Several years ago, I took over responsibility for managing my club’s Loaner Telescope program. We had a fairly rag-tag fleet of telescopes, everything from an 80mm short-tube refractor to 14.5-inch truss Dobsonian. At the time I took over, we had two NexStar SE scopes, a 5SE and a 6SE. During my tenure, we accepted donations of another 5SE and a 4SE.
The NexStar line began in the late 1990s, mostly as a response to some of the LX products that Meade was turning out. Designed to be a low-cost, easy to use GoTo telescope, the early NexStar line gained a strong following.
But all was not well for Celestron, which was struggling to keep their financial heads above water. This finally led to the company being bought by the SW Technology Corporation, a Delaware-based affiliate of the Synta Technology Corporation of Taiwan, which had been manufacturing many of Celestron’s products for some time. At this point, Celestron became just another brand in the Synta lineup, which includes Sky Watcher and Tasco as well as equipment sold by other independent brands such as Orion.
In the years since their acquisition, Celestron’s product line has morphed, with a portion of their equipment being marketed to beginners and casual users, and other products marketed toward serious amateurs. Unfortunately, this also shows in their quality.
Today’s NexStar Line
The NexStar product line today is actually three separate lines of products. The NexStar SLT line, which they describe as “Designed to be an affordable entry level to mid-level computerized GoTo telescope,” constitutes their lower-end tier and includes Newtonian, Refractor, and Maksutov-Cassegrain optical tubes on their NexStar SE mount.
The NexStar SE line includes a 4-inch Maksutov and 5, 6, and 8-inch Schmidt-Cassegrain optical tubes, all painted Celestron Orange as an homage to the legendary Orange Tube C8 that made the company’s name in the 1970s. These all appear to be targeted at amateurs looking for an easy-to-use GoTo system that doesn’t cut corners on the optical capabilities.
The upper-tier is the NexStar Evolution line, which raises the bar on the line. With improved mechanics, including brass gears, a built-in rechargeable battery, and added features such as WiFi, it comes in 6, 8, and 9.25-inch versions.
The NexStar 6SE Overview
The 6SE is arguably the most popular of the line. It comes with Celestron’s popular 6-inch Schmidt Cassegrain Telescope, which has an actual aperture of 150 mm and focal length of 1,500 mm, giving it a focal ratio of f/10, which is typical of most SCTs. The OTA comes on a Vixen-style dovetail bar, which fits into the dovetail saddle on the mount.
The mount is altitude-azimuth single-arm fork-style mount with a total instrument payload capacity of 12 lbs. The OTA’s weight is 8 lbs., which offers plenty of room for a finder, visual back, diagonal, and eyepiece. It comes with a 1.25” Diagonal and 25 mm eyepiece and Celestron’s Star Pointer, which is a zero-power red-dot-style finder.
The mount for the 6SE weighs in at only 11 lbs. and comes with a tripod with 2” stainless steel legs which weigh in at 9lbs. The total package, then, comes in at under 40 lbs. and can be broken down into very manageable components. This makes it convenient for transport or for people who don’t want to haul a large scope up and down the stairs of an apartment building.
The mount is compatible with the latest generations of Celestron’s NexStar hand control, which contains over 40,000 objects in its database, along with the ability for users to define up to 200 of their own objects. The NexStar system offers five different alignment options from the user-friendly Sky Align system to one-star and two-star alignments and even a quick-alignment which uses the previous alignment data.
The overall package is designed to offer good optical performance with good GoTo and tracking performance. This, coupled with a lightweight and compact form-factor and ease of setup, make a strong combination for the casual to a moderate observer.
Celestron has long turned out some of the best optics in its price class. Their SCTs set the standards for the SCT back in the ’60s and ’70s. Like any manufacturer, they have had their ups and downs over the course of their history. Still, their SCTs are still hard to beat, and their current offerings are consistently good performers.
The 6-inch OTA provides a good balance between light gathering capability, magnification, size, weight, and cost. When matched up with a good eyepiece, it can offer excellent views of Mars, Jupiter, and Saturn, as well as the Moon, even under light polluted skies. Under fairly clear, dark skies, all of the objects in the Messier and Caldwell catalogs should be visible, as well as a good portion of the NGC catalog.
But there are a couple of disappointments here. First is the finder. In order to cut costs, many manufacturers have been providing low-cost (and quality!) zero-power finders. The Celestron Star Pointer sight is just not the right tool for the job with this scope. A 30mm or better optical finder would be a much better addition to this scope.
