While small GoTo telescopes aren’t particularly great for beginners interested in astronomy, Celestron’s NexStar 4SE is an okay-choice for those who must have GoTo.
But the scope is too small for the GoTo to be worth it, and the telescope makes a number of promises that fail to deliver.
This review will explain all you need to know before buying the 4SE.
The Celestron 4SE Optical Tube
The NexStar 4SE is a Maksutov-Cassegrain and shares much of the heritage of Celestron’s C90, of which the 4SE is basically a scaled-up version. The Maksutov-Cassegrain design uses a very fast spherical primary mirror with a meniscus corrector lens and an aluminized “spot” on the corrector serving as the secondary mirror.
The 4SE, like the C90, is of a variant called the Gregory-Maksutov, where the secondary is nothing more than an aluminized spot on the back of the corrector lens.
Maksutovs have small secondary mirrors, usually with great optics, and long focal lengths, which makes them great for lunar, planetary, and double-star viewing.
The auto-orientation feature makes you view the image right side up instead of the inverted view that is typical with Cassegrain telescopes.
The 4SE comes with a single 25 mm 1.25ʺ Plossl eyepiece, which is good for low power, though you may want a 32 mm Plossl for the widest field of view. Additional medium- and high-power eyepieces of shorter focal length would be good to get the most out of your 4SE.
The 4SE is rather small, and this and its long focal length of 102 mm means that this is more of a planetary telescope. You’re limited to the brightest deep-sky objects.
The NexStar catalog contains 40,000 objects. This is a mixed bag. You’d be lucky to be able to see more than a couple of hundred deep-sky objects even under dark skies, thanks to the 4SE’s small aperture.
There are no asteroids in the catalog, and the Sky Tour function often lists objects which are too dim for the 4SE or not in a convenient position for viewing.
The only use of such a large catalog is in using the massive stellar database to locate asteroids, which one does by finding a star in the same field of view of the said asteroid in a planetarium app then entering said star into the hand controller, and for locating variable and double stars.
Even then, the “40,000 objects” advertising is a gimmick.
Mount's Stability and Alignment Easiness
The 4SE mount is fairly steady, and the 4SE’s tube does have a Vixen dovetail, so it can be put on other mounts, but then it would be at an odd orientation. However, it is very much antiquated.
The hand controller’s small buttons are difficult to operate with gloves on, and one must enter the time and date every time you set the scope up (how hard would it have been to install an internal clock?), and this will very quickly consume battery power.
An external power supply is required. And don’t forget to put AA batteries in the mount for backup energy, because if the power supply’s connection cuts, for even half a second, the entire telescope will reboot, and you’ll need to enter in the time, date, and align the telescope all over again. It has to use eight AA batteries.
Also, changing location is quite complicated. The scope really needs to come bundled with Celestron’s SkySync GPS module for updating the time, date, and location, which costs over a hundred dollars. The SkyPortal WiFi app will also solve this issue and allow you to control the scope with your phone, but either option is expensive (and the latter really requires the SkySafari app which is another $20).
Aligning the 4SE is supposed to be a breeze with Celestron’s SkyAlign technology, which, in theory, allows one to point it at any of the three bright targets (even the Moon or planets) and be aligned in seconds.
However, after hundreds of ALIGNMENT FAILED messages that I’ve seen with every NexStar telescope I’ve ever used when trying to SkyAlign, I can say with confidence that SkyAlign is an absolute joke and never works. The Auto Two-Star method is accurate, but won’t let you select any star you want, and tends to force you to align to stars that aren’t the brightest, or may not have the most memorable names.
The 4SE would do well for lunar and planetary astrophotography, and maybe simple, shorter than thirty second exposures. But that’s going to be the limit.
The scope’s f/13 focal ratio is too slow for long exposures in order to capture anything, and the altazimuth-nature and miss accurateness of the mount will cause blurring anyway.
The built-in wedge is a gimmick, and it wouldn’t even matter if it works anyways because of the aforementioned issues.
What's The Bottom Line?
To summarize, if you really must have a small GoTo telescope, the Celestron NexStar 4SE certainly shines as one of the better examples. However, it is still far from perfect and I would definitely not buy another as my first scope.