The C6N Optical Tube
The Celestron Advanced VX 6″ Newtonian’s optical tube assembly is a 6” (150mm) f/5 Newtonian reflector, which has a focal length of 750mm. This is similar in specs to many imaging Newtonian astrographs out there, along with 6” f/5 tabletop Dobsonians. As is typical for these scopes, the optics in the Advanced VX 6” Newtonian are quite good, and at f/5, coma is barely visible at the edges of the field of a 1.25” eyepiece, though cheaper wide-angle eyepieces will have other aberrations at low powers away from the center of the field.
The Celestron Advanced VX 6” Newtonian uses a simple 1.25” rack-and-pinion focuser (albeit one made of metal and not plastic, at the very least). For visual use, a 1.25” focuser limits the achievable field of view. For astrophotography, a single-speed, cheaply-made rack-and-pinion focuser is insufficient to hold a heavy camera, and the 1.25” diameter prevents the use of a coma corrector to achieve sharp stars across the field of view as well as causing vignetting with larger camera sensors. You can retrofit a new focuser onto the C6N, but such an upgrade can easily cost several hundred dollars, and for imaging use, this induces worries about correct positioning and tilt if you do the installation yourself. The 1.25” adapter on the focuser unscrews to reveal standard T-threads to attach a DSLR or mirrorless camera, but as we mentioned, this is not ideal due to the focuser being prone to sagging or slipping out of focus under a heavy load and lacking any fine adjustment capabilities.
Collimation of the C6N optical tube is achieved through the use of three collimation screws on the back of the primary mirror cell and three hex screws on the secondary mirror holder, allowing you to adjust the alignment of the mirrors as needed. You’ll need a collimation tool, sold separately, to accurately collimate the C6N, since one is not included with the telescope by default.
The C6N attaches to the Advanced VX mount with a pair of tube rings, which allow for rotation of the tube as well as sliding it for balance, bolted to a Vixen-style dovetail plate that can be interchanged onto a variety of different equatorial and alt-azimuth mounts.
Like most Celestron computerized telescopes, the Advanced VX 6” Newtonian includes only one eyepiece, a 25mm Plossl providing 30x with the C6N optical tube and with a roughly 52-degree apparent field of view, which translates to a true field of 1.75 degrees across in the sky, or 5.5 times the angular diameter of the full Moon. While the 25mm Plossl does not max out the true field of the C6N, it is pretty close and is a decent ocular for low-power views of deep-sky objects. Additional eyepieces are necessary for higher magnifications.
The only other accessory provided with the Advanced VX 6” Newtonian is a 6×30 finder scope, which shows stars a couple of magnitudes fainter than the unaided eye and has an upside-down 7-degree field of view (similar to 7×50 binoculars) and crosshairs. It is adequate for the task .
The Advanced VX Equatorial Mount
The Advanced VX mount is Celestron’s low-cost GoTo computerized German equatorial mount. It is priced lower than competitors with a higher weight capacity, but makes compromises in its quality in order to achieve this. The biggest of these compromises is the use of cheap servo motors in the Advanced VX. Servo motors provide less precise tracking and guiding capabilities than stepper motors found in most other mounts, which can be problematic for deep-sky imaging. The Sky-Watcher HEQ5 Pro, EQ6R Pro, and various mounts from iOptron are vastly superior for deep-sky astrophotography purposes compared to the Advanced VX.
The other mechanical and technical aspects of the Advanced VX mount are also noticeably inferior to more expensive designs; the declination shaft is improperly supported by its bearing, and the mount saddle accepts Vixen and CGE-style dovetail plates but is a hair too narrow to support a true Losmandy D-style plate (millimeters wider than the CGE design) and grips dovetails with a simple pair of screws that dig into the metal and do not provide as secure a grip as a clamping design. Interfacing with the Advanced VX via a PC can be done with ASCOM drivers, but the mount requires you to use a MicroUSB cable and connect via the hand controller, rather than directly to the mount with a cable. This means that the Advanced VX also does not support EQMOD software and requires you to autoguide through its own ST-4 port rather than via a PC connection due to its lack of software support. Celestron also neglects to include a polar scope for polar aligning the mount by default in order to keep the retail price as low as possible.
