The Z8 Optical Tube Overview
The Z8 is fairly standard in optical quality among all of the 8” Dobsonians out there (which is unsurprising, since there are only two different OEMs for them). Some literature claims that the Z8 has enhanced reflectivity coatings with 94-96% reflectivity compared to the standard 89–93% reflectivity on most coatings, which would theoretically give it brighter images. A proper laboratory test would be required to be sure, as the effect would be negligible in observations.
The Z8’s mirror cell is collimatable and uses springs, but there are also 3 “mirror lock” bolts on the back. Supposedly, these are to compensate for any weakness in the springs, but the springs can handle the mirror just fine, and they could always be replaced if necessary. The mirror locks really just serve as a great way to get confused while collimating, or break your mirror if you drop the scope (since the locking bolts directly contact the glass). Just remove them.
The Z8 has a built-in DC-powered cooling fan that runs off a small battery pack supplied with the scope.
The Z8’s front cap is a bit of a weak point with this scope. It is not very tight-fitting and there is nowhere to grab it from the middle. However, this is a minor inconvenience at most and can be solved with a trip to the hardware store for a cabinet knob and drilling a hole or two.
The tube of the Z8 is longer than that of some other 8” scopes on the market, such as the Synta-made Dobsonians marketed by Sky-Watcher (Classic Dobs), Orion (SkyQuest Series), and Bintel among others. As such, it may not fit in the trunk or boot of some cars and must be laid across the backseat.
The Z8 comes with an extremely high-quality dual-speed Crayford focuser. This focuser (like all Crayfords) rolls the focuser drawtube against 4 rollers for precision and smooth motion. The dual-speed part comes from the fact that it has a 1:10 fine adjustment knob for precision focusing at high magnifications. It also uses a brass compression ring so as to not mar your eyepiece barrels (as does the included 1.25” adapter).
The Zhumell Z8 Accessories
RECOMMENDED BUY FOR THE BEST VALUED ACCESSORIES
The Z8 comes with a 50mm right-angle, correct-image finderscope, a laser collimator, a Moon filter, and two eyepieces: a 30mm, 2” “SuperView” and 9mm, 1.25” diameter Plossl. They are all fair offerings for the price.
The 9×50 right angle correct image finder is decent but can be difficult to use. You have to sight along the barrel of the finder/telescope then look into the finder itself to center your target. It’s best supplemented with or replaced by a zero-power reflex or red dot sight.
The included laser collimator is really well-made. However, the laser itself is frequently misaligned with the barrel, making it useless. This can be solved by making a makeshift V-block and adjusting the tiny Allen screws in the collimator – tricky, but worth it.
The included 30mm SuperView is a decent low-power eyepiece, based on the Erfle design. While there is some edge-of-field astigmatism, the 70-degree apparent field of view and the 40x magnification it provides with the Z8 make it great for low-power viewing of deep-sky objects. The included 9mm Plossl works okay, but you have to press your eyeball right up to it to see the entire field.
The “Moon filter” is little more than a piece of cheap green-tinted glass, not a true polarizing filter. It will dim the moon, but you probably don’t need it, and if you must have a moon filter, there are much higher quality ones available.
A Better Dobsonian Mount Design
The Zhumell/GSO Dobsonians are a bit different from your typical Dob in their mountings, but the changes are at least somewhat for the better, if a bit strange compared to other offerings.
For one, the altitude bearings are far different from pretty much any other Dob. Instead of using Teflon pads, the Z8’s altitude bearings are ball bearings that can be adjusted for tension and can slide along the tube for balancing. You can achieve balance with some pretty heavy accessories on the front end as a result, but the balance tends to go out of whack if you switch from heavy to light eyepieces, which requires tightening the bearings and thus sub-optimal movement. Adjusting the center of gravity of the bearings requires tools and really can’t be done in the field.
Then there’s the azimuth bearing. Rather than Teflon on laminate, it’s a roller bearing, also known as a “lazy Susan,” which you might be familiar with on some furniture items. Many users swear by it. However, it is a bit loose and easy to spin compared to a normal Dobsonian bearing, which can be frustrating when trying to track at high power or on a windy night.
Like most mass-manufactured Dobs, the Z8’s mount assembles with just an Allen key and a handful of screws, a task that takes mere minutes to accomplish. It is, however, made of particle board, which is quite heavy and easily prone to moisture damage if the laminate covering peels off.
