on May 24, 2012
The Sky-Watcher Pro 120ED APO is very simply a first class telescope. I did a lot of research before purchasing and when I saw the amazingly low price on Amazon I jumped on it immediately. It comes in a first class aluminum carrying case that is well padded and includes a 2" diagonal and two eyepieces as well as the finder scope. Frankly I wish the finder had an illuminated reticle, but it is a good piece of equipment. Unlike Cassegrain reflectors there is no requirement to collimate mirrors or make other difficult adjustments. The Crawford two speed focuser works like a jewel.
My final decision was made after reading a review on an astronomy website in which the reviewer had been using an 8" Cassegrain for years and at a star party got some time on the 120ED. He realized that he was seeing both moon images and deep space images better and easier on the 120 despite the smaller aperture. He reported doing some research and concluded that between the blockage that the front mirror causes in a short tube reflector and the light loss from the extra trips though glass at each reflection, the 120ED was actually transmitting more light to his eye than was the 8" Cassegrain!
If there is a drawback it is that this scope is long. That means that in an overhead shot it is possible to have a camera or diagonal hit a tripod leg. That, of course, throws off the alignment and requires a complete new set of alignment shots. The problem is generated by a combination of the overall length and the need to extend the Crawford focusing tube, particularly when doing astrophotography. The solution is to balance the scope with the camera or diagonal mounted and the tube extended. That will move the scope forward in the mount and avoid the problem. If a person has been using a short reflecting tube the issue of scope balance is a whole new problem. The way the mounting rings are set up on this scope makes it a piece of cake. Just loosen the thumb screws a little and the scope slides smoothly up and down in the padded ring mounts. The perfectly machined and polished tube surface aids this process immensely.
Overall the scope is very solidly built from the heavy metal dew shield to the Crawford mount and tube. This is a piece of craftsmanship on sale for about half what I would have expected to pay.
on September 28, 2011
I have owned this scope for a few months and use it every clear night that I can. (averaging twice a week) This is a great telescope for the price.
Why would you buy this telescope when you can get something the same size or bigger for a lot less money? The answer has to do with the type of glass used in the telescope lens. It's "Extra-low Dispersion Glass." This means that the picture you see in the telescope will not have the false color (chromatic aberration) found in cheaper refractor telescopes. Less expensive "achromatic" telescopes do not use the best glass - this compromise the colors in the view and also the sharpness. This is NOT just a marketing gimmick - the type of glass used in a telescope is extremely important and well-understood. The 100ed isn't tip-top of the line but it's pretty close. There are similar-sized telescopes that give better views, but they are also MUCH more expensive (Approximately three grand.) The views in this are probably 90-95% as good - most casual users will never miss that last 5%. The 100ed gives awe-inspiring views of the moon (most telescopes will) but also gives very pleasing views of open clusters, globular clusters, and brighter planetary nebula. It's possible to see brighter galaxies, but not with much detail. Any scope this size will struggle on fainter objects. Overall, there is no problem with the views in this scope.
The 100ed comes with excellent accessories (in the Skywatcher version, that is)
1) A very usable case - great for taking to a dark site. It's solid enough for car trips, but don't try sending it through baggage claim at an airport or USPS.
2) A two-inch diagonal. This is MUCH better than the stock diagonal one finds on "department store scopes."
3) Two-inch "crayford" focusser. Cheaper scopes come with plastic focussers that have a lot of slop in them, and are hard to adjust. This one is excellent for visual use. I have not tried attaching a camera to it yet.
4) Finder Scope - The supplied finder scope is very usable and, again, a huge step up from the cheapie plastic ones that come on $200 scopes. It has a great adjustment system that is easy to use for aligning the finder to the main tube. Bonus points for this!
5) The supplied eyepieces are fine, but you may want to upgrade for a newer, wider view relatively soon.
A lot of beginners ignore the quality of the other stuff that a telescope needs to work. That is not a problem with the 100ED, as everything works well together, with little frustration, right out of the box.
One thing to consider, for a first-time buyer, is a mount for this scope. You definitely need one, and should probably go with the sturdiest one you can afford. I use a Skywatcher AZ4, which is OK, but will eventually upgrade. Computer-driven mounts are cool, but not really necessary for most users. They can be flaky and uncooperative, and you need a big battery to use them. Someone on a budget would be better off getting a more stable, hand-guided mount.
Orion Telescopes sells the same basic item from their website. But this is a better deal, because the Orion version doesn't have a case or a diagonal.
A few minor caveats:
The tube is pretty big - it isn't heavy but definitely takes up some space in the living room. Other telescopes are designed to be smaller, but there are tradeoffs involved.
