The Optical Tube Performance
The NexStar 8SE optical tube is an 8” f/10 Schmidt-Cassegrain, otherwise known as the C8.
Celestron has been producing C8s in basically the same format since 1970, when the orange tube C8 made its debut – Celestron did produce a blue and white “C8” as early as 1965 but these scopes were only available at f/12 and f/17 and are very rare.
Although the scopes have undergone revisions in the exact design of the tube as well as now being featured with Celestron’s StarBright XLT coatings and Hyperstar compatibility, the C8 is more or less the same scope nearly forty years later.
The 8SE scopes are pretty good optically, though collimation can be tedious as with any Schmidt-Cassegrain – you must point the scope at a star (or an artificial equivalent), defocus it, and adjust the three small screws on the secondary mirror until everything is lined up. You can replace the screws with thumbscrews such as Bob’s Knobs to make things easier, but the thumbscrews seem to cause the scope to become miscollimated more often and interfere with attaching the lens cap.
Speaking of the lens cap, it’s a nice plastic affair that twists and locks into place – a feature present on all Celestron SCTs since the 1980s.
The NexStar 8SE has a long Vixen dovetail bar on the side of the optical tube, but it is largely decorative in purpose as the scope will only really balance with the dovetail slid all the way or nearly all the way forward in the saddle.
Interestingly, the focus knob of the 8SE is on the bottom side of the tube when used on the stock mount. I infer that this is because it would cost Celestron a fair amount of money to bother with rotating the dovetail 90 degrees for one scope model so they simply elected to have it made on the same production line as their equatorially-mounted scopes, which have their dovetails on the bottom of the tube and the eyepiece 90 degrees away on the right side.
The 8SE’s moving-mirror focuser does cause some image shift (wobbling of the primary mirror on the rod causing the field of view to jiggle when focusing), but nothing too severe.
The back of the 8SE optical tube has the industry-standard Schmidt-Cassegrain threads, which allow you to attach a variety of accessories such as a 2” star diagonal, focal reducer, DSLR T-adapter, and various other items.
Reviewing the Accessories
The NexStar 8SE comes with a single eyepiece – Celestron’s “E-Lux” 25mm Plossl – and a 1.25” star diagonal and visual back. The included 1.25” diagonal is a prism of very high quality.
While the 25mm Plossl works well for low power, you will probably want a 2” diagonal and wide-angle 2” eyepieces for low powers, and various 1.25” eyepieces for higher magnifications. You can attach a 2” diagonal simply by unthreading the 1.25” visual back and threading a 2” diagonal for SCTs on in place, or by purchasing a 2” visual back and a 2” diagonal with a 2” nosepiece – the latter is less convenient but there are more refractor diagonals to choose from.
The NexStar 8SE’s finderscope is a simple red dot finder, which is all you need to align the GoTo system – after alignment is complete, you don’t really need a finder at all.
The NexStar 8SE’s mount is the same as supplied with the NexStar 6SE. While it does work pretty well with the C8 optical tube assembly, it is not ideal to support the telescope and can be jiggly at high magnifications, particularly if you are using any heavy accessories or have the legs extended. This also presents the problem that you could knock the scope out of alignment if you’re not careful. Celestron’s Vibration Suppression Pads, while mildly inconvenient to deal with, will alleviate most of the jiggles with this scope and they’re really not a huge problem.
The 8SE mount takes eight AA batteries, but I recommend only using these as backup – get a portable 12-volt DC power supply and cord (Celestron even sells some as the PowerTank meant specifically for astronomical use). However, you should always keep AA batteries in the scope’s battery compartment, because if external power is lost accidentally and there is no internal backup the scope will have to be rebooted and re-aligned.
The 8SE’s hand controller contains a catalog of about 40,000 objects. While the 8” aperture can show an impressive amount of deep-sky objects and double stars, most of the 40,000 objects in the NexStar database are simply uninteresting, unaccompanied stars.
The 8SE mount has a Vixen saddle and thus it can in theory take other optical tubes, but nothing besides a similar-sized or smaller Schmidt-Cassegrain or Maksutov-Cassegrain will be able to clear the base.
What All Can You See?
Once initial setup, alignment, and collimation are out of the way, the 8” aperture of the 8SE will show you a lot.
In the solar system, you can explore:
- Mercury and Venus’ phases
- The Moon’s ridges, faults, valleys, mountains, flatlands, craters, and more – any feature bigger than a mile is visible provided good atmospheric conditions and collimation
- Mars’ albedo shading, ice cap, and dust storms
- Jupiter’s bands, cloud belts, Great Red Spot, and the moons as tiny colored disks
- Saturn’s rings and the division in them, its cloud belts, and a half dozen moons
- Uranus as a small turquoise disk, with possibly a moon or two
- Neptune and its moon Triton
Outside the solar system, you can complete the entire Messier catalog given half-decent skies, and even the Herschel 400 catalog with effort. Thousands of galaxies and star clusters as well as hundreds of nebulae are yours to explore – all readily accessible with the 8SE’s GoTo system.
How Good Is the 8SE For Astrophotography?
The NexStar 8SE is capable of very good lunar and planetary astrophotography with either a CCD camera or a DSLR – both need a 2x or 3x Barlow lens for optimal sampling and the latter requires a T-adapter. Just take a couple minutes of video and process it with the free programs Registax or AutoStakkert.
Simple deep-sky astrophotography of objects like the Orion Nebula and Andromeda Galaxy is possible with the NexStar 8SE provided you obtain Celestron’s f/6.3 reducer and keep exposure times to under twenty or thirty seconds – longer than that and the alt-azimuth mount’s field rotation and small inaccuracies of the tracking will blur your images. You could buy a Starizona HyperStar and do longer exposures (as well as getting a wider field and more detail with the same exposure length), but an equatorially-mounted apochromatic refractor is probably a better choice for the beginner astrophotographer than the 8SE with HyperStar.
If you can afford the high price and don’t mind the tediousness of aligning a GoTo system and collimating a Schmidt-Cassegrain, the Celestron NexStar 8SE is for you.