The Celestron 4SE Optical Tube
The NexStar 4SE is a Maksutov-Cassegrain telescope with an aperture of 4” (102mm) and a focal length of 1325mm, giving it a focal ratio of f/13.
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 most mass-manufactured Maksutovs today, 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.
Maksutov-Cassegrains, also referred to simply as Maks or Maksutovs, have small secondary mirrors, long focal ratios (typically f/12 to f/15), and the corrector lens and mirrors are very easy to make to high tolerances, making them provide stunning, sharp lunar and planetary views. Since the secondary mirror in a Gregory-Mak is simply an aluminized portion of the corrector plate, commercial Maksutovs almost never need collimation, and some don’t come with provisions to do it at all – though the 4SE has a few small collimation screws in the back that could be adjusted for collimation by an experienced user.
The 4SE also has an integrated “flip mirror” at the back, which means that there is a built-in star diagonal which can be retracted to allow light directly out of the back of the telescope and into a camera adapter, usually for a DSLR or mirrorless camera. However, this flip mirror simply adds some additional bulk and complexity to the telescope, requires an unusual threaded adapter to be utilized, and isn’t really necessary – a normal Maksutov gets by with the user just detaching the star diagonal, and the 4SE isn’t really intended for astrophotography anyways – especially not with a DSLR or mirrorless camera, which are primarily meant for long exposures.
Since it can only take 1.25” eyepieces, with its long focal length of 1325mm the 4SE is limited to a maximum field of view of around 1.2 degrees, or about 2.5 full Moons across – a rather small figure for a 4” telescope. A shorter and even slightly larger instrument such as the Orion StarBlast or Zhumell Z114 can get 3.6 degrees, while the very-slightly-smaller Zhumell Z100 or Orion SkyScanner can achieve a field of view of about 4 degrees across – triple and nearly quadruple that of the 4SE respectively (and they cost a fraction as much, to boot).
Price – $518.51
Of course, most of the advantage of that extra field of view is simply in finding objects manually, which the Nexstar 4SE does not need to worry about due to its fully computerized mount.
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However, a wide field of view is still desirable for many of the large star clusters, asterisms and nebulae that a small telescope excels at. Make no mistake – the 4SE is really a planetary telescope, and most deep-sky objects either don’t really fit in its field of view, or don’t look particularly impressive. And if all you’re looking at is the planets, the Moon, and perhaps a few double stars, how much do you really need GoTo anyways?
The 4SE comes with a single 25mm Plossl eyepiece, yielding 55x. This is good as a low-power or “finder” eyepiece for viewing deep-sky objects and initially aligning the telescope, but for optimal usage of the telescope you’ll want stuff for higher magnifications such as a 9mm or 6mm “goldline” or some other good eyepieces, and perhaps a 32mm Plossl for the widest field of view possible. The only other accessory included with the 4SE is its StarPointer red-dot finder, which is used for aligning the telescope’s GoTo system.
The NexStar 4SE Mount
The NexStar SE mount is similar in all versions, but the 4SE and 5SE have a shorter fork arm on the mount and a base with 3 foot-like bits sticking out, a holdover from the days of the NexStar 4GT, the 4SE’s predecessor which was sold as a tabletop telescope.
The mount is well-made. The gears in it are a bit better than the cheaper NexStar SLT scopes, but still have a lot of backlash – which is somewhat problematic when moving the telescope at high powers or attempting to shoot planetary images. The tripod legs are, however, solid steel, and the whole assembly is actually somewhat overkill for the 4SE’s tiny optical tube. One thing to keep in mind with the SE mount, however, is that the power jack can lose connection, which will shut down the mount and require re-booting and re-aligning it – however, installing AA batteries in the scope as backup will prevent this issue.
The 4SE’s tripod has a built-in “equatorial wedge” which theoretically allows the scope to be converted to an equatorial configuration. However, without accurate altitude adjustments or any azimuth adjustment to speak of short of picking up or kicking the entire scope/mount/tripod combination, and an equatorial mount is only needed for deep-sky astrophotography – something that the 4SE, with a focal ratio of f/13, is simply not capable of (the mount’s mediocre gearing quality doesn’t help, either).