The other disappointment is found in the included eyepiece. The bundled 25mm eyepiece is among the lower-end eyepieces Celestron sells. Of course, most owners will want to purchase their own, better eyepieces, and bundled eyepieces are often more of an afterthought than anything meant for serious use. Still, Celestron could certainly stand to upgrade the eyepiece in the package. Their nearest competitor in this market segment, Meade, usually bundles one or two of their 4000 Series eyepieces with similar telescopes, which are a serious improvement.
The design concept of the NexStar SE mounts is very attractive. But the SE line doesn’t always live up to their promises. This appears to be more a problem with quality control and manufacturing than it is overall design. The Celestron engineers designed a competent mount, but the Suzhou Synta Optical Technology company of China – Synta’s manufacturing arm on the mainland – doesn’t seem to execute the design for these lower-middle range models as well as they do for their higher-priced models. As a result, they are somewhat prone to breakdowns.
When these mounts work, they’re really not too bad. The GoTo accuracy is fairly good for an alt-az mount, and it can usually put the desired object in the field of view (whether or not you can actually see it depends on the sky conditions and the object). Of course, the accuracy of the GoTo on this mount will be heavily influenced by how accurate your initial inputs are for time, date, and location as well as your star alignment points. All of these data points can throw off your accuracy. As with any alt-az GoTo mount, I recommend regular re-synching to maintain GoTo accuracy.
The Down Side
The problems with these mounts come when they don’t work as expected. This can be broken down into two separate concerns: electronics and mechanics.
The mechanics are generally functional, but they don’t always hold up to heavy use. Celestron’s listed weight capacity for the 6SE is 12 lbs. The OTA itself weighs 8. This leaves 4 lbs. for additional payloads such as diagonal, eyepiece, and finder. This is sufficient for casual use, but users who want to use higher end – and often heavier – eyepieces start pushing the limits. And those who attempt to add a camera can be pushing things right to the limits.
The same mount is used for the 8SE, and this is a real problem, as the 8SE itself weighs 12 lbs. Right off the bat, you’re overloading the mount just by adding an eyepiece. Of course, one would expect that the rated payload has a comfortable margin for error. But it’s still questionable to load the mount so much.
The key concern here is that the weight loading can put stress on the motors and gears, particularly in the altitude-azimuth. This can cause damage to the gears and other mechanical components, or even damage the motors.
For this reason, I would not recommend this scope for younger users who are more likely to handle the instrument roughly.
The larger problem with these mounts is found in the electronics. Again, as designed, the mount looks good. But under the hood, the quality of components and workmanship of the wiring and assembly leave something to be desired.
With all of the NexStar SE scopes I have encountered, the plug has fit loosely. The connector is a common IEC 60130-10 Type A coaxial connector. While you may not be familiar with that identifier, you’ve seen these plugs all over. The outer diameter of the plug is 5.5mm and the jack it plugs into has a center pin (which is the positive lead). The ones used by Celestron are usually threaded on the outside of the jack, and a built-in cap on the plug screws down onto the jack, holding the connection. In my experience, without this, the cable tends to be loose and has a habit of losing contact. Screwing down helps, but not always.
If the contact isn’t solid, this can really cause problems. It can cause the power to cycle off and on unexpectedly, which, of course, will cause you to lose your alignment and have to re-setup the mount. But worse still, a rapid off-on-off-on of the power here can damage internal components.
Even if the plug is solidly connected, the wiring isn’t always well done, resulting in loose connections and cold solder joins, which can experience the same kind of power fluctuation. One NexStar 6SE I’ve had experience with burned out two hand controllers before the problem was discovered.
Repairs to the mount can be expensive, often costing a significant portion of the original price. And let me be clear on this: if the mount stops working, either mechanically or electronically, there is no manual backup.
You could unlock the catches on both altitude and azimuth axes and manually move the mount. Moving the azimuth axis isn’t a problem. But the altitude axis is – the OTA will just flop around unless you hold it in position, and that just doesn’t really work well. So, if the mount breaks down until it’s fixed you have a fairly expensive conversation piece or closet filler.
To summarize this review, I find this scope and the rest of the NexStar SE line to be disappointing. They should be a lot better than they are. If quality control was a bit better on the line and the mount’s weight capacity was just a little higher, I’d be a lot more impressed with it. There’s nothing wrong with the optics, though better accessories would be nice.
I know some people have had great luck with their NexStar scopes. But I’ve just seen too many problems to outright recommend this. If you have one or get one cheap, then it can be a great option for quick setup and portable use.
Celestron has proven they can do better. The NexStar Evolution line is significantly better – as you would expect with the increased price.
If you can afford the Evolution, it’s the better buy. If not, you might consider a 6 or 8 inch Dob instead. If you do buy one of these, if a protection plan is offered, I’d strongly recommend it.
For all that, its nearest competitor, the Meade ETX-125, isn’t any better and might be a little less reliable. Between the two, I’d choose the Celestron.