In spite of its flaws, the Advanced VX can still work fairly well if you take its limitations into account. The 6” f/5 C6N optical tube is a fairly hefty payload for the Advanced VX to handle, at about 12 lbs bare, rising to 15 lbs with a camera and guiding equipment attached. However, if you don’t take overly long exposures and can achieve a good polar alignment, you should be fine.
Apart from the additional steps of balancing and polar alignment, the Advanced VX handles a lot like Celestron’s cheaper alt-azimuth GoTo mounts, using the same NexStar+ hand controller should you not elect to operate it through your PC. The C6N attaches to the dovetail saddle and balances with a single 11 lb counterweight, though barely, so you’ll need an additional weight or counterweight shaft extension for imaging purposes. Polar alignment can be accomplished with Celestron’s All-Star Polar Align, a polar scope, or a tool such as the PoleMaster.
Once polar alignment is complete, you simply go through a 3-star alignment, and the Advanced VX will then automatically slew to and track anything in its 40,000 object database. Features such as a sync tool and PPEC are available to improve tracking and GoTo accuracy for visual use throughout an observation session if inaccuracies build up.
The Advanced VX accepts Celestron accessories such as the SkySync GPS, SkyPortal WiFi adapter, and StarSense AutoAlign. It runs off DC power with the supplied power cord, but an AC adapter is available separately.
Should I buy a Used Celestron Advanced VX 6″ Newtonian?
A used Celestron Advanced VX 6” Newtonian telescope may be worth purchasing, as the money saved by buying used may be sufficient to purchase a better focuser for the telescope’s optical tube as well as other accessories. Be sure that the mount powers up, slews, and tracks correctly, and is not significantly corroded. The optics in the C6N optical tube should be free of corrosion and other damage to the coating; recoating them can cost more than simply buying a new optical tube assembly. Missing accessories or counterweights can be easily and cheaply replaced, as can a missing NexStar+ hand controller. Parts like adjustment/saddle knobs or the counterweight shaft are also available as spare parts from Celestron or in upgraded formats from ADM.
For deep-sky astrophotography purposes, we recommend looking at our Best Equatorial Mounts and Best Optical Tubes to pick out a suitable optical tube and mount pairing that is right for your budget, camera, and imaging interests in lieu of the Advanced VX 6” Newtonian. For visual observation, here are some of our top picks.
- The Apertura AD10/Zhumell Z10/Orion SkyLine 10 offers a significantly larger primary mirror delivering far better resolution and light gathering capability compared to the Advanced VX 6” Newtonian, and comes with a wide variety of accessories and features while still remaining portable.
- The Explore Scientific 10” Hybrid Dobsonian offers a similar performance boost to the AD10/Z10 over the Advanced VX 6” Newtonian but in a more compact package. However, the included accessories are not very good, and the focuser is only a single-speed design vs. the AD10’s dual-speed unit. The more expensive 10” Truss Tube model has a dual-speed focuser but still lacks decent accessories.
- The Celestron StarSense Explorer 8” Dobsonian has plenty of aperture and is aided by the Celestron StarSense Explorer technology to help you aim, with various knobs, handles, and cutouts installed to aid in carrying the telescope around.
- The Sky-Watcher Virtuoso GTi 150P has the same optics as the Advanced VX 6” Newtonian’s C6N optical tube but features a collapsible tube for greater portability and a GoTo tabletop Dobsonian mount which can be freely aimed manually and controlled via your smartphone/tablet. The manual Heritage 150P is identical, apart from its lack of electronics; a 130mm Heritage and 130mm Virtuoso GTi model are also available at lower prices than their 150mm counterparts.
