-day return policy, and financing choices, makes them a great pick.

The Optical Tube

The AD12 is a 12” f/4.9 Newtonian reflector on a Dobsonian mount, the same as all of the other Apertura Dobsonians. With its 1.5-meter (58”) long tube, minivans, SUVs, and even small pickup trucks can’t accommodate the tube sitting sideways across the back. Thus, most vehicles will require you to put a seat down for the tube alone, which is at the very least a moderate inconvenience. The tube also weighs 48 pounds (about 22 kg), which is not easy to lift, especially for a wide, slippery metal tube. Lifting straps or a dolly would be a good idea.

At f/4.9, there’s, of course, coma, which is visible at low magnifications like with the included 30mm SuperView eyepiece. A coma corrector will fix this, but be prepared to shell out big bucks for one. 

Unlike smaller Dobsonians, the AD12’s mirror is thin enough that it needs a serious floatation mirror cell. The primary mirror sits on 3 triangles, each with 3 points, to distribute its weight so it does not sag under its own weight. Collimating it is the same, however, with 3 spring-loaded knobs and the ubiquitous 3 useless locking bolts, which should probably be removed from the telescope before they crack the primary mirror or otherwise cause problems. There’s also a battery-powered cooling fan, which helps significantly reduce the time needed for the primary mirror to cool down. The AD12’s primary mirror is BK7 glass, which takes a fair amount of time to acclimate to the ambient temperature if brought outdoors from a warm indoor setting or left in a hot vehicle all day. This is alleviated by the fan, but expect to still spend a fair amount of time waiting to get sharp views. This doesn’t mean you can’t use the telescope right away; you can. Just keep in mind that you may not want to point 400x at Uranus to look for its moons immediately after bringing the telescope outside. 

The 2″ Crayford focuser that comes with the AD12 is the same as the GSO-branded and made dual-speed Crayford that comes with their Ritchey-Chretien, Cassegrain, imaging Newtonian, and, of course, Dobsonian telescopes, as well as some third-party rebrands. A Crayford focuser works by rolling the focuser draw tube against a set of 4 rollers and a piece of Teflon (PTFE) plastic, with no gears, teeth, or other things in the 10:1 reduction knob. This 10:1 reduction knob makes it possible to focus very precisely. This is especially helpful when using the AD12 at very high magnifications. 

Apertura AD12 Accessories

The Apertura AD12 comes with two eyepieces: a 2”, 30mm focal length “SuperView” (50x) and a 1.25” 9mm Plossl ocular (167). There’s also a 9x50mm right angle correct-image finder scope, a laser collimator, and a very low quality 1.25” “Moon filter” included.

The 9×50 finder does what it’s supposed to do: you can see much fainter stars than with your naked eye by a few magnitudes, along with bright deep-sky objects even when light pollution washes them out to the naked eye, but it’s not the best for beginners. You can’t see the crosshairs very well in the dark, and using it requires dead-reckoning by sighting down the tube and then looking through the finder. It’s easy to get lost or overshoot your target. A zero-power reflex sight or red dot finder is a better choice for a beginner and also complements the 9×50 nicely. 

The laser collimator that comes with the AD12 is said to be part of its “value,” but in reality, it is a poorly made generic item that can be bought on Amazon for less than $30. Due to its substandard design and total lack of quality control, not only is it not all that intuitive in the first place, but the majority of these lasers ship with a beam that’s not concentric with the barrel. Unless you enjoy taking the time to turn some tiny hex screws with the whole laser in a V-block, it will simply give you a completely inaccurate perception of how well your telescope is collimated and might hurt your collimation more than help it. A collimation cap can be made or purchased for very little money, and a quality Cheshire or laser isn’t too expensive. And in a pinch, you can collimate with just your eyepieces and a star. Check out our collimation guide for more information. 

The included 30mm SuperView, which provides 42x with the Z10, is a pretty good low-power eyepiece. You might notice that stars toward the edge are less-than-sharp and look like seagulls or crosses; this is partly an issue with how the SuperView design (basically a modified Erfle, a design invented in the 1930s) works in a fast telescope, and partly the coma inherent in a fast instrument with any eyepiece or accessory. However, it’s definitely an improvement compared to the typical 25mm Plossl or Kellner, which many beginner telescopes include, and which tend to be pretty mediocre in an f/5 telescope, in addition to providing a rather cramped field of view for low-power sweeping.

