The 6SE Optical Tube
The 6SE’s optical tube is an orange version of the Celestron C6, which is a 6” f/10 Schmidt-Cassegrain. The C6 is the newest of Celestron’s standard SCT models, having been released as recently as 2006 (the other Celestron SCT models were devised in 1970, 1977, and 1993 for the C5/C8/C14, C11, and C9.25 respectively). The C6 offers significantly more light gathering ability and resolution than the C5, and is a favorite among experienced astronomers as a grab n’ go telescope.
Thanks to its small size, the C6 doesn’t really suffer from the mirror flop problems that plague larger Schmidt-Cassegrains nor a particularly narrow field of view. That being said, despite being physically compatible with a 2” diagonal, the C6 cannot actually illuminate the field of view of a 2” low-power eyepiece and will vignette quite badly with an f/6.3 reducer. Thus, the scope isn’t going to provide a field of view much larger than 1 degree (about 2 full Moons) – which means it isn’t ideal for wide-field vistas of star clusters and nebulae, though a 1-degree field is still plenty big to satisfy most users.
The C6 also has HyperStar compatibility. This means that with Starizona’s Hyperstar corrector, you can remove the secondary mirror, stick the Hyperstar in its place at the front of the telescope, and image with a CCD or CMOS camera at a focal ratio of f/2. However, the C6 only works with relatively small sensors in its Hyperstar configuration both due to the physical constraints of the design and the fact that a large camera housing can start to obstruct most of the telescope’s aperture. Additionally, a HyperStar costs more than the entire telescope, and is more useful if the C6 is mounted on a German equatorial mount than an alt-azimuth like the NexStar SE.
Being a Schmidt-Cassegrain, the C6 does need to be collimated from time to time. Contrary to what some folks might tell you, this is not a particularly scary or difficult process and absolutely does not require sending it back to Celestron! You simply adjust 3 small screws on the secondary mirror housing while pointed at a bright star – it’s arguably easier than collimating a Newtonian. Check out our collimation guide for more information. However, don’t buy the oft-advertised “Bob’s Knobs” or thumbscrew collimation knobs for the 6SE – they’re overpriced, and counterintuitively cause the telescope to go out of collimation more often due to the insufficient torque they exert to keep the secondary secured tightly.
The 6SE comes with a single eyepiece – a 25mm E-Lux Plossl providing 60x. It’s a good starter eyepiece for low magnification, but as with any telescope you’ll want at least a few extra eyepieces providing a range of magnification options. We’ll get back to this topic in the “Aftermarket Accessories” section.
Like most GoTo telescopes, the 6SE also comes with a simple red dot sight to complete the initial alignment before it can automatically slew itself around the sky.
Nexstar 6SE Mount Capabilities
The 6SE and 8SE both use a larger version of the NexStar SE mount with a tall, single-arm fork and a rather robust steel tripod with 1.75” legs. Unlike the smaller mount sold with the 4SE and 5SE, the 6/8SE mount does not come with a built-in wedge. The loss of this feature is not especially relevant, as it is little more than a useless gimmick on those telescopes.
The NexStar SE mount uses the same NexStar+ hand controller supplied with most of Celestron’s computerized telescopes. It looks pretty much like a pocket calculator. To use it, you enter in your location, time, and date, point the telescope at two or three reference stars and off you go. The whole process takes about 10 minutes from start to finish. Once the telescope is aligned you can choose from lists of deep-sky objects, the planets, and double stars to point it at, which it’ll slew to automatically with high accuracy assuming you’ve aligned it properly. However, getting the initial alignment to work can be challenging for some beginners, and the NexStar controller makes no indication of where in the sky your targets are or what is visible. Additionally, most of the objects available in its catalogs are too faint for the C6 to reveal, and its “40,000 objects” claim is mostly due to the fact that it features tens of thousands of SAO designated stars. You’re basically limited to the Solar System, the Messier catalog, and many of the brighter NGC objects.
Should I buy a Used NexStar 6SE?
If the price is right, go for it. Make sure that the telescope powers on and slews correctly, and that the interior of the telescope is clean.
