Skywatcher Explorer 114/900 EQ2 (4,5")

[assasincz]

It has occurred to me recently that despite writing about it numerous time, I have never really taken my time to review my 4.5” Newtonian – shame on me! Well, it was the first telescope I bought upon re-entering the hobby some years ago, and despite having a 12” dob, I have clocked most of my observing hours on this modest scope. It has allowed me to learn a great deal about astronomy equipment, celestial mechanics and, most importantly, it has been my guinea pig for astro DIYing, so, a great companion.

WARNING: Objectivity disclaimer ahead.

Perhaps, I am too fond of it, but I will try my best to review this scope as objectively as I can. Before I go on, let me point out that I am well aware that the telescope, though good, is not perfect, in parts or in its entirety, so I will try to point out all of the aspects that a potential buyer might find either satisfying or annoying.

First of all, it is fair to say that I have noticed that this particular telescope is certainly not a recommended purchase (primarily due to its mount), but let me stress out that if you are interested in getting an entry-level telescope, you can get one of these dirty cheap second-hand. I myself got mine for the equivalent of some £70, which I don’t think is too bad, and I have even seen people selling it for less than that. A guy sold it to me, saying that it’s not more than a toy, but to be honest, I reckon he underestimated this scope’s potential. However, as I will point out later, you have to do some additional purchases in order to truly utilize its full potential.

Optics

The telescope is a reflecting telescope with a 4.5” (114mm) spherical mirror, having a focal length of 900mm (114/900). This means that it is a fairly “slow” F8 scope, which means that it is not demanding on eyepieces and delivers a fairly consistently sharp field of view. The primary sits, as expected, in an adjustable metal frame, with collimation thumbscrews and locking screws, so standard collimation and adjustable rules apply. I would suggest replacing the locking screws with some quality screws of same spec, because the original ones are quite disintegratey. The primary mirror is, on its non-reflective side, covered with a black piece of paper, which, I suspect, hinders the cooling down procedure, so just remove it. There is also no centre spot on the primary, which makes collimating it tricky, but you can either stick to star collimation, or make a centre spot on your own. All you need is a tiny black painted washer and some skill. The secondary mirror holder is a single vane assembly made of solid metal, which is mounted strictly in one place; this means that if you don’t screw around with it violently, it holds the secondary perfectly cantered in the OTA. What is more, single vane assembly means that the scope does not produce the traditional cross shaped diffraction spikes on bright stars, and you really only notice a single sharp spike on objects like Vega, or Venus, which I think is quite good. The secondary itself tilts in all directions imaginable, but I would advise putting a reasonably sized metal washer where the adjusting screw press against the secondary mirror cell – the surface is plastic, which means that the screw make dents in it and consequently, it limits the rotational adjustments of the secondary.

OTA

The 900mm focal length results in quite a long OTA (unlike the barlowed shorter versions), which brings with it some intrinsic issues. Such a long OTA on a wobbly EQ mount (which I will get to shortly) means that any vibrations are greatly magnified and the entire things wobbles, and it does so for quite some time before it gets stable again. This means that focusing, making slew adjustments or even when you nudge an eyepiece slightly, all these processes will drive you nuts. Furthermore, the stability of the scope is quite susceptible to gusts of wind, which results in even more judder. Overall, if you are not gentle, observing with this scope may be a quite wobbly experience. However, there are ways to redeem the wobbliness – you can get a motor focuser, like I did, which makes the whole observing experience way more pleasant (the details of how to stick such a thing to this scope are here ). The OTA length also means (surprise, surprise) that the scope is quite ungainly. The inside of the OTA has been painted (in my case anyway) with matt black paint, which, despite all the best efforts, reflects some residual stray light. So, with me being as DIY-y as I am, I have flocked the inside of the scope to improve it. The details on how to do it are here )

Focuser

The focuser assembly is, I think, the weakest link in the optical assembly. Being only for 1.25” eyepieces, it’s made from plastic, and the focuser tube is quite wobbly, which means that no matter how hard you try, you will probably never be able to collimate the damn thing perfectly. It also means that using big and heavy eyepieces (like e.g. Hyperions) is dumb and counterproductive. It is therefore best to stick to 1.25” eyepieces only.