The 9mm Plossl that comes with the Z10, which has a magnification of 139x, has very little eye relief. You have to practically cram your eye into it to see the full apparent field of view, which is only a little less than 50 degrees. Thankfully, it’s quite sharp, and 139x will show you quite a lot of detail on the Moon and planets, as well as being a good general medium-high power for small deep-sky objects and double stars, though it’s hardly pushing the limits of the telescope, especially on a good night of steady seeing.

The included 1.25” “Moon filter” is not only almost completely unnecessary and, of course, not usable with the low-power eyepiece, which it would theoretically be best with, but it’s extremely low in quality, tinting the view green and adding a bit of fuzziness to boot. You’re best off discarding it.

AD12’s Dobsonian Mount

The AD12’s mount is the same as the other Apertura AD Dobsonians. It’s made almost entirely out of particle board, and swivels on plastic roller bearings, much like a “lazy Susan”. Unfortunately, this system doesn’t scale up too well with the weight and size of the AD12—thankfully, you can buy aftermarket Teflon pads for a fairly reasonable price to convert it to pivot like a standard Dobsonian. 

For altitude (up/down) motion, the AD12 uses ball bearings, which can be adjusted along the tube with a hex wrench to put the bearings at the precise center of balance of the telescope, depending on what eyepieces, finder, and other accessories you are using. You can also tighten the bearings simply by turning the knobs on them to keep the scope locked in place or set an optimal amount of friction for smooth motion. The bearings are, however, attached to the AD12’s tube, and lining them up well enough with the notches in the base is hard to do, and can be a little scary to do unassisted. We strongly advise practicing assembly of the AD12 indoors under well-lit conditions before bringing it to a star party.

The AD12’s base is heavy at 38 lbs (17 kg). It feels even heavier than the tube due to its awkward size and the density of the particle board. We would definitely recommend putting it on wheels if you can, or replacing it with a lighter weight plywood aftermarket or homemade base.

Should I buy a Used Apertura AD12?

A used AD12 is a great scope. Beware of the condition of the mirror coatings; recoating is possible but can get expensive. A damaged base can be easily replaced if you have any woodworking skills, or you can order one from High Point or a third-party vendor. Any dents in the tube can either be repaired or simply ignored, as they’re unlikely to intrude on the optical path of the telescope.

Alternative Recommendations

The Apertura AD12 is our top recommendation in its price range (unless you have some issues with transporting or storing a massive 12” solid-tubed Dobsonian). Here are some smaller-aperture and more portable alternatives that we recommend in lieu of the AD12.

Under $1000

  • The Apertura AD10/Zhumell Z10/Orion SkyLine 10 is essentially a shrunken AD12, with a shorter optical tube and more compact base that are more likely to fit in a vehicle. However, you are of course surrendering some performance here due to the smaller aperture.
  • The Apertura AD8/Zhumell Z8/Orion SkyLine 8 is essentially the same in size and form factor to the 10” model, and if budget isn’t a concern we’d recommend you stick with the AD10/Z10 instead. However, if weight is a factor and you must have a solid-tubed instrument, the 8” is just fine to start with – though you’ll probably find yourself eyeing an AD12 as an upgrade later.
  • The Explore Scientific 10” Hybrid Dobsonian is of course a step down in performance compared to the AD12, but comes in a radically compact form factor compared to it or any of the 8” or 10” solid-tubed scopes we recommend. However, you’ll need to budget for some new eyepieces, a better finder scope, and a shroud, and the 10” Hybrid’s single-speed 2” Crayford focuser may not satisfy you if you like observing at high magnification often. Assembly is also a bit more complicated, as is collimating from the front of the scope using an included hex wrench.

