The Optical Tube
Sky-Watcher’s Skymax 127 optical tube, nominally a 127mm (5”) f/13 Maksutov-Cassegrain with a 1500mm focal length, serves as the mid-range option within the Skymax line of Maksutov-Cassegrains. The Skymax 127 shares identical specifications with other “127mm” Maksutovs offered by Celestron, Sky-Watcher, and several other brands. However, it differs slightly from the 127mm models provided by Bresser, Explore Scientific, and Meade, which feature a marginally different optical design and a true 127mm aperture. In practice, the primary mirror of the SkyMax 127 Maksutov is slightly undersized, stopping it at about 120mm in aperture. This minimal reduction makes the scope half an f-stop slower at f/12.5. The SkyMax 127 comes with a 1.25″ visual back that has a different thread system than Schmidt-Cassegrain accessories use. The included 1.25″ visual back also features built-in T-threads for attaching a DSLR camera. An aftermarket adapter can be purchased for using Schmidt-Cassegrain visual backs, adapters, or a 2″ diagonal. However, a 2″ diagonal will vignette significantly and usually isn’t worth the effort for the marginal useful field of view gained from using 2″ oculars with this scope. An f/6.3 reducer meant for Schmidt-Cassegrains will vignette severely and should not be used with SkyMax telescopes.
Focusing with the Skymax 127 is achieved by turning a knob on the rear of the scope, which moves the primary mirror back and forth along a rod within the tube. In larger telescopes, this process can cause image “shifting” and the appearance of wobble while focusing. However, the Skymax 127’s primary mirror is so small and lightweight that this issue is rarely encountered. As the secondary mirror on the Skymax 127 is fixed in place, like all Maksutov-Cassegrains, there is no need or ability to collimate it. Nevertheless, if required, a set of screws on the back of the scope can be adjusted to align the rear cell with the primary and secondary mirrors.
It is important to recognise that a long-focus scope is not a wide-field deep-sky instrument by nature, even if 2″ eyepieces could be used practically with the Skymax 127. Maksutov-Cassegrains are primarily designed for planetary observation. The advantage of an f/12.5 focal ratio is that nearly any eyepiece will deliver a sharp image, even Plossls or Kellners. For “wide” fields at low power, there is no need for sophisticated well-corrected oculars; an inexpensive “SuperView” or “superwide” based on the Erfle design is sufficient. Orthoscopics and quality Plossls offer incredibly sharp planetary views on a modest budget. These eyepieces are also usually lightweight and compact, making them ideal for travel; a large padded eyepiece case is not necessary when using the Skymax 127 (which itself can fit in a backpack).
Due to its thick corrector plate, the Skymax 127 requires more time to cool down to ambient temperatures when taken outside from a warm indoor environment, as compared to another scope of this size, such as a Newtonian reflector. In extreme cases, this process can take up to half an hour. Although one could wrap the optical tube in reflective insulation or invest in an electric cooler to expedite the process, both solutions are likely overkill for this aperture size. Cooldown time is a more significant concern for larger scopes.
The Skymax 127 comes with a standard Vixen-style dovetail plate affixed to the bottom of the tube, allowing it to slide onto the Virtuoso GTi mount’s corresponding saddle. Multiple ¼ 20 holes are positioned at various points to attach to a standard tripod head if needed. Both options are suitable for mounting the Skymax 127.
The Sky-Watcher Skymax 127 Virtuoso GTi comes with the same set of accessories as the GTi 150P, Heritage 150P, and 130P—a battery-powered red dot finder for aiming the scope and aligning its mount, a 90-degree prism star diagonal, and a pair of 1.25″ “Super” eyepieces with 25mm and 10mm focal lengths, yielding 60x and 150x magnification respectively. These eyepieces are lightweight and plastic-bodied but well-made, with all-glass optics of the Konig configuration that work perfectly at this scope’s f/12.5 focal ratio and offer more eye relief than a standard Kellner or Plossl. The 10mm Super eyepiece is quite comfortable to use compared to the 10mm or 9mm Plossl/Kellner provided by most manufacturers.
The Virtuoso GTi Mount
The Virtuoso GTi mount is a tabletop Dobsonian alt-azimuth mount that moves in altitude (up/down) and azimuth (left/right). It is designed for both manual and computerized use thanks to its motor drives and clutches on both axes. These clutches can be disengaged, enabling you to direct the Virtuoso GTi around the sky by pushing it as you would a conventional tabletop Dobsonian. Alternatively, you can secure the clutches, switch on the mount and operate it via your smartphone or tablet through the mount’s integrated WiFi network, using either the complimentary SynScan app or alternative astronomy applications such as SkySafari Pro or Stellarium. With a simple press of a button, the Virtuoso GTi will traverse the sky, offering access to tens of thousands of potential targets, while automatically tracking the sky.
