The Optical Tube
The BK7, or soda-lime plate glass, used in the Z10 is similar to what is found in many mass-produced telescopes. You’ll need to let the telescope sit if there’s an extreme difference between the outside temperature and where you’ve stored it, and that’s where the included battery-powered fan comes in. The fan significantly accelerates cooldown time, though it doesn’t eliminate it. But make sure to turn it off before you actually start observing so that the vibrations don’t disturb the telescope!
The Z10 is easy to collimate. The secondary rarely needs to be adjusted, but it does require tools. The primary, on the other hand, is just a simple mirror cell with a spring. However, you may want to remove the included “locking bolts” because they aren’t necessary and may even crack the mirror should the telescope take a fall. Some users have re-used the threaded holes where the lock bolts go to mount rubber feet so the telescope tube can be easily stood up on its end during setup or for storage purposes.
It’s a small detail, but the included plastic front cap for the Z10 can get stuck sometimes and is difficult to remove. A drill or hole punch and a $2 drawer pull knob from the hardware store will fix this problem.
The Z10 comes with the same GSO 2″ dual-speed Crayford focuser that comes with a number of Dobsonians, imaging Newtonians, Cassegrains, and Ritchey-Chretien instruments. It works by rolling the focuser draw tube against a set of 4 rollers and a piece of Teflon (PTFE) plastic, with no gears or teeth beside those in the 10:1 reduction knob, which you use for fine focusing. The focuser has a compression ring to grab your eyepieces without scratching them, and it includes a 1.25” adapter with filter threads and a compression ring as well.
The optical tube of the Z10 fits across the back of most vehicles and is actually shorter than that of some 8” Dobsonians. Contrary to popular belief, there is no need to purchase a case or a carry bag. If you’re concerned about marring the tube, just wrap it in a blanket or towel. Overall, the tube weighs 33 pounds (15 kg) so most people shouldn’t have too much trouble moving it, though its size and smooth metal surface can make it somewhat awkward. Some people buy or make lifting straps or add additional handles to make life easier.
The Zhumell Z10 includes a 9x50mm right-angle correct-image finder scope, a laser collimator, a cheap 1.25” “Moon filter”, and two eyepieces: a 2”, 30mm focal length “SuperView” (42x) and a 1.25” 9mm Plossl (139x).
The well-made 9×50 finder works fantastically as designed, and it will show many fainter stars than your naked eye can detect, along with many of the brightest deep-sky objects, even under rather light-polluted viewing conditions. However, using it can be difficult for beginners, and the crosshairs are somewhat difficult to see in the dark. Sighting along the tube and then looking through the finder to locate your target while also not massively overshooting it takes a bit of practice. A zero-power red dot finder or reflex sight such as the Telrad might be easier to use, but it is also well complemented by the 9×50, so there’s no reason to not just use both if you can afford the purchase.
The laser collimator included with the Z10 is advertised as being easier to use than a standard collimation cap or Cheshire and is also supposedly some of the “value” of the package. In fact, it’s a generic, cheap device that can be purchased separately for less than $30. Furthermore, the quality of this laser is quite low-the dimmer settings barely work, it’s not that accurate to begin with, and most of the time the laser itself is out of square with the body, which means it will never give you an accurate read on whether or not you’re collimated and will probably make things worse. Without hours of tweaking, it’s better left unused. A collimation cap can be made for practically nothing, and there’s always the star test—check out our collimation guide.
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 Z10’s included 9mm Plossl, which provides 139x, has rather little eye relief and requires practically jamming your eye into it to take in the full apparent field of view – which itself is rather narrow, at a bit 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 quality, tinting the view green and adding a bit of fuzziness to boot. You’re best off discarding it.
For azimuth, or side-to-side movement, the Zhumell/GSO Dobsonians use roller bearings, which are essentially a “lazy Susan” with more than a dozen tiny plastic rollers pushing between the ground board and the bottom of the rocker box. This is cheap, smooth, and it works well, but many users find it too loose and easily spun—particularly a problem when using it in windy conditions, with children, or for public events. Tightening the center bolt tends to lead to the opposite problem-the motions are too stiff. Thankfully, replacing the lazy Susan with PTFE (Teflon) pads like an ordinary Dobsonian uses can be done cheaply, and some companies even sell kits for it.