Finder scope

The finder scope! Oh, the damn finder scope! That “thing” that came with it, disguised as a finder scope, is totally useless. Seriously, it is a 30mm finder made completely out of plastic (and I suspect that the lenses are too), which gives very poor image. What can you point it to? Ehm, some planets, the moon, perhaps a bright star or two, but that’s it! You soon find out that it is the finder scope that limits what you can see, or find. Star hopping method is out. Obviously, some finder is better than no finder but for me, upgrading on a decent 8x50 finder scope was the number one priority.

Eyepieces

The scope came with two stock eyepieces which are as familiar to you lot as the sky is: 25mm and 10mm psllososlss. The 25mm one is really not too bad, despite its narrow field of view, but it gives quite low magnification (36x), which means its only good for quick sky survey and you soon find yourself in need of higher magnification EP. The stock 10mm is, to be honest, quite poor. I would not mind the narrow field of view, but when you aim it to bright objects (planets, or the moon), the view suddenly gets a sort of a “milky” haze to it, and reflections inside it are appalling. So, with the above mentioned, it is good to get some extra eyepieces. I would advise getting 17-20mm one with a wide FOV, and a 6mm one for planetary/double stars/lunar observing. After that, I guarantee you will never touch the stock ones again.

EQ2 Mount

The scope sits on the most basic equatorial mount imaginable – the infamous EQ2. Ladies and gentlemen, I put it to you, this is the weakest link of the whole setup, by a long run; but, surprisingly, there is something good about it too. Ok, so the EQ2 is the weak spot, making the whole setup very wobbly. I can imagine that EQ2 is sort of good with some short tube Newtonian, but with OTA almost a meter long, it is quite poor. Basically all the downfalls I described in the OTA section are down to the mount. The setting circles are useless, decoration really, and the limited range of fine adjustment on R/A axis will drive you crazy. Then, the body of the mount is made of alloy not really suitable for the job – it is quite fragile, and if you over-tighten your locking bolts, hoping that it will magically stiffen the whole thing, there are chances that something “snappy” will happen – like it happened to me. Luckily, I was able to machine-out a replacement of the broke R/A locking screw assembly, so no biggie. Anyway, be very careful with the locking screws. Generally, you will soon find out that you will need to re-grease the mount and tighten all of the screws once in a while for the mount to work the “best”, although miraculous “improvements” are, in this case, strictly subjective. Surprisingly, there is, and I kid you not, an upside to this mount; not in itself, but in what it represents. It is an equatorial mount, which means that if you want to use it properly, you have to learn how to operate it, which means that you get into stuff like polar alignment and fooling around with setting circles, which means that you learn a great deal about movement of the celestial sphere and celestial navigation coordinates, which I reckon, is a good thing. If you finally get down to this EQ mount business, you will eventually reach a point of enlightenment, when you suddenly realize how the sky works and what is really going on, which is, in my book, priceless. Alternatively, you can just use it as a clumsy alt-az mount.

Tripod

The tripod is the one thing that is least criticize-able, I think. The legs are made of aluminium and the whole tripod is fairly stable, although with its legs fully extended, it is unnecessarily high and prone to stability problems. The best option is to have the legs extended half-way for when you observe standing up, or fully retracted, when you use an observing chair of some sort. It even has a metal tray in the middle, which I think is very handy. It is even fairly light. What is more, it can even serve as an emergency photographic tripod, should you ever need one, although you would have to mount the camera on top of the EQ2, and, has been proven above, the advantages of this are questionable.