Moreover, it is possible to disengage the Virtuoso GTi’s clutches, manually aim the telescope and utilise solely the tracking feature or revert to the GoTo system at any given moment without impacting the scope’s star alignment, even when manoeuvring the scope by hand. This dual encoder technology is marketed by Sky-Watcher under the “FreedomFind” label and is now incorporated into the majority of their product range.
It is essential for the Virtuoso GTi mount to be positioned on an exceptionally stable tabletop surface, not only to ensure comfortable viewing but also to maintain the alignment of the GoTo system. Attempting to manually direct the telescope on an unsteady table can be exasperating and will likely compromise the precision of the motors, leading to an overall frustrating experience. A bar stool or milk crate is well-suited for use while standing or sitting, respectively. Alternatively, you can construct a stand for the Virtuoso GTi or any other tabletop telescope with minimal expenditure by employing basic carpentry tools and materials. The base of the mount also features a standard threaded ⅜” socket, allowing it to be affixed to a sufficiently robust photographic tripod if you have one, though this may not be economical compared to buying the Skymax 127/AZ-GTi combination if you don’t already possess a beefy tripod to attach the Virtuoso to.
Should I buy a Used Sky-Watcher SkyMax 127 Virtuoso GTi?
Discovering a second-hand Sky-Watcher SkyMax 127 Virtuoso GTi might prove to be an unusual occurrence, as would stumbling upon one in poor condition, given that these telescopes only started production in 2022. There’s fairly little to go wrong with the scope that isn’t immediately obvious to even the casual
The Sky-Watcher SkyMax 127 Virtuoso GTi is a good scope, but you may wish for a more capable scope – either a Dobsonian or a tripod-mounted catadioptric – instead.
Under £800 Range
- The StellaLyra 10″ f/5 Dobsonian boasts double the resolution and over four times the light-gathering capacity in comparison to the Skymax 127 Virtuoso GTi, due to its remarkable 10″ primary mirror. A range of accessories are included with the telescope, such as a 2″ low-power, 30mm focal length wide-angle eyepiece, a 9×50 finder scope, and a 9mm high-power Plossl eyepiece.
- The Celestron StarSense Explorer 8″ Dobsonian affords some computerised pointing capabilities, albeit without motorised tracking, through the use of its StarSense Explorer technology. Naturally, it boasts superior light gathering and resolving power to the Skymax 127 Virtuoso GTi, thanks to its 8″ aperture on a stable Dobsonian base. While the telescope is convenient to set up, transport, and utilise, the range of accessories it offers is comparatively limited.
- The Sky-Watcher Virtuoso GTi 150P provides a 50% increase in light-gathering ability, enhanced optics, a broader field of view, and marginally better resolution compared to the Skymax 127 Virtuoso GTi, utilising the same tabletop mount. Its collapsible tube facilitates easy transportation, and its short focal length presents a wide field of view, making it perfect for deep-sky observation. The Heritage 150P serves as a more cost-effective alternative, identical to the Virtuoso GTi 150P, but without the electronic components.
- The Sky-Watcher Skymax 127 AZ-GTi is identical in features, performance and accessories to the Skymax 127 Virtuoso GTi but with a more compact mount head and integrated tripod.
Over £800 Range
- The Celestron StarSense Explorer 10″ Dobsonian’s monster 10” aperture means you can enjoy four times the light-gathering ability and twice the resolving power of the Skymax 127 Virtuoso GTi. Celestron’s StarSense Explorer technology provides assistance in manually aiming this telescope around the night sky. Although the base is relatively lightweight for a 10″ Dobsonian, transportation is made even easier with cutouts in the base and handles on the tube. Despite offering minimal accessories in addition to the StarSense Explorer technology, this telescope provides excellent value in terms of aperture and portability for its price.
- The Celestron NexStar 6SE offers greater stability compared to the Skymax 127/Virtuoso or AZ-GTi mounts (albeit with a slightly less user-friendly hand controller) and delivers similarly sharp views of the Moon and planets. Thanks to its larger aperture, it also provides superior deep-sky views, and, when equipped with a focal reducer and attached to an equatorial mount, boasts some deep-sky astrophotography capabilities.
- The Sky-Watcher Skyliner 250P FlexTube GoTo Dobsonian not only features double the resolution and four times the light-gathering power of the Skymax 127 Virtuoso GTi, but also offers full motorised tracking and GoTo capabilities. Moreover, Sky-Watcher’s FreedomFind encoder system allows you to aim the telescope manually without affecting the alignment or motors in the mount.
