The Optical Tube
The Celestron StarSense Explorer 150mm tabletop Dobsonian is a 6” (150mm) aperture Newtonian reflector with a focal ratio of f/5 and 750mm focal length.
I can see that the StarSense 150mm tabletop uses similar hardware and identical optics to many other 6” f/5 Newtonians offered by Celestron and their sister company, Sky-Watcher. This breaks from the convention of standard 6” freestanding Dobsonians, which often sport a focal ratio of f/8 and a focal length close to 1200mm.
The StarSense Explorer 150mm tabletop Dobsonian features a more compact f/5 focal ratio design with a focal length of 750mm. This results in a roughly 60% decrease in magnification and a correspondingly wider field of view with any given eyepiece, in comparison to its counterparts like the Sky-Watcher 6” f.8 Classic Dobsonian.
Despite the shorter tube, this fast focal ratio design also introduces the issue of coma. Also, when I use the inexpensive eyepieces, such as the one provided with the scope, it faces challenges in delivering sharp images across the entire field of view.
Collimation tolerances are more stringent as a result of the faster focal ratio of f/5.
The good news about collimation is that I don’t need a screwdriver to adjust this scope’s primary mirror (unlike its smaller 130mm StarSense Explorer counterpart). The secondary mirror is adjusted with a hex key, as is often the case on many mass-manufactured reflecting telescopes.
A 6” primary mirror, unlike that of a smaller aperture telescope, needs a non-negligible amount of time to cool down to ambient temperature and yield sharp images if brought straight outside on a chilly night. This is especially because the primary mirror in this scope uses plate glass, which is more drastically affected by temperature changes. However, I never had to wait more than 20 minutes, even if it was below freezing outside, for this telescope to provide the sharpest possible views. While I wait, I observe only at low power.
The StarSense Explorer 150mm Dobsonian uses a 1.25″ all-plastic rack-and-pinion focuser. This is the same cheaply made focuser used on many other telescopes I’ve used and reviewed. While functional, it wasn’t very precise for focusing at high magnifications. I also experienced wobbling and sagging with this focuser when under heavy accessory loads. Additionally, the 1.25” size format limits my maximum attainable field of view as well as prohibiting the use of a coma corrector.
Like the StarSense Explorer 130mm Dobsonian, the StarSense Explorer 150mm attaches to its tabletop Dobsonian mount with a pair of felt-lined metal hinged tube rings. The rings allow me to rotate the tube to place the eyepiece where I desire, as well as slide it forward/backward for balance. If you wish to use the optical tube on another mount, you could also unbolt the rings and attach them to a universal Vixen or Losmandy-style dovetail plate for use on most astronomical telescope mounts.
Accessories
The Celestron StarSense Explorer 150mm Dobsonian is accompanied by a set of two Kellner eyepieces along with a red dot finder.
Specifically, the eyepieces offered are a 25mm, providing 30x magnification, and a 10mm, which gives a magnification of 75x with this telescope. Constructed from metal and featuring optics coated with glass, these eyepieces, however, lack rubber eyecups. While they may exhibit minor issues such as chromatic aberration at the field’s edge and occasional glare, and the 10mm eyepiece might provide limited eye relief, they are generally functional enough to start out with. However, you’ll get significantly sharper views with aftermarket, higher-quality oculars, and 65x is hardly enough magnification for most lunar and planetary viewing, so you’ll want at least one additional shorter focal length eyepiece for 100x or more.
The same standard red dot finder Celestron provides with most of their entry-level telescopes is attached to the StarSense Explorer 150mm Dobsonian. It is more than sufficient for aiming this telescope even without the aid of the StarSense Explorer technology on account of this telescope’s short 750mm focal length and resultingly wide maximum field of view, which gives you plenty of margin for error.
Additionally, the Celestron StarSense Explorer 150mm Dobsonian is equipped with an eyepiece rack that can hold up to three eyepieces, attaching to the side of the mount. It should be noted, however, that this rack may not be suitable for wider-bodied eyepieces, which you’re likely to get your hands on soon after purchasing this telescope.
