Optical Tube Performance of Nexstar 5SE
The Celestron NexStar 5SE computerised telescope is based around the C5 optical tube, a telescope with 45 years of heritage that has even flown on Space Shuttle missions.
The C5 is a Schmidt-Cassegrain (SCT), which means that it does have a long focal length of 1250 mm, even though the physical length of the optical tube is short, as you can see in the above picture. The long focal ratio limits the telescope’s field of view somewhat, especially given that the scope comes with only 1.25″ eyepieces.
A 2” diagonal can, in fact, be attached to the 5SE if you want. But wide-field 2” eyepieces used with 2″ diagonals will vignette to the point that I don’t think it’s really worth the bother. The same was true when I tried using a dedicated f/6.3 focal reducer, an aftermarket accessory that is typically used to reduce an f/10 SCT to f/6.3 for astrophotography purposes. Unlike other Celestron SCTs, the C5 also lacks Fastar/Hyperstar capability, which are again popular aftermarket kits used for imaging purposes.
The Celestron NexStar 5SE’s 5” aperture is enough to show a fair amount of detail on the Moon and planets. But its large secondary mirror, which covers 38% of the diameter in the front, makes resolution and contrast much worse than with a 5″ Newtonian, Maksutov-Cassegrain, or refractor. It also reduces the light-gathering ability (already fairly small) by a fair amount.
As with most decent telescopes, the Celestron NexStar 5SE optical tube comes with a Vixen-style dovetail, which allows for easy, tool-free attachment and balancing on its mount, as well as numerous Celestron and third-party alt-azimuth and equatorial mounts that use Vixen saddles.
The 5SE does need to be collimated occasionally, as it is a Schmidt-Cassegrain.
Accessories: The Lone Plossl Eyepiece
The 5SE comes with a single 25mm 1.25” Plossl eyepiece, which provides 50x magnification, though you may want a 32mm Plossl and/or the aforementioned reducer-corrector for the widest field of view at low power.
The 5SE’s lone 25mm Plossl eyepiece really doesn’t allow us to get the most out of the telescope when it comes to high-resolution views of the Moon and planets. As such, I’d recommend a high-magnification eyepiece such as the 6mm “goldline” (208x).
For medium power, I’d use a 15mm goldline or a 15mm Agena Starguider for 83x.
Reviewing the Mount Features
The Celestron NexStar SE mount is an upgraded version of the original NexStar 5 mount, which was first released in the early 2000s.
It’s a simple alt-azimuth GoTo mount with a Vixen dovetail saddle that runs off fairly cheap servo motors.
The NexStar mount can point to over 40,000 objects in its database, the majority of which are simply stars and thus of little interest to the 5SE or any telescope. A good chunk of the deep-sky objects in its database are also unfortunately invisible with the Celestron NexStar 5SE telescope, on account of their meagre brightness or being in the wrong hemisphere of the sky to be seen from your location.
While this whole design works, I’ve come across a few issues that are worth sharing with you:
- The hand controller’s small buttons make it all too easy for me to push the wrong one because I have fairly large fingers and/or simply because I have my gloves on.
- It also consumes batteries very quickly. I always need a 12-volt power supply to use this scope peacefully.
- The SE mount is pretty steady, but it can still be bumped. If this happens, I have to re-boot and realign the mount.
- Lastly, I have to enter the time and date every time I start up the mount, unless I use Celestron’s SkySync GPS accessory or their SkyPortal WiFi adaptor with the scope. Both of these cost more than £150 each, if you want to buy one.
The SkyPortal WiFi adaptor, if you buy one, also mitigates the annoyance and limitations of the scope’s traditional hand controller by allowing us to control the scope with our phone. But that’s again at the expense of drawing significantly more electrical power from our scope/battery as well as eating up our phone’s battery charge.
The Celestron NexStar 5SE comes with a built-in equatorial wedge, so in theory, one can polar align it and do long-exposure astrophotography. However, the wedge has no fine adjustments and cannot be adjusted in azimuth, so it is basically useless. Also, the low-precision gears on the mount and the long focal length of the 5SE make it a bad choice for long-exposure astrophotography.
Should You buy a Used NexStar 5SE?
A used Celestron NexStar 5SE is a decent scope.
Keep in mind that you will still have to buy additional eyepieces to get the most out of the 5SE unless the seller is nice enough to throw some in.
Alternative Recommendations
Under £800
- The StellaLyra 10″ f/5 Dobsonian offers twice the resolution and over quadruple the light-gathering capacity compared to the Celestron NexStar 5SE, due to its impressive 10″ primary mirror. Included with the telescope are a variety of accessories, such as a 2″ low-power, 30mm focal length wide-angle eyepiece, a 9×50 finder scope, and a 9mm high-power Plossl eyepiece. The Dobsonian mount is simple to aim, quick to set up, and more stable than the 5SE’s computerised mount.
- The Celestron StarSense Explorer 8″ Dobsonian provides some computerised pointing capabilities, though no motorised tracking, with StarSense Explorer technology and, of course, possesses superior light gathering and resolving power to the 5SE with its 8″ aperture on a stable Dobsonian base. The telescope is easy to set up, transport, and use, though the number of accessories is limited compared to other options.
- The Sky-Watcher Virtuoso GTi 150P provides a 50% increase in light-gathering ability, superior optics, a wider field of view, and slightly higher resolution compared to the NexStar 5SE. With fully motorised tracking and GoTo technology, it features the FreedomFind encoder system to allow for manual aiming by hand too, regardless of whether the mount is powered on or aligned, and is controlled via your smartphone or tablet instead of a hand controller. Its collapsible tube ensures easy transportation, and its short focal length delivers a wide field of view, ideal for deep-sky observation. The Heritage 150P, a more budget-friendly alternative, is identical to the Virtuoso GTi 150P but lacks electronics.
