The Optical Tube
The Skywatcher Skyliner 350P FlexTube GoTo Dobsonian is a 14” (356mm) f/4.6 Newtonian reflector with a focal length of 1650mm. At f/4.6, coma is evident with wide-angle 2” eyepieces, and cheaper oculars will also display additional aberrations such as edge-of-field astigmatism, which will wreck the view too. 2” wide-angle “SuperView” and “SWA” type eyepieces are going to be a bit of a mess on such a fast instrument. You will ideally want to use well-corrected UWA/Nagler or XWA/Ethos type eyepieces, as well as possibly a coma corrector, for sharp low-power views. Likewise, collimation is fairly critical; a good laser collimator or Cheshire will be necessary, and you should expect to have to re-collimate the primary mirror of the 350P FlexTube every time the tube is extended or collapsed.
Collimation of the SkyWatcher Skyliner 350P FlexTube’s primary mirror is adjusted with standard hand knobs at the back while the secondary is adjusted with a hex key; adjustment is so seldom needed that installing thumb screws is probably a waste of money and will likely lead to a more frequent need for re-collimating the secondary anyway. Our collimation guide provides more info, and our laser collimator and Cheshire articles go over the advantages/disadvantages of each as well as providing a few different product recommendations.
Focusing is also fairly stringent at f/4.6, especially at the typically high magnifications you will often find yourself using with this scope, but thankfully the Skyliner 350P FlexTube GoTo comes equipped with a nice dual-speed 2” Crayford focuser.
The Skyliner 350P FlexTube GoTo, as with its 16” counterpart and their Orion cousins, features a conical, ribbed primary mirror made out of low-expansion borosilicate glass. The conical primary mirror cuts down on weight as well as reduces the time it takes for the mirror to acclimate to ambient temperature; no fans are provided by default, but you can and should attach at least one fan to the back of the primary mirror to aid in cooling. The conical primary can cause some concern with “print through” of the ribs to the front optical surface, creating less-than-sharp images, but this mostly seems to be a problem with the larger 18” and 20” scopes, which Sky-Watcher has quietly stopped selling in most markets.
The Skyliner 350P FlexTube GoTo of course features the FlexTube design of three struts, which collapse in a few seconds. This reduces the telescope tube’s length from 60” to 38.5,” making it possible to fit the optical tube across the back of a car and only slightly longer than the 12” FlexTube when collapsed. However, at 53 lbs (24 kg), the Skyliner 350P FlexTube is heavier than even a solid-tubed 12” optical tube, and it’s still fairly awkward to carry around yourself despite the built-in handles. For comparison, the author’s entire 14.7” truss tube telescope weighs 53 lbs, with about 40 lbs being the tube, and being a truss, it disassembles into portions weighing no more than 25 lbs each. The Orion XX14i, which shares the entire design of the Skyliner 350P FlexTube apart from its fully deconstructible truss tube, has a lower tube assembly weighing 35 lbs. Truss tube scopes are also, of course, a lot less awkward to handle in their individual pieces. So while the FlexTube may be simpler and free of as many knobs or easily missing parts, you pay dearly in physical discomfort moving it around.
The Skyliner 350P FlexTube’s trusses have a second setting to provide enough in-focus travel for a binoviewer or camera, and it has plenty of back-focus nonetheless as it requires you to use an extension tube for most eyepieces, of which two are provided (a 1.25” and a 2″), as is the typical nonsense with Sky-Watcher’s extension tubes).
Attaching the Skyliner 350P FlexTube GoTo to its Dobsonian Base is fairly simple. You rotate the left-side bearing holder horizontally to line up with a slot in the left bearing attached to the tube, lower the tube onto the base horizontally (aimed at the horizon), and tighten a single knob to secure the bearing in place. The right side altitude bearing just pivots freely on a pair of plastic cylinders, like a manual Dobsonian.
The SkyWatcher Skyliner 350P FlexTube GoTo Dobsonian comes with typical 1.25” 25mm (66x) and 10mm (165x) “Super Plossl” oculars. These are nice enough eyepieces, and their well-corrected but narrow 50-degree apparent field of view means you won’t see a lot of issues with coma or astigmatism, but they are far from what you should probably be using with a scope of this size and cost.
The finder provided with the Skyliner 350P FlexTube GoTo is a 9×50 straight-through finder scope that has crosshairs, a roughly 6-degree true field, and a view that’s flipped upside-down. It is really only provided for aligning the GoTo system of the scope and is rather uncomfortable to use compared to a right-angle finder or reflex sight. Interchanging it with a lighter-weight red dot/reflex sight or a right-angle, correct-image finder is easy, thanks to the standard Synta/Vixen-style finder shoe.