The Celestron StarSense Explorer 150mm Dobsonian also includes a collimation cap, which proves to be more than sufficient for accurate alignment of the scope’s optics; f/5 is more forgiving than a faster scope, which might require a Cheshire, while the plastic focuser will sag under the weight of a laser collimator, and thus one would deliver inaccurate results.
Mount
Emulating the mount design found in its smaller counterparts, the Celestron StarSense Explorer 150mm Dobsonian also utilizes the tabletop “Dobsonian” concept. Purists may argue that it’s more aptly described as a single-arm fork design, allowing the scope to pivot vertically on a single bolt and bushing, while horizontal (azimuth) movement is facilitated by Teflon pads in traditional Dobsonian fashion.
Incorporated in this design is a tension adjustment knob, essential for setting the desired friction to prevent the optical tube from undesired movement. Should you expand your accessory collection with new eyepieces, a Barlow lens, or other heavy items, adjustments to this knob might be necessary during observation to accommodate changes in weight and balance if you don’t feel like sliding the tube within the tube rings.
One potential drawback of the Celestron StarSense Explorer 150mm Dobsonian is the mount’s considerable size and the overall weight of the telescope. Despite its designation as a “tabletop” telescope, the scope doesn’t necessarily perform best on an actual table. For one thing, that might make it too tall, and stable enough tables are hard to come by. Recommended alternatives include a robust plastic bin (which might also serve as storage) or a milk crate, often favored for its convenience and portability. For children or adults observing from a seated position, these options typically provide sufficient elevation and stability.
Celestron’s StarSense Explorer Technology
The Celestron StarSense Explorer 150mm Dobsonian harnesses a technological approach that, while not revolutionary, has proven highly effective in astronomical applications: plate-solving. This method entails capturing an image of the night sky and then applying complex computer algorithms and celestial mapping to ascertain the telescope’s precise positioning. Traditionally, this technique is reserved for astrophotography to bypass the painstaking procedure of GoTo alignment and is often deployed to pinpoint individual celestial objects that may be themselves invisible through an eyepiece or with short exposures altogether.
The brilliance of the StarSense Explorer system lies in its ability to metamorphose your smartphone into a sophisticated navigational tool for your telescope. The architecture of the system demands the alignment of a diminutive mirror with the telescope mount, followed by leveraging your smartphone’s camera and computational prowess to perform plate-solving. Assembling the phone dock that accompanies the Celestron StarSense Explorer 150mm Dobsonian is refreshingly uncomplicated, and maneuvering the dedicated Celestron StarSense Explorer application is remarkably user-friendly. Upon completing a succinct alignment protocol, the app guides you in discovering thousands of galaxies, star clusters, nebulae, and other hard-to-find objects throughout the night sky.
This feat is accomplished through the app’s continuous tracking and depiction of your telescope’s orientation in real-time. It employs the camera and gyroscope information from your smartphone to execute this task. The accuracy is dependent on your smartphone but should be as good as about 0.25 degrees, equating to about half the breadth of the full moon. This is fine for locating most targets at low to medium power. The app will proclaim you are on target as soon as the object is within about ½ of a degree, however, which can make precisely locating smaller objects a little annoying, but it suffices for this wide-field telescope and all but the most demanding of users.
Celestron’s recent enhancements to the StarSense Explorer application, tailored specifically for their Dobsonian telescope series, include a vastly expanded database of deep-sky objects. This augmentation represents a significant leap forward from the prior version, which constrained the StarSense Explorer technology’s capabilities to merely locating the most luminous and conspicuous celestial targets. Work is also being done to integrate SkySafari Pro with the StarSense Explorer features, offering expanded features and an even larger database than the free app.
Should I buy a used Celestron StarSense Explorer 150mm Dobsonian?