- The Celestron NexStar Evolution 6 shares similarities with the NexStar 6SE, as both incorporate the C6 XLT optical tube. However, the Evolution 6 offers various mechanical enhancements compared to the more affordable NexStar 6SE. In addition, it includes a built-in Wi-Fi adapter and lithium battery, simplifying setup and usage.
Aftermarket Accessory Recommendations
A dew shield for the Skymax 127 Virtuoso GTi is an extremely useful accessory that can reduce glare at the eyepiece and improve contrast, slow down frost or dew formation on the scope’s front corrector plate, and also protects the corrector from fingerprints, pollen, and other common causes of damage to the sensitive optical coatings. Additional eyepieces can also be beneficial, such as a 32mm Plossl eyepiece for 47x magnification, providing a slightly wider field of view and lower magnification than the provided 25mm eyepiece, making it more suitable for viewing deep-sky objects.
Moreover, it might be worth replacing the Skymax 127 Virtuoso GTi’s stock 10mm eyepiece with a 9mm redline or goldline ocular (167x) for slightly more magnifying power, sharper views, greater eye relief, and a wider field of view. A 7mm planetary eyepiece (214x) will maximize the SkyMax 127’s usable magnification on a steady night, while a 15mm redline or goldline (100x) fits midway in magnification and focal length between the Skymax 127 Virtuoso GTi’s included pair of eyepieces, although you may or may not end up using it frequently.
What can you see?
The Skymax 127 is predominantly designed for observing the Moon, planets, and double stars. Naturally, you can witness the phases of Mercury and Venus, and Mars will display its polar ice cap at the very least. During Mars’ opposition and close proximity to Earth, you should be able to discern a number of dark markings on the planet’s surface, provided atmospheric conditions permit. The Moon reveals features as narrow as a few miles, with a range of regions exhibiting high contrast depending on the Moon’s precise phase. Within the large crater of Clavius, you should be able to resolve dozens of small craterlets.
All four of Jupiter’s moons are of course easily visible with the Skymax 127, and they should appear as tiny discs, although this becomes an easier task when they transit in front of Jupiter. Jupiter’s cloud belts exhibit a diverse range of colours, from grey to blue, red, tan, brown, and even pink. The Great Red Spot can be resolved at high magnification, as long as it is on the side of Jupiter facing Earth when you observe it. However, it might be somewhat challenging to differentiate it from the adjacent South Equatorial Belt, which often exhibits a similar, if not identical, colour.
The rings of Saturn look spectacular with the Skymax 127, and during good seeing conditions, you should have no trouble resolving the Cassini Division within the rings. Saturn’s several cloud belts, displaying slightly different colours, should also be visible. Approximately half a dozen moons, appearing as dim star-like points, can be observed around Saturn, as long as light pollution is not too severe. Uranus and Neptune present themselves as small, bluish dots, with both resembling a fuzzy “star” in appearance. Observing Neptune’s moon Triton with a telescope of this modest aperture is an extremely challenging task, though not impossible. Pluto, on the other hand, remains elusive.
The Skymax 127 also excels in the observation of double stars, resolving them to their theoretical limit thanks to its sharp Maksutov-Cassegrain optical design. In contrast to a Newtonian reflector, no diffraction spikes are present. The smaller central obstruction, compared to a Schmidt-Cassegrain, and superior quality control of the optics result in sharper, pinpoint stars. Additionally, you can disregard the chromatic aberration that most refractors of this size – particularly the more affordable ones – are likely to exhibit.
When it comes to deep-sky objects, the Skymax 127 falls somewhat short in performance on many targets. A 120mm aperture lacks the necessary resolving power or light-gathering capacity to resolve all but a handful of the brightest globular star clusters such as M3, M13, and M22. Likewise, you probably won’t have luck observing details in most galaxies with this scope, especially if you’re a beginner. When you consider this combined with the SkyMax 127’s naturally limited field of view for larger and brighter targets such as open star clusters and nebulae, there are undoubtedly telescopes of a similar aperture or price range that are better suited for deep-sky observation. You can still glimpse dust lanes in a few of the brightest galaxies, such as Andromeda (M31), or examine groups like the Leo Triplet and Virgo Cluster, but temper your expectations, particularly if you reside under light-polluted skies where visibility becomes even more challenging.
The Virtuoso GTi mount, being an inexpensive and lightweight alt-azimuth design, coupled with the SkyMax 127’s f/12.5 focal ratio, renders it utterly ineffective for deep-sky imaging. Nevertheless, it is quite possible to achieve satisfactory imaging of the Moon and planets with the aid of an affordable CMOS planetary video camera and a 2x Barlow lens. The only additional requirement is a laptop equipped with a substantial amount of RAM and ample hard drive storage capacity.