The biggest issue I have with the 4SE’s mount, however, is that it doesn’t make much sense. The mount is 17 pounds – much more than it needs to weigh – and must be perfectly leveled during setup (especially if you want the SkyAlign easy-align feature to work). It either burns through lots of AA batteries frequently or needs a good, steady source of DC or AC power, and of course has to be actually aligned – all in order to use a scope that in all likelihood will rarely be pointed at objects that can’t be found with the naked eye, a simple star chart, or even a phone app like SkySafari – and all at the price of an 8” Dobsonian which has four times the light-gathering ability, double the resolution and similar setup time at worst.
What can you see?
The 4SE shines primarily on the Moon and planets. You can easily see lunar details just a few miles across, as well as the phases of Venus and Mercury. Mars will show its ice cap and some dark markings when it is close to Earth. Jupiter’s cloud belts, polar and equatorial zones, and Great Red Spot are visible, and its four largest moons, the Galilean Moons Io, Europa, Ganymede and Callisto, will appear as tiny, not-quite-stellar dots – with good atmospheric seeing, you can just see their shadows as they transit across the planet. Saturn’s rings, the Cassini division within them, and some faint, low-contrast cloud bands on the planet itself are no problem, and you should easily be able to catch its largest moon Titan – along with smaller moons such as Enceladus, hea, Tethys, Dione, and Iapetus. Uranus and Neptune are nothing more than turquoise and deep blue dots – you may struggle to resolve the latter as more than a star at all.
Outside the solar system, the 4SE is relatively limited. Most galaxies such as Andromeda, M81, and M51 will appear as vague smudges of varying size under all but the best conditions (Andromeda and M33 will also be unable to fit in a single field of view with the 4SE). M82 is the only one that might show any detail, especially under light-polluted skies – in the form of a cigar shape and dark streaks perpendicular to it. Globular clusters are merely brightish fuzzy balls with maybe the slightest hint of resolution.
A fair amount of open clusters are visible with the 4SE, but many will be visually unappealing to beginners or won’t fit in the field of view. There are also a couple dozen nebulae visible with the scope, but overall if you’re looking for mind-blowing views of deep-sky objects you should probably look elsewhere. Visible does not mean spectacular.
The 4SE does well at lunar and planetary astrophotography – we’ve attached a few images that I took with my 4SE and a cheap 640×480 webcam that I found at a flea market and attached a 1.25” nosepiece and 2x Barlow lens to. Forget deep-sky, however – the 4SE’s f/13 focal ratio, mediocre tracking capabilities, and the alt-az nature of the mount do not allow for good long exposure photos.
For a similar price to the 4SE, there are a number of other fine options you might want to look at, including the following:
- Zhumell Z8/Orion SkyLine 8: Double the aperture means 4x the light gathering ability and double the resolution. Infinitely easier to set up and use. Better accessories.
- Celestron Omni XLT 6: 2” more aperture makes for 2.25x brighter and 50% higher resolution, all-manual and well-made German equatorial mount, wide field of view.
- Celestron Astro-Fi 130: 1.1” more aperture means 62% more light gathering ability and slightly more resolution. Superior GoTo functionality using your smart device instead of a keypad.
- Celestron StarSense Explorer DX130: 1.1” more aperture means 62% more light gathering ability and slightly more resolution. Much faster setup, wider field of view, and easier to use.
Aftermarket Accessory Recommendations
The most important thing we’d recommend for the 4SE is probably more eyepieces. Specifically, a good high-magnification eyepiece in the 6mm to 9mm range such as “goldlines”, the Meade 8.8mm UWA, or another eyepiece such as a Baader Hyperion or Explore Scientific 82-degree. You might also want a medium-power eyepiece around 14-16mm. For the widest possible field of view and lowest magnification with the 4SE, a 32mm Plossl such as the Orion Sirius is our favorite choice.
Another useful item is a real rechargeable battery to run the scope off of – the 4SE uses an enormous amount of AA batteries and will gobble through a set after less than 24 hours of runtime. This makes a rechargeable supply a great investment that will quickly pay for itself. We recommend the TalentCell 600Mah battery and a male to male power adapter . You can use Velcro, zip ties or duct tape to secure the battery to a tripod leg.