Should I buy a Used Zhumell Z8?
A used Z8 is a wonderful scope. Make sure the coatings on the mirrors are still good and the base isn’t damaged. If the base is damaged, replacing it is somewhat expensive but you can easily make a sturdier, lighter, and longer-lasting one out of plywood with just a few tools if you are so inclined.
If you must consider alternatives, know that the Z8 is one of the best telescopes in its price range, except for the Apertura replicas.
- The Zhumell Z10 (like the Z8, also sold under other brand names such as Apertura) offers the same features as the Z8 but with more aperture.
- The Sky-Watcher 8” Collapsible has similar optics to the Z8 but with a collapsible tube and slightly inferior accessories.
- The Orion StarBlast 6i has less aperture than the Z8, but has a much wider field of view and features Orion’s IntelliScope object locating system.
Aftermarket Accessory Recommendations
The Z8 comes with a lot of great accessories, but we’d still recommend a few more things to go with it.
For one, we highly recommend the 6mm Goldline eyepiece, such as the one sold by SVBONY. This will provide 200x magnification, a bit better for the Moon, planets, and double stars than the 133x provided by the included 9mm eyepiece.
Additionally, a zero-power reflex sight is a good idea. The Telrad or Rigel Quikfinder are both great choices. The Telrad is bigger but runs off standard AA batteries and is a bit easier to use, while the Rigel is compact and has a built-in dew shield.
Last is some kind of nebula filter. An ultra-high contrast or UHC filter is best; it cuts out almost all the light entering the eyepiece apart from the oxygen-III, hydrogen-alpha, and hydrogen-beta spectra emitted by the glowing ionized gases in nebulae. While it doesn’t negate the effects of light pollution, a UHC is quite helpful for viewing nebulae from light-polluted areas and will bring out contrast even under dark skies. We recommend the 2” Orion UltraBlock for this purpose.
What can you see with the Zhumell Z8?
The Z8 can show you a lot of stuff. You’ll be able to see Saturn’s rings, Jupiter’s cloud belts, and the numerous moons of both gas giants, and, of course, the Great Red Spot. On a good night, you can see some cloud details on Saturn and the Cassini Division in its rings too. Mars’ dark spots and ice caps, along with any dust storms, can be seen when the Red Planet is close to Earth. Venus and Mercury don’t show much besides their phases in any telescope, but they are usually quite sharp and pleasing to look at with the Z8 on a clear and steady night. Uranus and Neptune are pale bluish dots, but under dark skies, you might be able to spot their moons (which are nearly as faint as Pluto): Oberon and Titania around Uranus and Triton around Neptune. The moon looks fabulous too. Pluto is theoretically within reach with perfect conditions, but it’ll be a hard-to-find and very dim star-like point.
Outside the Solar System, what the Z8 can show you really depends on the quality of your skies. Under dark skies, you’ll be able to see details and structure in numerous spiral and irregular galaxies like M31, M51, M33, M82, and the Virgo Cluster of galaxies. The handful of emission nebulae like Orion, the Lagoon, and the Swan look fantastic, especially with that oh-so-handy nebula filter we recommend, which helps with enhancing their contrast against the background (though even unfiltered, they’re lovely). Planetary nebulae vary quite a bit; some, like the Dumbbell and Helix, are huge, colorless, and really benefit from a nebula filter, while smaller ones, like the Cat’s Eye, are beautiful green or blue in color and have a small-scale structure that benefits from using very high magnification. You’ll also have no trouble resolving many of the brighter globular clusters like M13 or M15 into individual stars, and many open clusters are colorful and splendid even under light-polluted skies. Keep in mind that galaxies and larger nebulae will nearly vanish or at least be heavily degraded under light-polluted skies, and a filter will not bring back the lost details or contrast (especially in the case of galaxies that are low in contrast to begin with).
Pricing and Availability
Zhumell Z8 was widely available at a price of $450 when this Zhumell Z8 review was first published in 2019. With the COVID-related supply chain interruptions and subsequent price spikes, those days are long gone. We believe that a price of less than $700 would be a reasonable price for a Z8 these days. In the United States, the Z8 is exclusively available via three retailers: High Point Scientific, Amazon, and TelescopesPlus. We’re of the opinion that High Point should be your telescope store pick for Z8 purchase, followed by Amazon and TelescopesPlus. You might want to compare the cost with that of Apertura AD8, though.