The Optical Tube Performance Of Z12
The Z12 is a 12” f/4.9 Newtonian reflector. While a 12” f/4 would be better portability-wise, the designers at GSO elected to make the scope as close to f/5 as possible so that you could get away with not using a coma corrector at first. We would recommend eventually obtaining a coma corrector for the scope as it is definitely visible at the edge of the field of view with low-power eyepieces such as the 30mm SuperView.
The primary mirror sits on a 9-point floatation-support mirror cell. Like with the other Zhumells the Z12 comes with 3 pointless locking bolts that can be removed to no adverse effect – they directly contact the glass and could crack your primary mirror if you drop the scope by accident with them left in, and serve no functional purpose in the scope.
The cell also has a cooling fan which is powered by an AA battery pack that plugs into the fan. I’m not sure where one is supposed to attach the battery pack – no instruction on that is given as far as I’m aware – but I wound up using Velcro to stick it onto the back end of the one I used.
The focuser on the Zhumells is a high-quality dual-speed 2” Crayford unit, a must for such a large scope with a fast focal ratio.
Unlike with the Z8 and Z10, the dust cap on the Z12 actually has raised areas near the middle for you to lift it off the tube, a nice bonus.
The Z12 Dobsonian Mount Abilities
The Z12’s mount works much like the Z8’s – the altitude bearings are small, adjustable ball bearings that can be slid up and down the optical tube to help with balance, while the azimuth bearing runs on rollers. The whole thing is constructed out of laminate-covered particle board and can be assembled with an Allen key in minutes – something you may need to do more than once if you plan on frequently transporting it.
Reviewing the Accessories
The Z12, like the Z10 and Z8, comes with a 30mm SuperView eyepiece (51x), 9mm Plossl eyepiece (169x), a laser collimator, and a 9×50 right-angle correct image finderscope.
The 30mm SuperView is decent, providing a 70-degree apparent field of view (so about 1.375 degrees true field with the Z12). However, in addition to the obvious and inevitable coma you’ll see at the edge of the field of view, the SuperView design suffers from a fair amount of edge-of-field astigmatism as well – though coma is a far bigger problem and a far more solvable one. The included 9mm Plossl is short on eye relief and has a narrow apparent field of view (I question if it’s even 50 degrees) but works quite well.
The included laser collimator works quite well, provided the laser itself is aligned. Unfortunately, this rarely proves to be the case, but aligning the laser is rather simple and can be done with an Allen key and a makeshift V-block in just a few minutes.
The included 9×50 RACI finder works great and allows you to see many faint fuzzies and dim stars directly – making locating targets a breeze under even light-polluted skies, though you may want a red dot finder or reflex sight to aid you in initially aiming it, as we’ll talk about below.
Should I buy a Used Z12?
If the price reduction compared to buying new is fair, then go for it. If the particle board mount is damaged or warped, you can make a replacement out of plywood fairly easily – or buy one. Make sure that the optics have no damage and that the coatings are in good shape.
If you’re not comfortable with moving the Z12 around, there are several alternative scopes that would make great picks:
- Meade Lightbridge Plus 12” – Same great performance but can be dismantled into significantly smaller and lighter pieces.
- Zhumell Z10/Apertura AD10/Orion SkyLine 10 – Smaller, but same great value and simplicity.
- Orion XT10i – A bit smaller, but more portable and with computer assistance in locating deep-sky targets.
- Meade Lightbridge Plus 10” – Smaller but significantly more portable.
Aftermarket Accessory Recommendations
The Z12 comes with a lot of great accessories, but there are a few we’d recommend to enhance your experience even further.
A 6mm “goldline” eyepiece will provide 250x with the Z12, which is a good magnification to use on most nights for the Moon, planets, close double stars, globular clusters, and planetary nebulae. For even more magnification, we’d recommend a 4mm planetary eyepiece for 375x. If you’re looking for a more moderate magnification eyepiece to fit between the included 30mm and 9mm, a 15mm redline (100x) is always a good choice for moderate magnification on the Moon and many deep-sky objects.
For viewing nebulae, a UHC filter is a great way to increase contrast under light-polluted skies. A 2” filter can thread onto the included 2” to 1.25” adapter for use with 1.25” eyepieces.
What can you see?
The Z12 is capable of showing you a lot. We mean it. Even within the Solar System, there’s a ton.
Mercury and Venus will show their phases as in a smaller telescope (that’s all there is to see of them, after all).
The Moon is lush with detail, and you’ll definitely want to use the included moon filter – you’ll be dazzled and have trouble seeing anything for a few minutes after viewing if you don’t!
Mars will show quite a few dark regions as well as the ice cap when it’s near opposition. With some special observing tricks to hide Mars and its glare from the field of view, you may even be able to spot its tiny moons Phobos and Deimos.
