The Optical Tube
The Sky-Watcher Explorer 150PDS optical tube assembly comprises a 6-inch (150mm) f/5 Newtonian reflector with a 750mm focal length. Its specifications are similar to those of numerous other imaging Newtonian astrographs and 6-inch f/5 tabletop Dobsonians. As is typical of such telescopes, the optics in the Explorer 150PDS are of a high standard, and at f/5, coma is barely discernible at the periphery of the field when using a 1.25-inch eyepiece, although cheaper wide-angle eyepieces such as the provided 28mm 2” LET ocular may exhibit other aberrations at lower magnifications away from the field’s centre.
The 150PDS is equipped with a relatively simple 2-inch, dual-speed Crayford focuser. It doesn’t feature a compression ring to hold 2” accessories like the provided 2” LET eyepiece or the included 1.25″ adapter, and it might slip or sag somewhat under particularly heavy loads such as a beefy camera and coma corrector. However, for a typical DSLR or colour camera, this is a minor concern, and the focuser’s movements are impressively smooth. Furthermore, it easily accommodates a motor focuser add-on unit like the ZWO EAF.
Collimation is critical with any f/5 telescope, particularly one for astrophotography. The collimation of the Explorer 150PDS can be adjusted via a set of three spring-loaded knobs located at the back of the primary mirror (secured by an additional trio of locking screws), while the secondary mirror requires a hex key for adjustment. Our collimation guide offers a more in-depth exploration of the process. The telescope maintains its collimation rather well, but substituting the stock springs in the primary mirror cell with sturdier alternatives can further enhance its stability over time and when moved across the sky. The rear of the primary mirror cell features a 12V DC-powered 80mm fan, which aids in cooling the primary mirror down to ambient temperature more rapidly.
To facilitate attachment to a mount such as the supplied EQ5 Pro, the Explorer 150PDS is equipped with a pair of standard tube rings and a Vixen-style dovetail bar. The bar can be replaced with a Losmandy-style one if preferred, and it is recommended to affix a second dovetail to the top of the rings for enhanced rigidity and the mounting of additional accessories like a guide scope.
Accessories
You get one eyepiece with the Explorer 150PDS, a 2”, 28mm focal length Sky-Watcher L.E.T. 3-element ocular with a comfortable twist-up rubber eyecup. This eyepiece yields a magnification of 27x with the 150PDS, and has an apparent field of view of about 60 degrees which consequently yields a true field of a little over 2 degrees, or 4 times the angular diameter of the full Moon, with the 150PDS. Under brightly light-polluted skies, this may be too low of a power for the 150PDS and consequently provide a washed-out, gray-brown sky background, so an ocular in the 16-22mm focal length range is probably more appropriate for deep-sky viewing with the 150PDS (as are higher powers for lunar, planetary, and double star observation). The simple optical design of the LET eyepiece also fails to correct for edge-of-field astigmatism at the 150PDS’ fast f/5 focal ratio, and combined with the coma inherent at f/5 half the field will be swamped with blurry stars.
A 6×30 finder scope is also provided for aiming and aligning the 150PDS and its mount – with a 7-degree true field of view and crosshairs, it is pretty simple to use, though the upside-down view can be confusing and it’s hardly the most comfortable option.
The EQ5 Pro Mount
The Sky-Watcher EQ5 Pro mount is essentially a predecessor to the newer HEQ5 Pro mount also sold by Sky-Watcher, and a markedly better design than the Celestron Advanced VX thanks to its use of stepper motors versus the VX’s inferior servo motor drives. The EQ5 Pro mechanically shares similarities with the old Celestron CG-5 and Vixen Super/Great Polaris mounts, with mostly external motor hardware and a control box attached to the basic EQ5 mount. You operate it via the provided SynScan hand paddle or with a WiFi adapter (sold separately). For visual use, the EQ5 Pro is just as sturdy and convenient as the HEQ5 (though the counterweight shaft doe snot retract into the body when not in use) but for astrophotography this mount is not quite as good as the HEQ5 Pro; though it does use stepper motors like the HEQ5, it just isn’t quite as accurate or well-designed. You do get a polar scope and features like backlash compensation, but all in all, if you want to image deep-sky objects, we’d recommend the HEQ5 Pro instead, especially for a beefier imaging telescope like the 150PDS.