The 6SE is just about the pinnacle of computerized (and indeed, non-Dob) telescopes under $1000, so if you’re looking for an alternative the only thing we’d recommend in its stead would probably be a Dobsonian. Here are some of the best options:
- Apertura AD10/Zhumell Z10/Orion SkyLine 10 – Triple the light gathering and just about double the resolution of the 6SE and with a significantly expanded kit of included accessories.
- Meade Lightbridge Plus 10” Triple the light gathering and just about double the resolution of the 6SE, and with a collapsible truss tube.
- Orion XT8i – Almost double the light gathering and 33% more resolution than the 6SE, with a computerized object locator and decent accessories included. Can also be used completely manually.
Aftermarket Accessory Recommendations
The 6SE really could use a few extra eyepieces. For starters, we’d recommend the beloved 6mm “goldline” for 250x, a fairly high but still reasonable magnification for the Moon, planets, and double stars. For moderate magnification, a 15mm goldline or 15mm Agena Starguider, either of which will provide 100x, is a good choice. Various other eyepieces at focal lengths in between these would also be good, but we’d recommend just two to start, along with of course the included 25mm Plossl.
The 6SE also benefits significantly from a dew shield. In addition to delaying the formation of dew/frost on your front corrector lens, the dew shield helps block stray light from entering the telescope tube and reducing contrast.
The last accessory we’d like to recommend is the Celestron SkyPortal Wi-Fi Module . It replaces the antiquated included hand controller by connecting the telescope to your smartphone or tablet, allowing you to align and control the 6SE with Celestron’s free SkyPortal app – or the vastly superior SkySafari app.
What can you see?
Within the Solar System, the 6SE can do a lot. Expect to see the following:
- Mercury & Venus – Phases
- The Moon – A ridiculous amount of detail, with features as small as a mile visible. We could go and write paragraphs about how great the views of the Moon are with the 6SE – or arguably any decent telescope – but we couldn’t possibly do it justice, so we’ll let the views speak for themselves.
- Mars – The ice caps are fairly obvious even when Mars is far from Earth. Around opposition you can see a bunch of dark shaded areas, which are just duller colored sand.
- Jupiter – The cloud bands and Great Red Spot look great. With good seeing you can pick out mottled details and ripples within the cloud bands and the brownish polar zones. Jupiter’s 4 large moons are especially obvious as disks when they eclipse and transit the planet.
- Saturn – Saturn’s rings are easily visible as is the Cassini Division in them, the latter provided you have good seeing. Around half a dozen moons can be spotted along with faint variations in the tones of Saturn’s cloud bands. Saturn’s largest moon, Titan, is visibly not a star and appears a slightly gold color.
- Uranus – A small turquoise dot. The moons are out of reach of anything under 10 inches in aperture.
- Neptune – A near-stellar blue dot. Its largest moon Triton can just barely be glimpsed under dark and steady skies.
Outside the Solar System, the 6SE is a solid performer, albeit limited somewhat by its aperture and field of view. You can expect to see a lot of open star clusters like M35, M11, and M67. Some large clusters like the Pleiades (M45) and Beehive (M44) cannot fit in the field of view with the 6SE, though they can still be enjoyed. The bright globular star clusters such as M13, M15, and M22 are kind of resolved with 6 inches of aperture – though barely, and only with fairly decent skies. Smaller globulars will remain fuzzy patches of light.
The few bright emission nebulae that dot our skies look magnificent in the 6SE, particularly if you use a good UHC nebula filter on them. The Trapezium star cluster’s fainter members nestled within the heart of the Orion Nebula are an easy catch. Planetary nebulae look decent with the 6SE, and some begin to show teal or blue coloration.
The 6SE’s aperture is enough to start showing you a fair amount of galaxies, but you won’t see detail unless you are under truly dark skies. With dark skies, however, galaxies start to come alive – M51’s spiral arms can be vaguely glimpsed as can the dust lanes in M82, M64, and M31. M33, M63, and M101 may also reveal faint spiral arms.
The 6SE is also a fantastic double star splitting scope, especially thanks to its lack of diffraction spikes from spider vanes that a Newtonian reflector typically suffers from. Sub-arcsecond doubles are possible with good seeing conditions.