- The Apertura AD12/Zhumell Z12/Orion SkyLine 12 has a primary mirror double the size of the tiny Advanced VX 6” Newtonian with a result of 4 times the light-gathering power and double the resolution. It also comes with a variety of accessories and a sturdy, easy-to-use Dobsonian mount.
- The Celestron StarSense Explorer 10” Dobsonian offers many of the same features and essentially the same form factor as the 8” model but with additional aperture and easier collimation, making for an easy-to-use and fairly portable setup with far more power than the Advanced VX 6” Newtonian.
- The Celestron NexStar 6SE offers slightly superior planetary performance to the Advanced VX 6” Newtonian but in a far more convenient and portable package, with additional options such as an f/2 Hyperstar conversion capability if mounted on an equatorial mount.
- The Sky-Watcher 8” FlexTube GoTo has more aperture than the Advanced VX 6” Newtonian with a much simpler Dobsonian mount which can be aimed manually as well as have its fully motorized GoTo/tracking controlled by your smartphone or tablet. The collapsible tube slightly enhances portability, too.
- The Sky-Watcher 12” Flextube Collapsible Dobsonian offers similar capabilities to the AD12/Z12 but in a collapsible tube for greater portability, with slightly downgraded but acceptable included accessories. A GoTo version is also available.
- The Explore Scientific 12″ Truss Tube Dobsonian is even more compact than the Sky-Watcher FlexTube scopes, and has a superior design to its mount. However, it’s quite expensive and you’ll have to shop for accessories to even use it, as it lacks stuff like acceptable eyepieces out of the box.
- The Sky-Watcher 10” GoTo Collapsible Dobsonian has a full motorized GoTo and tracking system which can also allow you to manually aim the telescope even when powered on thanks to its FreedomFind encoder system. It is more compact than a solid-tubed 10” Dobsonian and features the same performance gains as any other over the Advanced VX 6” Newtonian.
- The Celestron NexStar Evolution 6 offers various mechanical improvements over the cheaper NexStar 6SE, along with a built-in WiFi adapter, and the Evolution 8 adds additional aperture to the mix.
Aftermarket Accessory Recommendations
The provided 25mm Plossl eyepiece included with the Advanced VX 6” Newtonian is decent and is nearing the low-power limit of what the C6N can handle without the exit pupil becoming larger than the pupil in your eye. The Explore Scientific 26mm 62-degree (29x) provides a wider true field of 2.15 degrees with the C6N but is quite expensive, and upgrading your collection to include additional eyepieces is more important.
A medium-power eyepiece between 14-18mm focal length, such as the Explore Scientific 14mm 82-degree (54x) or 15mm SWA (50x) is ideal for viewing many smaller deep-sky targets along with the Moon, while a high-power eyepiece in the 6-12mm range such as the Explore Scientific 8.5mm 82-degree (88x) or 9mm redline/goldline (83x) boosts magnification further for planets, globular clusters, and double stars. The C6N can handle up to around 275x magnification, so a very short focal length eyepiece, such as a 3.2mm planetary (234x), Explore Scientific 3mm 52-degree (250x) or 4.5mm 52-degree (167x) is ideal for viewing the planets and splitting the tightest double stars. A 2x Barlow lens coupled to a 6-12mm eyepiece also works in lieu of a very high-power ocular and can be used for planetary imaging as well.
A 1.25” UHC nebula filter screws onto your eyepieces and enhances contrast on nebulae. The Orion UltraBlock 1.25” filter is our top pick for a UHC filter.
For imaging purposes, the C6N optical tube will require a T-ring to attach to a DSLR camera; a dedicated CMOS camera can just insert into the focuser. If you are willing to do some DIY upgrades, installing a 2” focuser such as the GSO 2” dual-speed Crayford would allow more versatility in camera attachment as well as the use of a coma corrector such as the Baader MPCC. You will also need a guide camera and guide scope for guiding the Advanced VX mount.