In light of the StarSense Explorer 150mm Dobsonian’s recent introduction to the market, it’s hard to even find a used one, other than perhaps a returned/open box unit. Thus, encountering a used unit with damage to the base, tube, or deteriorated mirror coatings is an uncommon occurrence, likely to remain that way for years to come. However, caution must be exercised when considering the purchase of any reflecting telescope of this size with damage to the optical coatings, as the financial outlay required for recoating a small primary mirror typically surpasses the additional cost of simply obtaining a brand new instrument in the first place. Any damage to the base is likely irreparable due to the fragile chipboard construction, but a dented optical tube can be fixed.
Further scrutiny of a used StarSense Explorer Dobsonian is also required to ensure the inclusion of the StarSense phone dock, a crucial component that may have been detached for use with a third-party telescope by the previous owner. While Celestron is generally amenable to supplying supplementary unlock codes upon request, the absence of the physical hardware itself in second-hand units is not an infrequent situation.
Alternative Recommendations (USA)
The Celestron StarSense Explorer 150mm Dobsonian is hardly the most cost-effective pick in our price range. 6” and 5” GoTo or computer-aided telescopes are available at a lower cost, or you could just upgrade to an 8”. Most of our picks below will probably provide you with more excitement under the night sky and/or more bang for your buck.
Under $350
- The Sky-Watcher Heritage 150P uses the same optics as the StarSense Explorer 150mm, but with a collapsible tube and no StarSense Explorer technology. However, it is significantly cheaper, more compact, and includes slightly better eyepieces; you won’t regret getting one. The computerized Virtuoso GTi 150P (see below) is also an excellent option.
- The Sky-Watcher Heritage 130P is essentially a shrunken 150P, featuring a 5.1” (130mm) f/5 primary mirror but with the same collapsible tube, single-armed tabletop base, and identical accessories provided.
- The Zhumell Z130 is the same optically as the Heritage 130P, but uses a solid tube rather than a collapsible one. It also includes a slightly different accessory kit.
Under $550
- The Sky-Watcher Virtuoso GTi 150P, with fully motorized tracking and GoTo capabilities, offers a viewing experience identical to the Celestron StarSense Explorer 150mm Dobsonian. It also features a collapsible tube and comes with a pair of quality eyepieces. Its GoTo system can be operated via a smartphone or tablet, and a 130mm version is also available.
- The Orion SkyQuest XT6 provides brightness and resolving power on par with the Celestron StarSense Explorer 150mm Dobsonian but enjoys the benefits of an f/8 focal ratio, resulting in easier collimation and no coma, although at the cost of a reduced maximum field of view and a bulkier assembly.
- The Orion StarBlast 6 is nearly identical to the StarSense Explorer 150mm, with the notable improvement of a 2” rack-and-pinion focuser enabling the use of a coma corrector and 2” wide-angle eyepieces for a wider maximum field of view. As with the Virtuoso/Heritage 150P and StarSense 150mm, it is a 6” f/5 Newtonian reflector on a tabletop Dobsonian mount.
- The Celestron Astro Fi 130, a 130mm f/5 reflector with fully computerized GoTo capabilities, offers a larger field of view but slightly less light-gathering capability than the Celestron StarSense Explorer 150mm Dobsonian. It can’t be aimed manually but is effortlessly operated via a smartphone or tablet.
- The Celestron StarSense Explorer 130mm model (identical in design to the Zhumell Z130) provides analogous features and accessories to the 150mm variant, yet it comes with slightly less aperture at a correspondingly lower cost. While the views may be marginally less bright, it still packs a considerable punch in terms of capability.
$550-$800
- The Apertura AD8/Zhumell Z8/Orion SkyLine 8, with nearly double the light-gathering area and significantly more resolving power than the Celestron StarSense Explorer 150mm Dobsonian, offers features like a high-quality dual-speed Crayford focuser, built-in fan, right-angle finder scope, and included eyepieces.