The scope is "slow" meaning the tube is fairly long in relation to the diameter of the lens. This means it is not the best scope to use for astrophotography. A shorter tube (with the same sized lens) can use much shorter exposure times to get an equivalent image. But for visual use, it's great.
This is a wonderful scope for a beginner or for an experienced observer who wants a high-quality refractor without the high price tag. Just get a good mount for it!
on May 23, 2014
The Sky-Watcher Pro 120ED (SW 120ED) is a fabulous instrument capable of serious lunar and planetary study at a surprisingly low price-point. The version currently shipped is the Black Diamond model - with white painted focuser, tube rings, and dew-shield, and a black OTA flecked with gold sparkle. It's actually quite nice looking. How can they make such a bargain scope?
The objective is where the majority of the money was spent on this fine apochromatic refractor. When light passes through a refractive element (like a prism) it disperses into its color components, as the different wavelengths disperse at different lengths. An apochromatic refractor, unlike an achromatic refractor, converges all the frequencies of light at the same focal point (or nearly enough so for the human eye). Achromatic refractors do not converge the blue/violet light very well - so the blue/violet range of light appears as a fuzzy blob around the object you are viewing. It's not an issue with dim objects like globular clusters, nebula, or galaxies, but it becomes a nuisance with brighter objects like the moon and planets. The color that is not correctly focused is information that is lost (subtracted from the resolution of the object viewed). As such there is a great desire to produce apochromatic telescopes for viewing planets - especially in the ~5" range where there is enough aperture to detect fine details.
There are several ways to manufacture an apochromatic lens objective, the usual way being a so-called "triplet" configuration - three pieces of glass mated to gather the light, converge the frequencies, managing the refractive dispersion through the elements. Triplets are obviously significantly more expensive than the other (usually lesser) method of "doublets". A doublet reduces the function of the triplet down to two lenses. Most doublets do not qualify as apochromatic however, they are usually labeled ED (extra dispersion), and are at best semi-apo, but typically just achromats.
So how did Sky-Watcher manage to deliver a doublet objective at a price-point just a fraction of other Apochromatic telescopes? Good question! The answer goes all the way back to a premier telescope manufacturer in Japan, who in the late nineties began shipping "Flourite" refractors. These jewels by Takahashi were amazing instruments of the time, and achieved their very-good color correction by the use of a Flourite glass element in a doublet configuration with a crown flint element. Flourite glass is very expensive, but has come down in price over the years. Flourite allows the blue/violet (upper visible spectrum) to be focused with the green and red, achieving an apochromatic outcome. The dispersion characteristics of the two lenses together are key to this design. It's interesting to note that most of the refraction theory of light goes to Isaac Newton - but he never realized that different types of glass (in addition to how they are shaped) would effect the degree of dispersion of the different wavelengths of light. Too bad - he was so close!
As we've just discussed, all glass is not equal - and there are numerous ratings of the different glass types manufactured even by the same companies, and some companies simply make better glass than others. Early speculation was that the SW 120ED (being so priced) would not use the most premium of glass, and would be a mediocre "semi-apo". But in fact they used some of the best glass currently available (as was later revealed) - Ohara FPL-53 flourite for the back lens, and Schott crown flint glass for the front lens. The usage of Schott glass is not mentioned on the OTA shown on the pictures here on Amazon, but in fact it was used in all of the SW 120ED telescopes, and all currently shipped have a Schott marking right on the OTA (Optical Tube Assembly). So well did this glass work for Sky-Watcher?
The SW 120ED definitely earns the apochromatic label - there is hardly any detectable fringing on bright objects! On the moon there is a barely detectable fringe at high power, and some reddish cast in craters - but this is very minor. There is no detectable false color on the planets! I've owned a number of high-end apochromatic telescopes over the years, but ultimately could not justify their high-cost vs the amount of time I use them. My last such instrument was about the same size as the SW 120 ED (subject of this review), but cost nearly $5,000; it was one of those prized Takahashi Flourite refractors. The SW 120ED provides nearly the same views as that impeccable scope for a FRACTION of that cost. In that regards this scope is the best refractor deal currently available.
All of this money poured into an objective does mean that some corners were cut elsewhere, and this review would not be complete without mentioning them, So I am going to go through the different aspects of the scope.
1. As mentioned above, the objective is jaw-dropping good at this prize - an actual 4.73" apochromatic telescope for under $1,600.
The pretty good:
Add to that some more positives:
2. The included dielectric diagonal is actually pretty good, as is the right angle finder!
3. The OTA is well made - having very good internal baffling reducing stray reflections and glare.
4. The Aluminum Case it ships in is very nice. The scope should be put back into this case, along with the desiccant packages, following use.