The Advanced VX mount is in need of some attention, too. A polar scope or PoleMaster/adapter will be needed for accurate polar alignment, and you’ll need either an AC power cord or some sort of power supply to run the mount. A Celestron PowerTank Lithium or generic Talentcell battery is enough for visual observers; astrophotographers will benefit from a heavier duty power supply like the Celestron PowerTank Lithium Pro or Westinghouse AC power supply.
What can you see?
The Celestron Advanced VX 6″ Newtonian is capable of both photographing and delivering breathtaking views of nebulae and star clusters. Under moderately light-polluted conditions, the scope can easily reveal stunning details in the brighter emission nebulae such as Orion (M42) and the Lagoon (M8). As you might expect, darker skies and the use of a UHC filter enhance your viewing experience on these objects, and allow you to see fainter nebulae like the Veil, North America Nebula, and the larger planetary nebulae such as the Dumbbell (M27) or the Helix Nebula. 6″ aperture of also allows you to see the characteristic blue and green coloration in small planetary nebulae such as the Ring, Cat’s Eye, and Blue Snowball.
The wide field of view provided by the C6N means it excels at observing large open star clusters, thanks to its wide field of view. The Double Cluster in Cassiopeia, the Wild Ducks Cluster (M11) in Scutum, and the Pleiades (M45) in Taurus are just a few examples of the many clusters that will appear vividly in the C6N’s eyepiece. The brightest globular clusters, such as M13, M15, and M22, can be resolved into individual stars with the C6N, although you will need to use higher magnifications (typically 80x or above) to do so.
Galaxies are also within the C6N’s reach, with 6” of aperture providing enough light-gathering ability to see dust lanes in larger, brighter galaxies like M31, M64, and M82. The spiral arms in galaxies like M51 and M101 are not visible in any kind of detail, but their presence is detectable. The Virgo Cluster is another great target, with the C6N able to show you dozens of its member galaxies, with many individual galaxies fitting into the same low-power field of view.
The C6N does a good job on the Moon and planets as well, though you’ll need a good short focal length eyepiece or Barlow lens to get up to optimal magnifications for viewing the planets. You should have no trouble resolving the phases of Mercury and Venus, along with a wealth of detail on the Moon. Mars’ polar ice cap and a few dark markings are visible at high magnifications of 100x or more when the planet is at its closest to Earth, and you can resolve the disks of all four moons of Jupiter fairly easily, along with their shadows during transits. Jupiter shows the Great Red Spot, its prominent equatorial belts, and many other cloud and atmospheric details. You’ll also be able to resolve the Cassini Division in Saturn’s rings and the planet’s own moons and atmospheric details, the disk of Uranus, and Neptune’s moon Triton. Resolving Neptune clearly, as well as seeing the moons of Uranus or fainter Pluto, will require a larger telescope.
The Celestron Advanced VX 6” Newtonian telescope is, of course, not ideal for deep-sky astrophotography due to its 1.25”-only focuser, which limits what cameras you can use with it and inhibits the installation of a coma corrector. However, with a DSLR/mirrorless APS-C sized or similar small sensor, you can get great deep-sky images of smaller targets where coma can be cropped out, provided you don’t push exposures too long, as this can cause blurred/trailed stars thanks to the limitations of the Advanced VX mount.
Planetary astrophotography with the C6N can be accomplished with the use of a 5x Barlow lens and a suitable high-speed planetary video camera. A 6” telescope is a little on the small side for planetary imaging, but you can still get decent results with good collimation and precision focusing. The Moon, Jupiter, Saturn, and Mars will look excellent if you are fortunate enough to have decent seeing conditions. You can also use the scope with a solar filter to show sunspots, as well as resolve the phases of otherwise detail-less Venus and Mercury. Using short exposures or high gain can also allow you to image the tiny moons of Mars or the faint and distant moons of Uranus and Neptune.