The SkyWatcher Skyliner 350P FlexTube GoTo Dobsonian uses the same design as all of the other Orion/Sky-Watcher GoTo Dobsonians. At its core, being a Dobsonian, the Skyliner 350P FlexTubeGoTo is an alt-azimuth design, pivoting left-right and up-down, with a mount made out of wood. However, being motor-driven, there are, of course, a few changes. The scope’s optical tube attaches to a servo-driver altitude axis motor on one side and pivots on simple plastic pads like a conventional Dobsonian on the other bearing; this reduces the torque needed for the motor to move the scope and eliminates the need for a pair of them, as well as reducing setup time and weight. The azimuth axis is a roller bearing driven by another massive servo motor. Both the altitude and azimuth axis use slip clutches, allowing you to unlock them by turning knobs to point the whole scope manually. Dual encoders will tell the telescope where you have manually aimed it, allowing the motors to continue to find and track objects in the sky accurately—a feature many cheap GoTo scopes lack. Sky-Watcher terms the slip clutch/dual encoder combination their “FreedomFind” technology, but many other instruments have this ability.
The Skyliner 350P FlexTube GoTo comes with Sky-Watcher’s standard SynScan controller as well as a built-in WiFi adapter by default; the smaller scopes have either as an option. You have to pick between the hand controller or controlling the scope via your smartphone/tablet when you power it on. Using a device over WiFi is a little more intuitive, but some people prefer the feedback and closed system of the controller. Either one will require an alignment process, either a standard 2- or 3-star alignment or a less accurate “quick align,” which may be all you need if you just want motorized tracking while you putter around manually or simply want to enjoy viewing the Moon and planets.
The Skyliner 350P FlexTube GoTo’s base dismantles for transport, and the front and side boards detach from the ground/azimuth board with hand knobs in a few minutes. However, the massive ground board is about 54 lbs (24 kg) and 30” wide, with few points to grab—arguably worse to pick up and move than the optical tube itself, which weighs about the same amount. The most convenient way to move the ground board around is to simply roll it on its rubber-rimmed edge like a big tire, which can be a little disconcerting but works well enough as long as you avoid damaging the base or kicking up rocks or debris into the middle of the motor housing.
Mainly due to the additional height imposed by the azimuth motor housing, the height of the Skyliner 350P FlexTube GoTo’s focuser/eyepiece when aimed at the zenith is roughly 64” above the ground. This means that if you are less than six feet tall, you will need a step stool or short ladder to look through the eyepiece when the scope is pointed straight up, though for most of the sky, you can remain with your feet on the ground unless you are unusually short.
Aftermarket Accessory Recommendations
It is absolutely essential to purchase a stiff fabric shroud for the SkyWatcher Skyliner 350P FlexTube GoTo Dobsonian’s open tube, as is the case with almost any open-tubed strut or truss telescope. Without a shroud, glare from the Moon, nearby sources of light such as street lamps or passing cars, and the general glow of light-polluted skies will significantly impact contrast at the eyepiece, severely affecting the views through this telescope, especially those of faint deep-sky objects like nebulae and galaxies where maximum contrast and darkness are required to see anything at all. A shroud also mitigates the formation of dew and frost on the telescope’s dew magnet of a secondary mirror and will tend to keep your optics cleaner too.
You’re also going to be sure to want to replace the 350P’s included 3-element eyepieces, though with such an expensive telescope there are a myriad of options. However, we can certainly provide a few recommendations. A 28mm UWA (60x) or another high-quality UWA or XWA eyepiece in the 20-30mm range such as the Explore Scientific 82-degree or 100-degree line makes for an ideal low-power eyepiece, especially if coupled with a suitable coma corrector such as the Explore Scientific HRCC. If you’re not using a coma corrector, we’d recommend replacing the 350P FlexTube’s included 2” extension tube with one that utilizes a compression ring adapter, and you’ll likewise want to do the same for a replacement 2” to 1.25” adapter and obtain one with filter threads so 2” filters will fit your 1.25” eyepieces. A good cheshire collimation tool is also a must.
For higher magnifications, we would recommend at least another 2 or 3 eyepieces, such as a 16mm UWA (103x) and 7mm UWA (235x), for the 350P, along with something like a 4mm UWA or planetary eyepiece (413x) if your atmospheric conditions permit such high magnifications. Additional eyepieces besides these might also be a good idea.