Getting started with astrophotography can be somewhat challenging. Often, individuals’ budgets necessitate a compromise on the mount, which can ultimately lead to disappointing results and the eventual sale of the mount in favour of an HEQ5 or NEQ6. Yes, you can get decent results with the EQ5 and 150PDS coupled to a good camera and inexpensive guiding setup, but achieving such results requires a great deal of effort, and the mount has literally half the precision of the HEQ5. If you absolutely cannot afford a better mount, the EQ5 Pro works, but you would be better served by the HEQ5 or NEQ6 – hence our 4-star rating of this package.
The EQ5 Pro’s 1.75” tripod legs and beefy head support a payload of around 9 kg for visual use or 6.5 kg for imaging – with the 150PDS optical tube weighing 5.5 kg without a camera, guiding or coma corrector, it’s pushing the limits of what this mount can handle for imaging. For visual use, the EQ5 Pro is rock solid; however an equatorial mount is unnecessary for this task and creates awkward eyepiece positions, a long setup time, and of course needless expense – get a Dobsonian (and preferably a larger aperture one) if you’re not interested in imaging. Sky-Watcher’s own Virtuoso GTi 150P shares the GoTo and optics of the 150PDS/EQ5 Pro at a fraction of the price, weight, or complexity.
Should I buy a Used Sky-Watcher Explorer 150PDS EQ5 Pro?
Considering the purchase of a second-hand Explorer 150PDS/EQ5 Pro could be a judicious choice, as the funds saved by buying pre-owned might be enough to acquire a guiding setup, all while still falling below the cost of a brand new HEQ5. Prior to purchase, ensure that the mount powers up, slews and tracks as it should, and does not exhibit significant corrosion. The optics within the Explorer 150PDS optical tube should be free of any corrosion or damage to the mirror coatings; the cost of recoating could easily exceed the price of a new optical tube assembly. Lost accessories or counterweights can be replaced inexpensively and without much difficulty, as can a lost SynScan hand controller. Sky-Watcher offers parts like adjustment/saddle knobs or the counterweight shaft as spare parts, and upgraded versions are available from ADM.
Alternative Recommendations
For those individuals whose interests lie particularly in the domain of deep-sky astrophotography, we would advocate the pairing of the 150PDS with the heavier duty HEQ5 Pro or NEQ6 equatorial mounts from Sky-Watcher instead if you can afford to do so. Alternatively, it might be worthwhile to explore our articles on the Best Equatorial Mounts and Best Optical Tubes. These resources will guide you in selecting an optical tube and mount combination that aligns most suitably with your personal preferences, the confines of your budget, the specifics of your camera, and the celestial objects you’re most keen on imaging. We’ve picked out some telescopes good for visual observation and/or light astrophotography in the list below:
Under £800 Range
- The StellaLyra 10″ f/5 Dobsonian flaunts a significantly larger 10” diameter primary mirror, delivering superior resolution and light-gathering capabilities compared to the 150PDS/EQ5 Pro. It also comes with a wide variety of accessories and features, while still maintaining a degree of portability. The 8” f/6 StellaLyra model is more affordable and includes the same high-quality features/accessories, but is roughly the same physical size.
- The Celestron StarSense Explorer 8″ Dobsonian brings to the table a larger primary mirror for bolder and brighter views than the 150PDS, and a degree of computerised pointing functionality, albeit devoid of motorised tracking, courtesy of its innovative StarSense Explorer technology. The telescope is practically designed with various knobs, handles, and cutouts incorporated, all of which greatly assist in its transportation.
- The Sky-Watcher Virtuoso GTi 150P shares the same optics as the 150PDS/EQ5 Pro but features a collapsible tube for enhanced portability. Its GoTo tabletop Dobsonian mount can be manually adjusted with ease and controlled via your smartphone or tablet. The manual Heritage 150P is identical in terms of its features, apart from its lack of electronics.