$1000-$2000

  • The Explore Scientific 12” Truss Tube Dobsonian offers similar if not outright identical performance to the AD12, and the included 2” dual-speed Crayford focuser is great too. However, as is unfortunately the case with most Explore Scientific offerings, the included finder and eyepiece are low-quality, and you’ll need a shroud – as well as perhaps some DIY baffling upgrades – to keep stray light out of this scope. Prepare to spend a couple hundred dollars on upgrades and accessories right out of the gate if you want to be satisfied with this instrument.
  • The Celestron StarSense Explorer 10” Dobsonian is a bit lighter and more portable than some other 10” solid-tubed Dobsonian offerings (and quite a bit easier to handle than the AD12) thanks to its weight-optimized trimmed base and the carry handles attached to the optical tube. You also of course get the award-winning Celestron StarSense Explorer technology to assist you in finding your way around the night sky and getting aimed at faint deep-sky objects. However, the price is a bit steep, especially considering the lack of other features or accessories – the focuser is a mere single-speed 2” Crayford unit, and only a single 25mm Plossl eyepiece and red dot finder are included. An 8” model is available for less money, but given the identical form factor and the superiority of the 10” in almost every way, we would recommend you go for the 10” unless price is a huge concern.
  • The Explore Scientific 10” Truss Tube Dobsonian is similar to the 12” model in many ways – the collapsed form factor is extremely compact, there is no cheap particle board or plastic to be found, and the included accessories are garbage. The price is a bit lower and the scope is a bit easier to handle, however – though you’re of course sacrificing some performance stepping down from a 12” to 10”, especially when it comes to views of faint deep-sky objects where the 44% light gathering improvement of a 12” vs. 10” really shows up.

Aftermarket Accessory Recommendations

The AD12 is a rather expensive scope, so don’t be afraid to skimp on accessories for it. A zero power reflex sight Telrad, Rigel Quikfinder, or Quinsight, for starters, will greatly assist in aiming the AD12-you can use the reflex sight by itself to aim at bright targets, or use it to get in a general area where you think your target is and home in with the 9×50 RACI. 

For higher magnification eyepieces you could get a 6mm gold-line (250x) and/or a 4.5mm Astromania (333x with the AD12), but the AD12 works best with fancier eyepieces. We particularly like the Baader Hyperion and Explore Scientific 82-degree series, both of which come in a variety of focal lengths for low, medium, and high magnifications. We’d recommend something in the 5-7mm range, something in the 11-14mm range, and something in the 16-25mm range at the minimum for a good range of magnifications that can be used on a wide variety of targets.

You might also want a coma corrector such as the Explore Scientific HRCC or Tele-Vue Paracorr II – yes, they’re pricey, but you’ll be rewarded with truly sharp stars all the way to the edge of the field of view.

A nebula filter like the Orion UltraBlock 2” UHC will enable you to see emission nebulae more easily under light-polluted skies and will help boost contrast even under dark skies, but is not a replacement for them and does not work on non-nebula targets like star clusters and galaxies. It’ll work with both 1.25” and 2” eyepieces thanks to the threaded 2” to 1.25” adapter provided with the AD12.

What can you see with Apertura AD12?

With the AD12, you can see many deep-sky objects that people with smaller scopes can only dream about. 

Within the solar system, atmospheric turbulence—what is termed “seeing”—is the primary limitation when it comes to what you can see with the AD12. You can easily see the phases of Venus and Mercury, and the Moon will show amazing detail on almost any night. Mars will show some dark spots, its ice caps, and any dust storms when it’s close to Earth, with the best apparitions occurring once every couple of years. Careful observing techniques may even manage to reveal its tiny asteroid moons, Phobos and Deimos, though they are quite tough to spot.

Jupiter’s cloud belts look magnificent with the AD12 on a steady night, and you’ll be able to easily see the Great Red Spot. The giant planet’s moons are tiny disks that can transit the planet with their shadows following behind, and on a perfect night you can just barely spot a brown spot on Ganymede known as Galileo Regio, named for the astronomer who discovered the moons.

The AD12 will show you a surprising amount of detail on and around the outer gas giants, too. Saturn’s rings are visible, as is the Cassini Division within them, and on a really good night, so is the Encke gap. You can also see quite a few cloud bands on Saturn itself and a blue-gray polar region where the planet’s hexagonal polar storms lurk. A half dozen or so of Saturn’s moons are visible, with Titan visibly larger than a point source and sporting a gold-yellow hue.