- The Celestron StarSense Explorer 8” Dobsonian excels at the eyepiece like any good 8” Dobsonian, complete with a weight-optimized base and the proprietary StarSense Explorer technology for straightforward celestial navigation via a smartphone. Yet, it might lack some other features and accessories.
- The Orion SkyQuest XT8 serves as an economical alternative for those looking at 8” Dobsonians, presenting views as vivid and clear as the AD8 and similar models. However, it falls short in terms of additional features and accessories and is only slightly less expensive than its more well-equipped competitors.
Aftermarket Accessory Recommendations
The StarSense Explorer 150mm Dobsonian is nominally capable of handling up to 300x magnification, but typically you’ll find yourself using powers of 100–250x for globular clusters, double stars, and planets. A 6mm focal length “goldline” or “redline” ocular delivers 125x (or 250x with a 2x Barlow); we’d recommend it and a 4mm planetary eyepiece (188x) to start off with.
For those looking to enhance their viewing experience further, replacing the StarSense Explorer 150mm’s supplied 10mm Kellner eyepiece with a higher-quality eyepiece of similar focal length, such as the economical but high-performance 9mm redline or goldline ocular (85x), could be a wise choice. This eyepiece offers a sharper and wider view than the cheap 10mm Kellner, with longer and thus more comfortable eye relief compared to the Kellner design too. You might also consider adding medium–power oculars to the setup, such as an Agena 18mm Starguider, a Celestron 18mm Ultima Edge, and/or perhaps a 15mm redline/goldline to the mix. The specific focal lengths and designs for these can be chosen according to personal preference and requirements.
For low-power observation with the Celestron StarSense Explorer 150mm Dobsonian, eyepieces such as a 27mm BST Flat-Field (28x), 24mm Celestron Ultima Edge (31x), or a 24mm Explore Scientific 68-degree provide an ideal option for upgrading from the provided 25mm ocular. These eyepieces maximize the field available in a 1.25” format, and with this telescope will present a true field of view of a little over 2 degrees, equivalent to about four times the angular diameter of the moon in the sky. Compared to the stock 25mm Kellner eyepiece, any of these options offer a more immersive viewing experience with sharper stars across the entire field of view.
Utilizing a UHC, or Ultra-High Contrast, filter with the Celestron StarSense Explorer 150mm can greatly enhance the observation of emission nebulae by heightening their contrast against the night sky. Although not a complete replacement for observing under truly dark skies, this filter can still enrich the viewing experience, even in already dark conditions where the natural sky background isn’t completely black. The filter’s function of preserving and emphasizing the brightness of tiny planetary nebulae while simultaneously dimming the surrounding star fields at low magnification can bring subtle celestial details to life. It’s an optional addition that can take your astronomical exploration with the Celestron StarSense Explorer 150mm Dobsonian to a whole new level of clarity and enjoyment.
What can you see with Celestron StarSense Explorer 150mm tabletop Dobsonian?
The Celestron StarSense Explorer 150mm tabletop Dobsonian, with its 6-inch aperture, provides ample opportunity for skywatchers to explore an array of celestial objects. Thanks to its portability, taking it to locations with dark skies becomes a convenient task. Under such skies, viewing the moon and planets generally offers consistent quality, irrespective of the levels of light pollution, except when observing faint moons of outer planets. In those cases, local atmospheric turbulence or seeing conditions play a more significant role in obtaining clear images. However, to truly appreciate galaxies, nebulae, and star clusters, it would be advantageous to venture into areas where the Milky Way is at least faintly discernible to the naked eye.
One of the strengths of the StarSense Explorer 150mm Dobsonian lies in its ability to provide beautiful views of large open star clusters. Its wide field of view ensures that, whether under pristine or polluted skies, you can enjoy spectacular sights. Iconic objects like the Double Cluster in Cassiopeia, the Wild Ducks Cluster (M11) in Scutum, or the renowned Pleiades cluster (M45) in Taurus become accessible targets. The ability to resolve individual stars in the brightest globular clusters, such as M13, M15, and M22, adds to the telescope’s allure. Achieving such resolution typically requires magnification levels of 100x or more.