- The Sky-Watcher Skymax 127 AZ-GTi is a 127mm Maksutov-Cassegrain optical tube paired with the versatile AZ-GTi mount and tripod, a combination that incorporates motorised GoTo tracking abilities. The AZ-GTi is also uniquely designed to be manually adjustable by hand and is controlled via a smartphone, eliminating the need for a bulky hand controller. The Skymax 127 optical tube offers a level of performance that’s comparable to the 150PDS/EQ5 Pro when observing the Moon, planets, and other bright targets. This performance is achieved whilst also eliminating the need for collimation adjustments. However, it falls short for deep-sky viewing due to its narrower field of view and smaller aperture.
£800-£1200 Range
- The Celestron StarSense Explorer 10” Dobsonian delivers many of the same features that its 8” counterpart possesses, but with the added benefit of increased aperture and an easier collimation process. This results in a setup that is user-friendly, comparatively portable, and significantly more powerful than the 150PDS/EQ5 Pro.
- The Sky-Watcher Skyliner 200P FlexTube GoTo Dobsonian presents a greater aperture than the 150PDS/EQ5 Pro, and is equipped with a Dobsonian mount that facilitates both manual aiming and fully motorised GoTo/tracking that can be controlled via your smartphone or tablet. Its collapsible tube adds a touch more portability to its list of advantages.
- The Celestron NexStar 6SE offers a touch more in terms of planetary performance when compared to the 150PDS/EQ5 Pro, though a much narrower possible field of view which hinders deep-sky observation somewhat. It is a model that also excels in the areas of convenience and portability. The 6SE can be used for planetary imaging, light deep-sky astrophotography with an f/6.3 reducer, and presents the opportunity for an f/2 Hyperstar conversion, enabling super-fast exposures with 300mm focal length if it is remounted onto an equatorial mount.
Over £1200 Range
- The Celestron NexStar Evolution 8 employs Celestron’s C8 XLT optical tube, which provides superior light-gathering and resolution compared to a 6″ telescope, all whilst maintaining a compact form factor. The NexStar Evolution mount features fully motorised GoTo and tracking capabilities, in addition to an integrated lithium battery and WiFi adapter, which provides the convenience of controlling the telescope via your smartphone or tablet.
- The Sky-Watcher Explorer 200PDS NEQ6 Pro is an 8″ Newtonian reflector specifically engineered with astrophotography in mind, with the same mechanical design as the smaller 150PDS and mounted on the high-quality NEQ6 Pro mount. This pairing makes it an excellent choice for those in search of a ready-to-go imaging setup. The NEQ6 Pro mount surpasses the EQ5 Pro easily, with more accurate tracking/guiding and a heavier-duty design.
- The Sky-Watcher Skyliner 250P FlexTube GoTo Dobsonian incorporates a fully motorised GoTo and tracking system, which allows manual telescope aiming even when powered on, thanks to its FreedomFind encoder system. This model is more compact than a solid-tubed 10″ Dobsonian and offers the same performance advantages over the 150PDS/EQ5 Pro.
- 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
For a slightly higher magnification and a more optimised deep-sky viewing experience than that provided by the sole 28mm LET eyepiece supplied with the 150PDS, a 16mm UWA (41x) is an excellent option, whereas a 15mm redline/goldline (43x) serves as a solid budget-friendly alternative. For medium to high magnification, a 10mm UWA (65x) or a 9mm redline/goldline (72x) is ideal, while for higher magnification, a 4mm planetary eyepiece or 4mm UWA (163x) is a solid choice. A 3.2mm eyepiece (234x) delivers the highest practical magnification on most nights with this scope. Possessing a Cheshire collimation tool is also beneficial for maintaining precise collimation, ensuring the sharpest possible views with the 150PDS.
A significant issue to consider with any Newtonian for deep-sky astrophotography is coma. All Newtonians experience this to some extent, but at f/5, anyone using the 150PDS or its f/4 or f/5 counterparts will require a coma corrector for imaging; it’s practically a necessity. For visual observation, if you’re using a 2” wide-angle ocular, the coma is likely to become bothersome and a corrector will be desirable. The cost of these can vary. The Baader MPCC, Explore Scientific HRCC, and Tele-Vue Paracorr II are all good options.
