The Celestron NexStar SE series of telescopes (4SE, 5SE, 6SE, and 8SE) has gained some attention among stargazers. While they might seem attractive to many, especially beginners lured by the promise of advanced features, we have some reservations. Here’s why the NexStar SE range isn’t on our recommended list:
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1. High Price Point
Compared to cost of other telescopes with similar capabilities, the Celestron NexStar SE series telescopes are considerably more expensive. And this elevated cost doesn’t necessarily translate to an equivalent increase in quality or functionality. The NexStar mounts are not particularly well-made, technologically advanced, or even that sturdy.
2. Manual Aiming Limitations
A significant drawback of these telescopes is that you can’t aim them manually. The azimuth axis of the NexStar SE mount cannot be moved without the motors, while attempting to adjust the altitude (up/down) pointing could damage the gearing and ruin the tracking and pointing accuracy of the mount. Just bumping the telescope at all, of course, also throws the alignment off until you reboot the mount and start all over.
This restriction can be a significant inconvenience for those who prefer a hands-on approach or in situations where the computerized system might malfunction. As mentioned, there are many computerized telescopes/mounts that do not suffer from this drawback and also feature the ability to connect to your smartphone for time and location information and even software compensation for a not-level tripod.
3. Lack of Capability
The Celestron Nexstar 4SE and 5SE models, despite their computerized mounts, don’t offer enough aperture or a wide enough field of view to enjoy more than a couple dozen deep-sky objects. Their computerized mounts are therefore little more than dead weight. Small catadioptrics are ideal for a quick peek at the Moon, planets, or bright objects like double stars, but they are of course far from convenient when bundled with a heavy computerized mount that takes 10-15 minutes to set up and will require you to start over if you bump it. You would be better served by getting a telescope of this size atop a manual mount for less money, or at least a computerized mount model that allows you to manually aim the telescope, preferably with built-in WiFi operability like the Sky-Watcher AZ-GTi or Virtuoso GTi telescopes.
4. Not Good for Astrophotography
While some may believe these telescopes are suitable for astrophotography due to their marketing and branding, this isn’t the case. For starters, the Celestron NexStar SE telescopes use alt-azimuth mounts. In astrophotography, particularly when capturing deep-sky objects over extended exposures, the orientation of the telescope needs to align with the rotation of the Earth. Alt-azimuth mounts, by their design, cannot track this celestial movement perfectly. The result is field rotation, where stars and other celestial objects appear to rotate around the frame’s center over time. This rotation can blur or distort images, especially during long exposures.
While it’s possible to counteract field rotation using a wedge, this solution presents its own challenges. A wedge tilts an alt-azimuth mount to convert it into an equatorial configuration, and the NexStar SE mounts do have software to allow for this. However, first, you need the wedge.
For the Celestron Nexstar 6SE and 8SE models, an aftermarket wedge can be quite pricey, while the built-in wedge on the 4SE and 5SE models is a complete joke. It does not have adjustments for side-to-side alignment with the celestial pole, and the tilt plate has no fine adjustments or any additional way to brace or lock it in place besides a lone thumb screw. In practice, it doesn’t add much value or functionality to the telescope. Polar alignment accuracy, even with a properly made wedge, can be quite difficult to achieve compared to a German equatorial mount, especially since computerized polar alignment tools now exist for these mounts.
In any case, the gearing inside the NexStar SE mounts is nowhere near as precisely made for deep-sky imaging. There is a port for an autoguider on the mount, but even with guiding, the tracking accuracy is not very good for long exposures.
Optically, while made to a high standard of quality and yielding razor-sharp images, these telescopes are all less than ideal for deep-sky astrophotography due to their chosen configurations. The NexStar 4SE’s long f/13.5 focal ratio means it requires extremely long exposure times to capture anything at all, and the telescope is completely incompatible with a focal reducer. Models like the 5SE, 6SE, and 8SE are Schmidt-Cassegrain Telescopes (SCTs). Typically, these SCTs have an f/ratio of f/10, which is still too “slow”. Capturing faint objects with such an f/ratio would require longer exposure times, increasing the chances of problems and generally being less efficient. Thus, many astrophotographers turn to aftermarket focal reducers, such as the popular f/6.3 reducer. These reducers effectively decrease the f/ratio, allowing for faster imaging. However, they come at an additional cost, and when factoring this into the already high price of the NexStar SE series, it’s another expense to consider. However, the 5SE will vignette severely with a reducer anyway.
While the 6SE and 8SE telescope optical tubes (sold alone as the C6 and C8 XLT, respectively) can be adapted for deep-sky astrophotography atop a different mount using the HyperStar system or an f/6.3 reducer, this isn’t a straightforward solution. To start with, these upgrades, along with a new mount, can be expensive. Moreover, even after investing in these upgrades, newcomers to astrophotography will find that there’s a steep learning curve.
The concerns that make the NexStar SE series less than optimal for long-exposure astrophotography are largely irrelevant when it comes to capturing the moon and planets. In fact, for planetary astrophotography, the NexStar SE telescopes are more than capable, though any telescope with motorized tracking will work for this task, and all that really matters is having a large aperture and good optics.
5. Stability Issues with the NexStar 8SE
The Celestron Nexstar 8SE, one of the larger models in the series, has an undersized tripod, which is a shock considering how high of a price point it retails for. A wobbly mount can be particularly frustrating, as it will affect the pointing/tracking accuracy of the 8SE’s mount and also make it harder to focus the telescope at high magnifications as the view bounces back and forth.
6. Its Narrow Field of View
Due to their long focal lengths, these telescopes have a narrower field of view (FOV). This characteristic limits the breadth of the sky you can observe at any given time, potentially missing out on wide-field celestial sights.