The Z10’s altitude bearings, which allow it to pivot up and down, are ball bearings with clutches to adjust their tightness/friction for optimal smoothness—and to lock them up should you be adding/removing a particularly heavy accessory. You can shift the bearings back and forth with a hex key along a track attached to the tube to adjust for the center of gravity with different accessories, though it’s best done ahead of time indoors as adjustment in the field is a huge pain.
As with all mass-manufactured Dobsonians, the Z10’s base, which is made out of particle board, comes packed flat and can be assembled with the included tools and screws in just a few minutes, no differently from the flat-pack furniture sold at a big box store. You’ll almost certainly wind up damaging the base over time, and it will be lucky to last more than 10 years before it breaks or succumbs to moisture damage, but by that point, you can go ahead and make a replacement out of plywood, which will be lighter, stronger, and more durable to boot.
Weighing 29 lbs (13 kg), the solid particle board base of the Z10 shouldn’t be that heavy, but it feels much worse to lug around despite the built-in handles thanks to its density and awkwardness. Replacing it with a homemade square plywood base reduces both of these problems, but you can also just throw the base or the whole scope on a hand truck or dolly to cart it around if the bulk intimidates you.
Should I buy a Used Zhumell Z10?
A used Z10 is a great scope, and there’s not a ton that can go wrong aside from wear to the mirror coatings or damage to the base. Both of these are fixable issues, however. Mirrors that look ugly probably just need cleaning, and if the coatings are truly damaged, they can be recoated for a few hundred dollars at worst, and a well-maintained coating may last a lifetime. A damaged or outright missing base is easier to remedy with just a jigsaw and some plywood, costing less than $50 and with a lighter weight to boot. Plus, if you spend time on it, you can make it look quite pretty.
A dented optical tube isn’t a big deal. Most dents on these scopes, which are kind of unavoidable if you use them often, don’t get in the way of the light, so you can ignore them.
The Z10 is easily one of the best telescopes available in its price range, or for beginners in general.
The Zhumell Z10 and identical Apertura AD10 are our top recommendations in its price range for good reasons. Taking everything into account, we suggest Apertura A10 over Zhumell Z10 9 times out of 10.
If you can’t get one due to availability or your geographic location, as we’ve mentioned previously, the Apertura AD10, Orion Skyline 10”, Omegon 10” ProDob, GSO 10” Deluxe, and Bintel 10” Dobsonian are all similar or identical to the Z10.These telescopes are all made by GSO and tend to have the same features with minor variations in the mounting and accessories. However, there are some benefits to be had with going smaller or spending more, so here are a few of our top alternative picks sorted by price.
- The Apertura AD8/Zhumell Z8/Orion SkyLine 8 is of course identical to the Z10 apart from the scaled-down aperture. You get the same high-quality features and accessories, as well as great value for the money. However, given that the tube length and the overall weight/bulk of the Dobsonian base is the same for both the 8” and 10” models, we would really recommend you just stick with the Z10/AD10 if budget is not a concern, as the 10” of aperture significantly outperforms an 8” and given the negligible difference in convenience the 10” is a significantly more capable telescope.
- The Explore Scientific 10” Hybrid Dobsonian is more compact than the Z10 thanks to its collapsible truss tube design, and features vastly superior bearings compared to the roller/ball bearings of the Z10, which make fine adjustment and balancing with heavier accessories easier. However, you get only a single-speed 2” Crayford focuser and basically no usable accessories, and a truss tube telescope like the 10” Hybrid needs a tight-fitting fabric shroud to keep stray light and moisture out of the open frame. By the time you upgrade all these, you’ll likely have spent nearly as much as the Z10 costs. As such, the main thing you’re paying for is the mechanical/portability aspects, and there’s going to be some inevitable confusion and deliberation from having to shop for so many extra items a la carte just to get started.
- The Sky-Watcher Virtuoso GTi 150P is significantly smaller and thus less capable than the Z10 thanks to its mere 6” of aperture, but it’s extremely compact thanks to its tabletop design and collapsible tube, provides a super-wide field of view, and features full motorized tracking and GoTo operated via your smartphone or tablet, as well as the ability to be aimed manually. You can also elect to purchase the manual Heritage 150P, which is identical apart from its lack of electronics, or 130mm f/5 versions of either (the Virtuoso GTi 130P and Heritage 130P respectively). Any will make a great beginner or “grab n’ go” telescope and arguably complements the Z10 extremely well too.