One item is mediocre, but expected at this price point:
5. The eyepices could have been better. You probably won't use them long term, as they are not as well corrected as the telescope - in fact if you use the included eyepieces you will see more false color, that is ironically introduced by the inferior elements of the eyepieces themselves.
These I find barely adequate; they are functional, but limit usability:
6. The dew shield does not retract. It is removable by unscrewing it. What this means is storage and transportation of a VERY LONG tube.
7. The focuser is barely adequate for this fine instrument. It will work, with some adjustment of the tensions, but as soon as you put a heavy bino-viewer, CCD camera or DSLR with field-flattener/reducer, or even heavy eyepieces, you will hate the focuser. A good upgrade to it will cost upwards of $400, however it is an easy replacement (anybody should be capable of unscrewing the factory one and installing the replacement).
8. The tube rings are also barely adequate. They are not really wide and strong enough for this OTA, so there will be flexure. For visual usage this won't be an issue - but for extended photographs the flexure will distort your results. An easy fix as well.
And one neutral (almost a negative) item, that some may value more than others:
9. The Lens cell cannot be collimated. However on the bright side - you shouldn't need to collimate it.
I felt it necessary to list these out - but take notice that most of these issues are minor, and of impact only to those doing astrophotography. The most important element, the objective itself and the optical tube, are of excellent and very good quality.
I do have one further note - even though this telescope is lightweight - about 16 lbs with all the goodies attached - you will need a substantial mount, like a Televue Gibraltar for non-motorized push-to use, or a Celestron CGEM for goto. The length of the tube creates a long moment arm - exacerbating minute vibrations at the end of the tube while focusing, and straining motors when slewing and stopping. It's a big scope, even though it's light enough for a singular person to manage.
For the price, getting a flourite doublet apochromatic class refractor, this telescope is easily 5 stars.
Addendum: What to expect in viewing with this instrument:
Stars will be wonderful. If you know how to star test (see Richard Suiter's book, Star Testing the Astronomical Telescope), you will find your scope is at leat diffraction limited. That's better than most! You should be able to split many double stars (resolve the stars into their multiple components, as most stars are binary, having two stars rotating each other - some of them so close they appear to be one star to the naked eye, and lesser instruments).
Planets will drop your jaw: Mars will show an ice cap, with a clear line where it has receded during the martian summer; major geological features will be visible including Syrtis Major; you will occasionally glimpse cloud formations on the Red Planet. Jupiter will show multiple bands/belts, and in moments of pristine seeing you may glimpse festoons and swirls in the bands; the Jovian moons will resolve as disks, and you will see ink-black dots (their shadows on Jupiter) as they transit. Saturn will clearly show the Cassini division; light cloud banding will be visible on on the sphere; you will glimpse the moons; occasionally you will see more rings.
The moon: With this refractor you could do a lifetime of research grade study on the moon. Craters will be finely detailed, including craterlets; surprising levels of detail will be found along the terminator (where the shadow of the earth meets the illuminated disk).
Deep Sky: While some brighter globular clusters will be visible, along with some of the nebular (depending upon how dark your sky is), this scope is not really designed for deep sky viewing. It is barely adequate.
Imaging/Photography for all of the above (including deep sky): SUPERB. With a quality mount (expect about $2000 expenditure) you will get amazing photographs of galaxies, nebulas, and globular clusters - and incredible video of the planets and the moon.
on August 4, 2014
This review discusses the Sky-Watcher Pro 120ED APO scope I received, and only that particular scope.
Unpacking the tube from the somewhat flimsy aluminum case, one is struck by how light weight the tube assembly is. I mounted it on a Celestron CG5 mount, and had to strip the mount of some counterweights, leaving one, ten pound weight half way out the counterweight shaft. Where do the weight savings come from? The thin walled aluminum tube, the very basic objective cell (it's not adjustable), and the light duty, 2" focuser.
None of it is badly made, but nothing screams "quality." Neither do the tube mounting rings, and short mounting plate, either. The finder is a very basic, fairly narrow angle, 8x50 job with lots of chromatic aberration, but it gets the job done. Depending on your eyepieces, you should be able to squeeze about 3 degrees out of the main scope (the finder provides only 5). You may be able to do without a finder.
The focuser feels slightly loose, but it doesn't creep with heavy eyepieces, though I haven't tried the largest of the Ethos line. The coarse focus works for only low power. The fine focus knob is mandatory, and quite useful for medium to high power.
The optics are OK, mostly. Star testing reveals some modest zones, and just a hint of astigmatism. The best way I have found to test for false color (chromatic aberration) is to view bare branches against a blue sky. Blue and yellow fringing is plain to see at 100x. It gets a bit annoying at 180x. Viewing the moon, the color fringing is less prominent. The shadowed side of the craters look very slightly blueish. The lit side looks slightly warmer than the rest of the moon. At 240x one notices that the fringing increases with the turbulence.