Uranus and Neptune are no longer mere fuzzy stars in the AD12, but worlds in their own right with visible moons. Uranus’ greenish disk may sport very slight cloud markings, and its 4 brightest moons, Ariel, Umbriel, Oberon, and Titania, are faintly visible. Neptune is around half the angular size of Uranus and much fainter, but it is clearly a bluish disk, and its largest moon, Triton, can be seen more easily than the moons of Uranus, thanks to its larger size and more reflective surface. 

Pluto is also visible as a star-like point with the AD12, though it’s currently stuck in a crowded neighborhood of stars in Sagittarius for the foreseeable future and will be hard to identify individually. Ceres, the closest dwarf planet, and Vesta, the second-largest asteroid, are easier to catch with the AD12. They are both easily seen in the 9×50 RACI and look like tiny, non-stellar gold dots. On the best nights, Vesta has a very slight oblong shape.

Outside the Solar System, the AD12 can show a lot, but the best views require a clear and dark night sky away from city lights, which is why we stress that you make sure you can easily and safely transport this mammoth telescope. If you can’t see the Milky Way when you look up, the AD12 will certainly disappoint on galaxies, and the views of most other deep-sky objects will be greatly diminished by light pollution.

The AD12 will have no problem resolving even the tougher globular clusters. Thanks to its large aperture, the AD12 can also show you the spiral arms and dust lanes of dozens of the brightest galaxies—and reveal thousands upon thousands more, assuming you have good skies. M51’s spiral arms are clearly visible, as are the H-II regions that dot the spiral arms of M33. The Andromeda Galaxy, M31, takes up several fields of view. You can see an open cluster called NGC 206 inside it, as well as a small globular cluster called G1 a few degrees away (though you can’t see it without a much bigger telescope). 

You’ll also be able to spot thousands of open star clusters with the AD12, many of which have colorful stars, dust lanes, or are embedded in larger nebulae or clusters themselves. They look magnificent, even from the city skies. They range from compact, almost globular-like clusters like M11 and M35 to looser clumps like the Pleiades (which also has a faint reflection nebula surrounding it that can be seen with the AD12 under dark skies).

The AD12 also reveals dozens of planetary nebulae, many of which have interesting color and intricate details. These are so bright that they’ll look great even under suburban and city skies. Planetary nebulae range from the huge, bluish Dumbbell and Ring to the tiny, emerald-green Cat’s Eye. Some, like the Blinking Planetary Nebula, have white dwarfs in the middle that are easy to see, while others do not. 

Emission nebulae like Orion and the Lagoon look stunning with the AD12, especially with dark skies and a UHC filter, and on a perfect night, you can just barely glimpse the famous Pillars of Creation within the Eagle Nebula, M16. 

Transporting & Setting Up The AD12 – Important Notes

The AD12’s optical tube is large (at 14” across and 58” long) and heavy (at about 48 pounds), so some consideration must be taken in moving it. Unlike with 8” and 10” instruments, the AD12’s tube will not fit across the back seat of most cars; you’ll need to fold down a seat unless you have a truck or van. Picking it up can also be problematic, as the painted metal tube is slippery and there are few points to grab. Setting the scope in the base is also hard because you can’t grab the bearings without hurting your fingers when putting the scope together, and they have to be moved very carefully into their slots. Obtaining lifting straps or moving the scope on a cart or dolly is a good idea if you have to move it frequently by yourself.

The particle board rocker box/base of the AD12 weigh in at 38 pounds. This doesn’t sound that bad, but you have to spread your arms out and carry it at an awkward angle, and it’s quite dense. Carrying it a long distance may cause you to tire or injure yourself. Making or buying a replacement plywood base, or simply putting the scope on wheels, might be a good idea.

Performance Score Of Apertura AD12

4.8

Quantitative measurements of how the telescope performs in various performance categories:

Optics

5/5

Focuser

5/5

Mount

5/5

Planetary

4/5

Rich Field

5/5

Accessories

5/5

Usability

5/5

Portability

2/5

Value

5/5

Aperture:305mm
Optical Design:Newtonian Reflector
Mount Design:Manual Alt-Azimuth
Focal Length:1520mm
Focal Ratio:f/5
Focuser:2" Dual Speed Crayford
Total Assembled Weight86.1 lbs
Warranty:2 year

An amateur astronomer and telescope maker from Connecticut who has been featured on TIME Magazine, National Geographic, Sky & Telescope, La Vanguardia, and The Guardian.

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