Jupiter’s cloud belts and Great Red Spot show a wealth of detail. Its 4 large moons are all easily distinguishable as disks with different colors. Ganymede in particular might have a bit of a two-toned look – gray on one side with more of a brown patch on the other. This brown spot is known as Galileo Regio.
Saturn and its rings are simply jaw-dropping through the Z12. The rings’ Cassini Division is quite obvious, and on a night of really good seeing, you might just be able to make out the Encke Division too. Saturn itself displays cream, beige, and gray cloud belts. More than half a dozen moons are easily visible, and with luck, you may be able to spot faint Hyperion.
Uranus and Neptune are still the same boring teal and bluish dots that they are in almost any telescope with the Z12, but with the exciting addition of moons. Neptune’s sole large moon Triton is fairly easy to spot, while Uranus’ 4 large moons – Titania, Oberon, Ariel, and Umbriel – will require fairly dark skies and a trained eye to see – they’re about as dim as Pluto.
Pluto is actually visible with the Z12 under decent skies – albeit as little more than a dim point. As Pluto will wander among the crowded star fields of Sagittarius for the foreseeable future, you may have a hard time distinguishing it from stars. Careful observation – either by comparing with simulations of the surrounding stars or by sketching it and watching for movement over the course of a few days – will be required to be sure you’ve bagged it.
For the best deep-sky views, you’ll really want to bring your Z12 to dark skies; if you can, expect the following:
Galaxies – Most of the Messier catalog galaxies and the brighter NGC ones show detail in some way – be it M31 and M64’s dust lanes, M82’s filaments, M33’s H-II regions, or M51 and M101’s spiral arms. Technically, these targets are all visible in a smaller scope under the right conditions too, but the Z12 really brings them out for even a novice observer. What’s more is that tens of thousands of additional galaxies are visible as faint or barely-noticeable smudges – some billions of light-years away.
Speaking of targets billions of light-years away, a 12” scope can show you a lot of quasars. Around a dozen quasars are brighter than magnitude 15, with the brightest – 3C 273 in Virgo – sitting at magnitude 12.9, which is quite easy under even rather light-polluted skies. PKS 0405-123 in Eridanus is 6.4 billion light-years away! They may appear as nothing more than dim star-like points, but quasars are the most distant objects visible to an amateur telescope, largely due to their extreme brightness compared to regular galaxies.
Globular star clusters – Even the fainter/smaller globulars are resolvable into individual stars. Some begin to take on some individual characteristics – for instance, M13’s dust lanes, M92’s oval-shaped appearance, M4’s loosely arranged stars, and the bright condensed core of M15.
Open star clusters – Open clusters explode into life in the Z12 even under city skies. Clusters such as M35, M11, M24, or the Double Cluster glitter with yellow, red, white, and blue stars. The brilliant blue Pleiades are dazzling to the eye – and with effort and dark skies, you may be able to begin to trace the faint reflection nebula that gleams within them.
Emission nebulae – M42 (Orion) and M8 (the Lagoon) have a green-blue color (mainly because our eyes are far more sensitive to blue/green than the reddish-pink light that actually dominates the nebulae) and look almost three-dimensional. You could spend hours on either of these two alone. The Swan Nebula (M16) shows loops of gas beyond the body of the “swan” and looks fabulous, as does the Trifid with its dust lanes. You can navigate around the enormous and complex Veil Nebula for hours with a good UHC or Oxygen-III filter.
Planetary nebulae – Most of the popular planetary nebulae show structure and/or colors in a 12” – ranging from simple rings to complex looping arrangements, and generally teal to deep blue coloration. The smaller planetary nebulae do require good seeing and high magnification to spot detail in, however.
Transporting & Setting Up The Z12 – Important Notes
The Z12’s optical tube is so large (at 14” across and 58” long) and heavy (at about 48 pounds) that careful considerations must be taken in moving it.
For one, unlike with the Z8 and Z10, the Z12’s tube will not fit across the back seat of most cars – fold-down seats are required. While the weight may not be bothersome to some people, the sheer width and length means you are going to have trouble “bear hugging” the scope to move it and there aren’t really any handles on the tube. Setting the scope precisely on the base without dropping it can also be a little tedious due to the small size of the altitude bearings and the precision at which they must be inserted into the base. The best option is to obtain aftermarket tube straps, or plan on hauling the tube (or entire scope) on a dolly or hand truck.
The particle board base of the Z12 weighs in at 38 pounds. Moving the base is awkward more than anything else, and the odd position your arms may need to take to lift it may cause you to get tired of carrying the base around after a while. You can buy or make a plywood base to significantly reduce the weight for a relatively low cost, and I would highly recommend doing so.