If you are fortunate enough to observe under dark skies, the Celestron StarSense Explorer 150mm Dobsonian extends its capabilities to include many thousands of galaxies. The dust lanes in prominent, brighter galaxies like M31, M64, and M82 become visible, and indications of spiral arms in galaxies like M51 and M101 can be discerned, even though the arms themselves might be just beyond the telescope’s grasp. Your exploration of the universe further deepens with the observation of the Virgo Cluster, where dozens of member galaxies are displayed, and various other, albeit dimmer, galaxy groups can be taken in as well if you observe them under a sufficiently dark sky with this telescope.
Nebulae, such as Orion (M42) and the Lagoon (M8), find their place in the Celestron StarSense Explorer 150mm Dobsonian’s repertoire, observable even under moderately light-polluted skies. However, the darker the sky at your observing location, the more vivid and detailed it appears. Utilizing a UHC filter can enhance the experience, unveiling otherwise elusive targets like the Veil, North America Nebula, or the Helix Nebula, which might be challenging to spot without the aid of a filter, even in dark conditions. Small planetary nebulae, including the Ring, Cat’s Eye, and Blue Snowball, further enrich the viewing experience; the 6” aperture even begins to reveal subtle blue and green colorations in some of these objects.
When it comes to our solar system, the Celestron StarSense Explorer 150mm Dobsonian has the capacity to provide insightful glimpses. During favorable conditions, you may observe the phases of Mercury, while Venus’s phases become readily apparent. The Moon’s surface comes to life with details such as thousands of craters, even those only a few miles across, in addition to features like cracks, ridges, fault lines, mountain ranges, and frozen lava flows. Mars offers views of its polar ice cap most of the time, and during its close approach to Earth, dark patches, dust storms, and even its tiny moons Phobos and Deimos might be within your grasp, although these dim and close-orbiting companions to the Red Planet are quite challenging to observe.
Jupiter, with its rich and colorful cloud bands, is a joy to observe through the Celestron StarSense Explorer 150mm Dobsonian. You can expect to see an assortment of festoons, storms, and cloud bands ranging in colors from blue, red, tan, pink, to gray and brown. The iconic Great Red Spot remains visible on a steady night at high power, even though it has been diminishing in size and often matches the color of the surrounding South Equatorial Belt. And of course, the four Galilean moons (Io, Europa, Ganymede, and Callisto) are discernible as tiny disks, along with their minute shadows as they transit Jupiter.
Saturn’s splendor is well-presented, with its rings and the Cassini Division becoming well-resolved at high magnification. You can also identify several cloud bands on Saturn and a gray-blue region near the poles. Several moons, including Titan, Rhea, Tethys, Dione, Enceladus, Mimas, and Iapetus, are visible, although Iapetus might be more challenging to spot when its darker-hued hemisphere faces us and correspondingly dims the icy moon.
The Celestron StarSense Explorer 150mm Dobsonian also resolves Uranus as a tiny greenish-blue dot, similar to the way William Herschel would’ve seen it with his own 6” telescope the night of its discovery. The moons of Uranus are likely too faint to see with only 6” of aperture, however, especially given the moderate amount of glare that the ice giant itself produces in its immediate vicinity. Neptune appears as a somewhat blurry bluish dot, often hard to distinguish from a star, but the StarSense Explorer app will allow you to confirm you’ve sighted it while its moon Triton is relatively easy to spot close by. Pluto is too faint to see with a 6” telescope; a 10” or preferably 12” is needed to reveal the distant, icy world.
Lastly, numerous asteroids such as Ceres and Vesta, along with thousands of dimmer and smaller others, are visible through the Celestron StarSense Explorer 150mm Dobsonian, and the app will guide you to their location easily. The brighter asteroids are easy to see even under heavily light-polluted skies. They’ll appear as gray or yellowish points of light, too small to resolve but still intriguing additions to the wide array of objects you can observe with this telescope.