- The Apertura AD12/Zhumell Z12/Orion SkyLine 12 comes with the same features and accessories as the Z10, just scaled up a bit. However, a 12” solid-tubed Dobsonian’s optical tube assembly won’t fit horizontally across the back of most vehicles, the particle base is getting large and quite heavy, and carrying the tube yourself is awkward without adding lifting straps or a helper. You will probably end up wanting a hand truck to transport this telescope any significant distance, and bringing it in a car to dark skies – particularly if you’re trying to bring other people or camping gear with you – can be a bit of a pain. However, if you can handle the bulk, a 12” Dobsonian is even better than a 10” with 44% more light gathering ability and 20% more resolution, and blows away the views through smaller 6” and 8” telescopes which just feel like toys by comparison.
- The Celestron StarSense Explorer 10” Dobsonian is just as capable as the Z10, and has a lighter base and built-in carry handles for increased portability. You also get Celestron’s StarSense Explorer technology to aid you in navigating around the night sky with your smartphone. However, the focuser is only a single-speed unit and the only provided accessories are a 25mm Plossl eyepiece and red dot finder, which feels a bit lackluster considering that the StarSense Explorer 10” retails for a bit more than the price of the Z10. An 8” StarSense Explorer Dobsonian model is also available with the same features and accessories (or rather lack thereof) – but as with the Z10 vs. Z8 and similar models, we would recommend the 10” model as the weight and overall physical size are basically the same despite the 10” scope’s greater light gathering and resolution capabilities.
- The Explore Scientific 10” Truss Tube is significantly more compact than the Z10 thanks to its collapsible truss tube. It’s very similar to the cheaper 10” Hybrid model also offered by Explore Scientific apart from its open-frame upper tube assembly (which you could actually argue is a disadvantage as it needs a liner to keep dew and stray light out) and dual-speed 2” Crayford focuser as opposed to the Hybrid’s single speed. However, given the high price tag, it’s cheaper to just augment the Hybrid to compensate unless you care about having the paramount of portability possible for a 10” Dobsonian (the included accessories are still, of course, terrible).
- The Celestron NexStar 6SE is far and away less capable than the Z10 thanks to its lesser aperture and is arguably even inferior to the much cheaper, equal-aperture Sky-Watcher Virtuoso GTi 150P. However, if you must have a telescope with a tripod and some astrophotography capabilities, the 6SE is a good pick and still remains fairly portable while retaining enough aperture to be somewhat exciting, at least when it comes to the views of brighter targets like the Moon, planets, and star clusters.
Aftermarket Accessory Recommendations
The Z10’s included 30mm and 9mm eyepieces are enough to get you started, but at the very least, you’ll want something else for higher magnification. The 6mm “goldline” or “redline” sold by a variety of manufacturers, such as SVBONY, is low in cost and quite popular, and will provide 208x with the Z10. For a bit more power, a 4mm Astromania will provide 312x, which will quite often be the limit under typical seeing conditions-plus, tracking by hand at higher power with anything other than a super wide angle eyepiece can be a pain. The Z10 is an expensive scope, and expensive eyepieces are great, but these two low-cost picks are just fine.
If you’re satisfied with your eyepiece collection at the higher magnification range, the next step would be something for medium power—a single eyepiece between 12 mm and 18 mm, or both 12mm and 8mm eyepieces will work. A 15mm gold-line eyepiece exists, but performs poorly with the steep f/5 light cone of the Z10. Our favorite is the 15mm Agena Starguider – it’s comfortable to use, sharp, and the 60 degree apparent field at least doesn’t feel like a soda straw.
A coma corrector would be a lovely accessory, but the budget coma correctors from a variety of manufacturers (often just rebrands of the GSO unit) are really not designed with visual astronomy in mind and often have ridiculous spacing requirements or reduce the overall sharpness of the view. A Tele-Vue Paracorr or the Explore Scientific HRCC is best; either will be expensive, and due to their high quality, they tend to rarely show up on the used market.
Another great accessory choice is a nebula filter, specifically an ultra-high-contrast filter (some people swear by an oxygen-III filter in addition to a UHC, but this is expensive and really only a necessity for advanced observers). A UHC filter doesn’t remove light pollution altogether, and won’t work on stars or galaxies, but for most nebulae it greatly blackens the sky background and increases the contrast by only letting through a handful of spectral lines of light – the same spectra produced by the ionized gasses in nebulae. Even under dark skies, this contrast enhancement is helpful. We recommend the Orion UltraBlock 2” UHC filter for this purpose – with 1.25” eyepieces, you can just screw the UltraBlock onto the Z10’s 2” to 1.25” adapter thanks to its built-in filter threads.