If you intend to frequently observe deep-sky objects, the addition of a narrowband Ultra High Contrast (UHC)/OIII nebula filter to your 150PDS accessory collection is a wise move. It can significantly enhance your views of nebulae, such as the Orion Nebula, when used with almost any telescope, including the 150PDS. Additionally, this filter can be used with larger telescopes in the future, so it’s a worthwhile investment. It also offers sufficient contrast improvement to reveal the faint, ethereal Veil Nebula supernova remnant and other low surface brightness nebulae with the 150PDS, given adequately dark sky conditions.
Finally, you will require some form of DC power supply, like the Celestron PowerTank Lithium, to operate the EQ5 Pro mount unless you have access to a wall outlet. For astrophotography with the 150PDS/EQ5 Pro, you will need to select an autoguider, guide scope, camera, and likely a motor focuser such as the ZWO EAF as well.
What can you see?
The Sky-Watcher Explorer 150PDS is a versatile instrument, capable of photographing and delivering awe-inspiring views of nebulae and star clusters. Even under conditions of moderate light pollution, the telescope can reveal astounding details in brighter emission nebulae such as Orion (M42) and the Lagoon (M8). As one might anticipate, darker skies and the use of a UHC filter significantly enhance the viewing experience of these celestial objects, allowing for observation of fainter nebulae like the Veil, North America Nebula, and larger planetary nebulae such as the Dumbbell (M27) or the Helix Nebula. The 6-inch aperture also permits observation of the characteristic blue and green hues in smaller planetary nebulae like the Ring, Cat’s Eye, and Blue Snowball.
The Explorer 150PDS, particularly when equipped with a quality 2″ eyepiece and coma corrector, offers a wide field of view that makes it ideal for observing large open star clusters. Star clusters such as the Double Cluster in Cassiopeia, the Wild Ducks Cluster (M11) in Scutum, and the Pleiades (M45) in Taurus will come to life in the eyepiece of the 150PDS. The telescope’s brightest globular clusters, such as M13, M15, and M22, can be resolved into individual stars, though this will require higher magnifications (typically 80x or above).
Galaxies are also within the grasp of the Explorer 150PDS if you possess sufficiently dark skies; light-polluted conditions will tend to spoil the show and wash them out in any telescope, however. The 6-inch aperture gathers enough light to reveal dust lanes in larger, brighter galaxies like M31, M64, and M82. The spiral arms in galaxies like M51 and M101 might not be visible in great detail, but their presence is certainly noticeable. The Virgo Cluster presents another excellent target, with the Explorer 150PDS capable of displaying dozens of its member galaxies, with many individual galaxies fitting into the same low-power field of view.
The Explorer 150PDS performs admirably when it comes to lunar and planetary observation, although a high-quality short focal length eyepiece or Barlow lens will be necessary to achieve the optimal magnifications for planetary viewing. The telescope should easily resolve the phases of Mercury and Venus, along with an abundance of detail on the Moon. Mars’ polar ice cap and several dark markings become visible at high magnifications of 100x or more when Mars is at its closest to Earth. You can also resolve the disks of all four of Jupiter’s moons fairly easily with the 150PDS, in addition to their shadows during transits. Jupiter’s Great Red Spot, prominent equatorial belts, and many other cloud and atmospheric details are discernible. Saturn’s Cassini Division, its moons, and atmospheric details, as well as the disk of Uranus and Neptune’s moon Triton, are also within the scope’s reach. Pluto will require a larger telescope, 10 inches or greater in aperture, to spot even under ideal conditions, however.
Astrophotography
As previously mentioned, the Explorer 150PDS is an outstanding astrophotography telescope, and a properly guided and polar-aligned EQ5 Pro can provide decent results for imaging galaxies, star clusters, and smaller nebulae – albeit less consistently than a high-quality mount. On the other hand, planetary astrophotography can be easily conducted with the 150P by employing a 5x Barlow lens and an appropriate high-speed planetary video camera, which can also function as an autoguider for deep-sky imaging. While a 6-inch telescope may not be the optimal choice for planetary imaging, you can still obtain satisfactory results with proper collimation and precise focusing. If you are fortunate enough to experience favourable seeing conditions, the Moon, Jupiter, Saturn, and Mars will appear spectacular. Employing short exposures or high gain will also enable you to capture images of Mars’ tiny moons, as well as the dim and distant moons of Uranus and Neptune.