Additionally, using a high-quality narrowband Ultra High Contrast (UHC)/OIII nebula filter can greatly improve your views of nebulae, such as the Orion Nebula, with almost any telescope, including the Skyliner 350P FlexTube GoTo Dobsonian. This filter also enhances the visibility of planetary nebulae by dimming the brightness of nearby stars, making it more straightforward to locate them at low power. Furthermore, it offers sufficient contrast enhancement to uncover previously unseen nebulae, like the Crab Nebula, Crescent Nebula, Veil Nebula, or Flame Nebula, when using the Skyliner 350P FlexTube GoTo Dobsonian under dark skies. A 2″ nebula filter can be connected to an aftermarket threaded 1.25″ adapter, as mentioned earlier, ensuring compatibility with either size eyepiece.
Should I buy a Used Skywatcher Skyliner 350P FlexTube GoTo Dobsonian?
The SkyWatcher Skyliner 350P FlexTube GoTo Dobsonian is a great scope, though if you’re buying a used one, some caveats apply. Any damage to the particle board base or electronics will ruin GoTo functions, while damage to the tube could inhibit the function of the FlexTube struts or the scope’s ability to hold collimation. Be sure to check that the mirrors are also free of corrosion or other damage.
What can you see?
The SkyWatcher Skyliner 350P FlexTube GoTo Dobsonian’s primary mirror has about 36% more light gathering ability than a 12” aperture. As such, it is ideal for viewing deep-sky objects, though as always light pollution will affect what you can see, in the worst cases outright ruining the views of all but the brightest objects. Open star clusters delight with colorful stars even under brightly light-polluted skies with the Skyliner 350P FlexTube GoTo Dobsonian. Dimmer globular clusters are a bit easier to resolve, while the brightest ones easily pop into view at low power. Galaxies show dust lanes and features such as H-II regions and spiral arms under dark skies, with hallmark objects like M51, M82, and M31 appearing simply fantastic under good conditions. Galaxy clusters such as the Virgo Cluster and dimmer ones found throughout the sky can display dozens or even hundreds of members in a single low-power field of view. Emission nebulae like Orion (M42) and the Swan (M8) display jaw-dropping detail and even hints of color under dark skies, while further detail can be brought out with a UHC nebulae filter. A UHC filter also reveals spectacular detail in the Veil and numerous other nebulae. Planetary nebulae, meanwhile, show intricate, tiny details under good seeing conditions with the Skyliner 350P FlexTube GoTo Dobsonian and an array of colors from blue to green, red, and even yellow-gold. Good seeing as well as dark skies are required to see planetary nebulae at their best, however.
The Skyliner 350P FlexTube GoTo Dobsonian is also great for lunar and planetary viewing. If you are stuck under poor seeing conditions, you can make an off-axis mask out of cardboard for the telescope to produce a 5.5” f/11 unobstructed instrument that will beat even a high-end refractor and likely display sharper images than the full aperture of the scope. However, should your atmospheric conditions permit, the full resolving power of a 14” telescope is spectacular for viewing fine detail on the Moon; features just a few hundred meters wide can be seen, such as ridges or mountain peaks. Mercury and Venus show little detail to the eye besides their phases (though imaging can bring out some low-contrast shading detail). Mars’ surface shows its polar ice caps, any ongoing dust storms, and myriad dark markings when the planet is close to Earth.
The Skyliner 350P FlexTube GoTo Dobsonian will allow you to make out all sorts of colorful and ever-changing details in Jupiter’s turbulent atmosphere, including the main equatorial cloud belts and the Great Red Spot. You can also resolve the four largest Jovian moons as tiny disks, with Ganymede displaying one or two surface features and hints of shading on Io and Callisto on the best of nights and all four displaying obvious shadows during the occasional transit. Saturn’s rings are spectacular, with the Cassini Division easily resolved within them, along with possibly the Encke gap in the rings on an exceptional night and a half dozen moons scattered around the planet. Uranus’ greenish-blue disk may show atmospheric details under very good conditions, and up to four of its faint moons may accompany the ice giant, while Neptune’s fuzzy blue disk and its moon Triton are clearly visible. A 14-inch telescope also has no trouble picking up Pluto under dark skies if you are looking in the correct place.
The motorized tracking of the SkyWatcher Skyliner 350P FlexTube GoTo Dobsonian combined with its huge aperture makes it an ideal platform for planetary astrophotography, besting even the largest catadioptric telescopes typically used by lunar and planetary imagers (it is a poor choice for deep-sky astrophotography, however). A color, high-speed planetary CMOS camera like the ZWO ASI224MC and a 5x Barlow lens are ideal for achieving the sharpest possible images, with just a few minutes of footage often needed for spectacular shots.