- The Sky-Watcher Skymax 127 AZ-GTi combines the exceptional Skymax 127 Maksutov-Cassegrain optical tube with the versatile AZ-GTi mount and tripod, delivering motorised tracking GoTo functionality like the 5SE that can be operated through your smartphone, or simply pushed around the sky by hand thanks to its FreedomFind encoders. The Skymax 127 Virtuoso GTi offers the same features but is mounted on the Virtuoso GTi tabletop Dobsonian mount, with the possibility to connect it to a third-party tripod. The Skymax 127 optical tube beats the C5 XLT/5SE on the Moon, planets, and double stars and only suffers slightly worse performance when it comes to viewing deep-sky objects.
Over £800
- The Celestron StarSense Explorer 10″ Dobsonian delivers four times the light gathering ability and twice the resolving power of the NexStar 5SE, with Celestron’s StarSense Explorer technology providing an assist in aiming this telescope manually around the night sky. The base is fairly lightweight for a 10” Dobsonian and transportation is made easier with cutouts in the base and handles on the tube. Although this telescope comes with minimal accessories besides the StarSense Explorer technology, it offers great value in terms of aperture and portability for its price.
- The Celestron NexStar 6SE is similar to the 5SE in design and features, but its C6 XLT optical tube offers better light gathering and resolving power, a smaller secondary mirror obstruction, sharper images, and HyperStar compatibility on a steadier mount than the 5SE. Despite the minimal increase in weight, bulk, or price, the 6SE offers significantly more capability and value for your money than the 5SE.
- The Sky-Watcher Skyliner 250P FlexTube GoTo Dobsonian not only features twice the resolution, 4x the light-gathering power of the NexStar 5SE and of course full motorised tracking/GoTo, but also has Sky-Watcher’s FreedomFind encoder system to allow you to aim the telescope manually as you wish with no ill affect to the alignment or motors in the mount.
- The Celestron NexStar Evolution 6 is similar to the NexStar 6SE, sharing the C6 XLT optical tube, but offers various mechanical enhancements compared to the more affordable NexStar 6SE. It also includes a built-in Wi-Fi adaptor and lithium battery, making setup and use more straightforward.
Aftermarket Accessory Recommendations
The NexStar 5SE package comes with hardly any accessories besides its diagonal and lone 25mm Plossl eyepiece, making it essential to purchase several key upgrades and additional eyepieces to get the most out of this telescope. I highly recommend a dew shield for the 5SE, as with any catadioptric telescope, to minimise glare from nearby light sources entering the telescope, as well as to slow down frost or dew forming on the 5SE’s front corrector plate, and to keep pollen, dirt, and dust away.
A 1.25” 32mm Plossl eyepiece for 39x with the NexStar 5SE provides a slightly wider field of view and lower magnification than the provided 25mm Plossl, better for viewing deep-sky objects. A 2” star diagonal and eyepieces will vignette with the NexStar 5SE, as will any attempt to increase the field of view with an f/6.3 reducer and low-power eyepieces, so there’s little point in obtaining either. For medium magnification, I recommend a 1.25”, 16mm UWA (78x) or the more affordable 15mm redline/goldline (83x). For higher magnification, a 9mm redline or goldline (138x) eyepiece is ideal, while a 6mm redline or goldline (208x) provides the maximum useful magnification that the 5SE can be expected to deliver.
A UHC (ultra high contrast) nebula filter can substantially improve views of many nebulae, such as the Orion Nebula, when used with the NexStar 5SE, especially under light-polluted conditions. It’s best to use with your lowest-power eyepiece like the provided 25mm Plossl or preferably an aftermarket 32mm unit for even lower magnification. While it’s not a miracle cure for light pollution and is only effective for nebulae, it is helpful for improving your views of them nonetheless. The C5 XLT’s long focal length and resultingly limited field of view further restrict your target selection compared to a faster f/ratio Dobsonian of similar aperture to the 5SE, but a UHC filter is undoubtedly a useful asset for your astronomy equipment collection.
Finally, you’ll want a power supply such as the Celestron PowerTank Lithium or a Talentcell power pack to avoid exhausting too many disposable batteries with the 5SE and to avoid the chaos of dealing with an extension cord. If desired, the 5SE can also be controlled over WiFi with the Celestron SkyPortal app or SkySafari Pro using the SkyPortal WiFi adaptor, emulating the Astro Fi and NexStar Evolution telescopes but with a sturdier mount than the former and a much lower price tag than the latter.
What can you see with the Celestron NexStar 5SE?
The 5SE’s small aperture and narrow field of view make it primarily a lunar, planetary, and double star instrument.
- It shows us lunar craters and mountains just a few miles wide, the phases of Venus and Mercury, the cloud belts of Jupiter and Saturn, Jupiter’s Great Red Spot and the Cassini Division in Saturn’s rings, and the two gas giants’ various moons. I could also see Uranus and Neptune as bluish, star-like dots.
- Under clear and steady skies, the NexStar 5SE also has no trouble splitting double stars as close as an arc second apart.
As for deep-sky objects, the Celestron NexStar 5SE’s small aperture is the biggest limiting factor, even under dark skies.
- I could spot most of the objects in the Messier catalogue and view globular clusters and galaxies, but resolving individual stars in globular clusters as well as details in most galaxies, such as spiral arms or dust lanes, was challenging, even when I’m under dark skies far from light pollution.
- From the suburbs, the 5SE disappoints in all but the brightest nebulae and star clusters, such as M42, M27, and M13.