Lastly, as we’ve mentioned, you’ll almost certainly want a zero-power red dot finder or reflex sight, which projects a dot or bullseye much like a gun sight in front of your naked-eye view of the sky. The two leaders in this department are the Telrad and Rigel Quikfinder. The Telrad is a big empty box that runs on AA batteries. The Rigel Quikfinder, on the other hand, is lighter, less likely to fog up, and takes up less space on the tube, but it needs rare CR2032 batteries and the reticle moves when you move your head, making it less accurate. Either one attaches to your tube without drilling with the included sticky tape, though drilling a hole and adding screws is a more secure mounting option if you’re comfortable doing it.
What can you see?
The Zhumell Z10 is an extremely capable instrument thanks to its large aperture and high-quality optics. Contrary to popular belief, big Dobsonians’ “light bucket” status doesn’t just help on deep-sky objects, but also enables greater resolution on small targets such as the planets and details on the Moon, though a telescope larger than 12-14” rarely gets to flex the full resolution capabilities it can truly offer due to the limits of atmospheric conditions most of the time.
With regards to Solar System targets, you’ll be able to see Mercury and Venus’ phases, but little else of them. Mercury is rarely able to be viewed when it’s high in the sky and has few high-contrast features, while Venus’ cloud deck obscures its near-molten surface – though some observers can see striations and dark markings in the clouds on some occasions. The Moon shows details less than a mile wide (no, you can’t see the Apollo landing sites) – you’ll struggle to even count how many craterlets you can see in regions like Clavius. Mars shows an ice cap or two, and if there’s a global dust storm, you’ll see it. Under optimal conditions, when Mars is at its closest to Earth, you can actually spot dozens of dark markings or even Olympus Mons with a skilled eye and steady air, but most of the time only a few are visible. Mars’ moons can also be seen if you can block out the planet’s glare from the field of view; Deimos is moderately challenging, but few people ever get to see Phobos.
Jupiter’s cloud belts are an easy catch with the Z10, and its moons are obviously tiny disks, though seeing details on any of them is really a job for a bigger instrument. Shadow transits of the moons across the face of Jupiter occur regularly, and the Great Red Spot is also no challenge to see. Saturn’s rings are similarly easy to spot, as is the Cassini Division within them and some faint cloud bands on the planet itself. Around a half dozen of Saturn’s moons are visible with the Z10, with Titan having a visibly gold disk. On a really good night, the much more challenging Encke gap in Saturn’s rings can also be seen. The Z10 will show you 3 or 4 of Uranus’ moons if you’re lucky, while both of the ice giants are bluish, featureless dots. Triton, one of Neptune’s moons, can be seen dimly, and Pluto could be seen if you could tell it apart from the hundreds of other dim stars in the area where it is now, in the constellation Sagittarius. Ceres and Vesta, the two largest asteroids, are visibly not star-like points on a good night, and you might even be able to tell that Vesta is not round and appears a gold-yellow color.
The visibility of targets outside the Solar System—what are known as “deep-sky objects”—strongly depends on your light pollution conditions. Galaxies in particular are affected severely: at a dark sky site with the Milky Way clearly visible overhead, the Z10 will show you the details of thousands of galaxies and the beautiful spiral arms of several dozen of them, while under a city sky, only the brightest galaxies can be seen as pale, dim shadows of their former selves, with little to no detail visible beside the occasional dust lane or elongated ovoid shape.
With the Z10, emission nebulae like Orion (M42) or the Lagoon (M8) look great, especially under a dark sky or with a filter, but they are still beautiful. Dozens of colorful blue and green planetary nebulae can also be seen, as can larger (albeit less vivid) ones like M27, the Dumbbell, and M57, the Ring. The Z10 is also big enough to see several dozen globular star clusters, including most of the ones in the Messier catalog. You can also see thousands of beautiful open star clusters, from the huge Pleiades, which have a faint glow of dust that can be seen in dark, clear skies, to small, obscure open star clusters from the NGC or IC catalogs that may be embedded in larger objects. Plus, there are always double stars, of which tens of thousands are resolvable and many of which tend to have interesting colors.