Optical Tube Assembly of AstroMaster 114EQ
The AstroMaster 114EQ is supposedly a 114 mm Newtonian reflector with a focal length of 1,000 mm. This should immediately raise some eyebrows, as the optical tube of the telescope is obviously way too short to accommodate such a focal length.
So what’s going on? Well, the AstroMaster 114EQ isn’t actually a Newtonian. It’s a Bird-Jones (or Jones-Bird, depending on who you ask).
As originally designed by Bird and Jones, this catadioptric design uses a spherical primary mirror with a corrector lens just before the secondary mirror. This design allows for the secondary mirror to be shrunken down, the primary take the shape of a sphere that is easy to make (cheap), and allows for a stout and stubby telescope which has a long focal ratio and next to no coma. At the time the Bird-Jones was designed, eyepieces were simple and coma correctors nonexistent, so focal ratios tended to be on the long side to achieve sharp images.
The Bird-Jones design is outdated and no longer needed. The cheap Kellner eyepieces supplied with many entry-level telescopes today would’ve amazed a 1950s amateur with their quality and work well enough with even a relatively fast focal ratio telescope. Furthermore, Celestron didn’t even bother to execute the design correctly – Celestron’s Bird-Jones design places the corrector lens inside the focuser. This causes two problems.
First, it can’t easily be removed, which is basically required to collimate the telescope precisely and achieve sharp images. The Celestron Astromaster 114EQ does have collimation thumbscrews on the back, but you’ll need special optical tools to reasonably collimate the scope–and you may need to take the corrector lens out.
Second, it means that the spacing between the corrector and primary mirror is not fixed, but instead varies depending on what eyepiece you’re using and also whether you’re nearsighted or farsighted. So the correction is constantly varying depending on what eyepiece is used or even who is looking through the telescope.
The problems don’t end here, though. The correctors in these scopes are incredibly cheaply made, and aren’t remotely close to the right shape, being glorified cheap Barlow lenses. As a result, the 114EQ cannot achieve decent images even when well-collimated, which itself is hard to do.
Moving on to the mechanical aspects of the OTA, we come to another problem: the plastic castings. The giant casting with the AstroMaster logo that protrudes nearly halfway along the tube, as well as the area around the focuser, means that you cannot slide the tube in its rings to achieve balance on the declination axis in most situations. This strains the mount and is a nuisance while observing as you will always have to tighten the declination axis.
The focuser on the AstroMaster 114EQ is a modest and functional 1.25” rack-and-pinion, mostly made of plastic, apart from the knobs. The finderscope is a standard StarPointer red-dot finder, though until recently most AstroMaster scopes had an obnoxious and often-faulty built-in red-dot finder.
The telescope’s optics are not as good as what a similar-sized telescope with a true parabolic mirror can show, but the optics are honestly forgivable. If this telescope had been fashioned as a tabletop dobsonian, and if the corrector lens was placed in a static position, it might have been decent. Unfortunately, it shipped with a CG-2 equatorial mount, which is a reason why this Celestron AstroMaster 114EQ review is not that positive.
The 114EQ comes with standard tube rings and a very short Vixen dovetail, which would allow you to put the scope on a different mount, although this is the equivalent of putting premium dipping sauce on McNuggets – the prime ingredient is still cheap and the secondary ingredient is never going to compensate for that. One of the rings has a captive ¼ 20 knob, so you can piggyback a DSLR camera on top, but this will further wreck the balance, and is too much for the mount to handle anyway.
The AstroMaster “Newtonians” all come with a 20 mm “erecting” eyepiece just like the PowerSeekers for low power. The eyepiece is almost entirely plastic, has a narrow field of view, and isn’t sharp in the slightest. Celestron includes this eyepiece solely so they can sell it at nature and science stores, under the premise of it being capable of terrestrial viewing.
The other eyepiece included with all AstroMaster telescopes is a 10 mm Kellner. It works fine in most other telescopes, though the 114EQ is, of course, incapable of delivering a sharp image with it.
This is the single worst aspect of the AstroMaster 114EQ. Nothing about this mount is acceptable for this application.The telescope is simply too heavy for this mount. As a result, it is full of backlash, sloppy motion, and slipping. It needs to be balanced just right for the right ascension knob to actually result in slewing along the right ascension axis. On many occasions I would have the telescope pointed just where I wanted it, then I would let go, and the RA gear would drop slightly, the whole telescope would fall down, and what I was looking for would be lost, sometimes requiring minutes to find it again.
The mount Celestron supplies with the AstroMaster EQ telescope is known as the CG-3, though some literature refers to it as a CG-2. Celestron’s CG numbering system is confusing; they should ditch it and stick with the EQ1-8 system that other companies use.
The CG-3/CG-2 is of the run-of-the-mill, cheap, and German equatorial design, with tiny useless setting circles that are little more than decoration. It has 1.25” tubular steel legs and lots of plastic castings on the tripod. The mount also has a Vixen saddle so it can accept other optical tubes interchangeably with no tools needed.
The CG-3 has flexible slow-motion cables for both axes and fine adjustments in altitude, and has an azimuth for accurate polar alignment. You can also equip the mount with Celestron’s logic drive for hands-free tracking.
The telescope has two useless setting circles for Right Ascension and Declination. In theory, these are used to align on a given object and use them to find a different object by moving the telescope until the RA and Dec displayed on the circles match that of the target object. In practice, they’re nowhere near precise enough to get you to the object you’re looking for–a star-hop is more fun. To make matters worse, they don’t always turn with the telescope, sometimes they slip.
German equatorial mounts can often place the eyepiece of a Newtonian in awkward positions, and you must rotate the tube in its rings to reposition it somewhere more comfortable.
Normally when doing this you’d have to worry about accidentally sliding the tube forward or backward when the rings are loosened, and thus possibly ruining the declination axis balance, but since the optical tube can’t really slide far in either direction and the balance is so messed up anyways, this is a non-issue.
Also, an equatorial mount is a terrible idea for a beginner telescope. Most beginners have a relatively poor understanding of the motions of the night sky (something which can be improved by constantly observing the sky!) and you must have an understanding of such motions to correctly use the mount. To use it correctly it also requires several minutes of setup and alignment.
The optics in the AstroMaster 114EQ are so bad you can completely forget about taking decent pictures with it. Even if this were not the case, a camera, whether directly coupled or piggybacked, would ruin the balance and strain the CG-3 mount too much.
Should I buy a used Astromaster 114EQ?
Since these telescopes are often hobby killers, you will occasionally see them crop up on eBay or craigslist for much cheaper than its original price. If you can get one for under 80 dollars, I’d say it might be worth the cost. If you get one as your first telescope, you’re risking it being a hobby-killer, as the mount can be very frustrating. However, it may be possible to fit the telescope tube on a tabletop dobsonian base (they sometimes crop up without a telescope tube on eBay), or you could build your own dob base out of wood and Teflon. In that configuration, it might be worth it.
What to see?
The Moon is always nice to look at through a telescope, and there’s no exception here. You can see fairly high detail in individual craters, but it’ll always look softer and fuzzier than it should–not the crisp image you’d expect from a good telescope.
There are dozens of deep-sky objects to look at if you can deal with the annoying mount. The Orion Nebula looks good in pretty much any telescope. Lots of double stars can be split as well.
Nothing in this telescope is as clear and crisp as it should be, but the optical flaws are not the worst part of this telescope, the mount and the price tag is.
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