Observing - Planetary

Although 4.5” diameter mirror does not sound like much, I dare say that this scope is fairly capable. It is said that “slower” telescopes are better for planetary observing, but, to be honest, I have no authority to judge; although I have both F/8 and F/5 telescopes, they are different sizes. Either way, I have to point out that this 4.5” telescope reveals a fair amount of detail, even when compared to a 12” dob. Even though that the image is not as brightly defined, I am able to resolve a great deal of Jovian details, provided that the seeing conditions and atmospheric distortions are at their minimum. There is no problem in spotting the Great Red Spot on Jupiter, and some fair amount of detail beyond the main equatorial belts – I have a sneaky suspicion that the main limiting factor of this scope’s planetary performance are the eyepieces you use. Nevertheless, you will be able to resolve craters on the Moon as small as 2km in diameter, which, I think, is quite admirable. Naturally, there are some visual limitations to the resolving capabilities of this telescope due to its primary mirror diameter, especially when compared to a larger diameter mirror, but I dare say that the differences (eyepiece quality aside) are not dramatic.

Observing - DSO

Despite all my prejudices, the scope has proven itself many times when it comes to DSOs. Naturally, the most critical element to affect what you can see through your telescope is the quality of the sky under which you are observing, and this rule is even more valid when you have a modest scope like this one. Nevertheless, it should be pointed out that with a 4.5” diameter mirror, you do not need to limit yourself to just Messier list, but you will be able to see quite a few NGC or IC objects as well. Obviously, the telescope, due to its primary mirror diameter, performs the best on smaller objects with high surface brightness, like smaller, brighter galaxies, or planetary nebulae. It is with more diffused low surface brightness objects where this telescope starts to struggle, so objects like M33 or M101 might present a problem. Furthermore, the image the scope delivers is not as bright as with larger scopes, so low contrast delivered will limit what you will be able to resolve, so, for example, it is only with globular clusters such as M13 that you will be able to resolve individual stars and the overall granulation, but dimmer objects will appear as fuzzy blobs with no internal structure. Despite this, you might be pleasantly surprised with this scope’s capabilities.

Upsides

• Very cheap (especially second-hand)
  
• Decent optics
  
• Single-vane secondary mirror assembly
  
• “Slow” telescope (not demanding on EPs)
  
• Fairly good 25mm stock EP
  
• EQ mount teaches you how the sky works
  
• Stable, light tripod
  
• Good for planetary/lunar observing
  
• Surprisingly good with DSOs
  

Downsides

• Long OTA
  
• Occasionally shabby build quality
  
• Wobbly focuser, only 1.25”
  
• Poor stock finder scope
  
• Poor 10mm stock EP
  
• Undersized, wobbly and quite fragile EQ mount
  
• Complicated operations
  
• Poor with low surface brightness objects
  

Suggested modifications

• Motor focuser
  
• Decent finder scope (8x50 perhaps)
  
• Flock it!
  
• Remove the black piece of paper behind the primary (improves cooling)
  
• Replace poor quality screws with better ones
  
• Better eyepieces required
  

[Terrynak]

Wonderful review! I bought a 114/900 Newtonian, the Celestron Powerseeker 114EQ, for only US$110 new (or £72) about a month ago. Looks identical to your Skywatcher, except that it's painted black. It came with an EQ1 mount, but I mounted mine on a Skywatcher AZ4 alt-azimuth (marketed as the Orion VersaGo II in the U.S.).

I use my Plossl eyepieces rather than the two that came with the scope.

I took out the primary mirror and center spotted it, then put a notebook reinforcement ring over the spot. Also loosened the screws holding the mirror clips to alleviate astigmatism.

As you mentioned, it's surprisingly good on DSO's. A few days ago, I picked out 9 non-Messier galaxies ranging from a visual mag. of 9.8 but low surface brightness of 14 (NGC 4214 in Canes Venatici) to one with a visual magnitude of 11.9 but a high surface brightness of 12.8 (NGC 5532 in Bootes). M13 and M4 globulars showed nice resolution at 150X.

Haven't had optimal seeing conditions for planetary viewing yet, but was able to clearly see Saturn's Cassini Division at 143X, plus a couple of satelllites (including Titan of course).

Looking forward to spending many nights under the stars with this scope in the coming weeks and months.