I'll give a bit of perspective: I used to own a old Celestron C102 refractor made by Vixen Optical of Japan. Aside from a prominent "hole" in the flint glass element of the objective, it showed the typical chromatic aberration of a 4", f9.8 achromatic objective, i.e. quite a bit.
The old rule of thumb for good color correction for an achromatic objective is that the f ratio should be 5 times the diameter in inches. A 4.7" objective, like Sky-Watcher 120, by that rule should be f24. It's not, of course. It's f7.5, and the color correction is close to a well corrected achromat that follows that rule of thumb. That's what exotic glass gives you.
I mentioned zones previously. They lie at the center and about 2/3 of the way out from the center to the edge. I'm sure this harms the image, but you still get decent views. In the very rare steady moments of seeing, you can hit focus and have a bit of room to play with on either side of focus, while having the image remain sharp. When Saturn settles down, you get some remarkable shading over the rings, and the equatorial belt is prominent; the southern edge looks a bit ragged.
Brighter globulars resolve even in areas of city lighting. Open clusters look nice. What you don't get is that high end refractor steel point image of stars.
Had I received a scope of this quality from Astro Physics, or Takahashi, I would have returned it. However, this isn't an Astro Physics or Takahashi; it's a cheap, Chinese scope, part of the flood of cheap, Chinese merchandise flooding our shores. As such, it's OK. It's given me some nice views.
I'll move on to some recommendations: A Celestron Advanced VX mount (the CG5's successor) would work well with this scope. So would an Orion Sirius EQ-G. They would work even better with the Orion SkyView Pro Mount Extension (although the VX may have lost the CG5's compatibility with it). The extension raises the scope to the correct height, while ensuring that the scope never hits the tripod legs.
As this is a pretty cheap, 4.7" refractor, I recommend some cheaper eyepieces. Yes, exotic glass has shortened the f ratio, but f7.5 is still pretty forgiving. You don't need the latest and greatest, high end design. In short, the Baader Hyperion eyepiece line performs very well, as does the near twin line of Orion Stratus eyepieces.
If you decide to buy the Sky-Watcher Pro 120ED APO, your mileage may vary. You may get a better objective, or your optics may be worse. Generally speaking, Chinese companies like Synta (the manufacturer of both Celestron and Sky-Watcher telescopes) are making instruments available that do what far more expensive scopes did 20-30 years ago. They are moving exotic glass into the mainstream. Many years ago I paid a lot of money for a Celestron (Vixen) C102. In 2014, I paid nearly the same amount of money in absolute terms for a 120mm telescope with better optics.
Update 4 September, 2014: Because of an article on a well known telescope review site (see the comments for the URL), I purchased a well made, 1.25", prism diagonal. Like the review article said, there was less scatter with the new diagonal, and Saturn's features stood out better. What I hadn't counted on were some additional benefits.
The scope's star test improved. The zones in the defocused star images were reduced to the point of being difficult to see. Likewise, the astigmatism I had seen went away completely. One last benefit from the new diagonal: Chromatic aberration dropped by over half. I now get sharp images at 360x, though I don't see any more detail than at 240x.
It appears that most of the scope's flaws were caused by the diagonal supplied with it. Which goes to show: When testing a telescope's optics, do one test with the diagonal out of the system.
on August 30, 2014
I recently purchased one of these Sky-Watcher Pro 120ED APO Telescopes. I wanted something larger than my TSA-102 Takahashi but lighter than my TOA-130. After having this scope for a month, I sold my Takahashi TSA-102. Both that scope and this scope are used for casual back yard observing in the Green color zone. The larger aperture is a nice plus vs my smaller TSA.
The focuser on my scope needed adjustment, as all focusers do, regardless of their cost. Even $600 Feather touch focusers need adjustments, so after about 3 minutes of adjusting the many adjustment on my focuser, the focuser was glassy smooth as it should be.
The tube is painted a beautiful metallic black (black diamond they call it) and worthy of a few coats of automotive paste wax to retain its beautiful finish.
The scope is very lightweight, and has no stability issues when used with my Vixen GP-DX equatorial, which has a weight limit of 22 pounds.
They finder scope is typical Synta, and is used probably more for aesthetics than actual use. At 900mm Focal length, scopes don't need finder scopes. Just put in wide field 2" eyepiece and use the main scope as your finder scope.
The scope comes as a complete package minus the mount. The case it comes in is large and over stuffed with goodies, many of which a veteran astronomer already has. I don't use the case, its just too big and heavy for an 11 pound scope to carry around in, so I put the case in its cardboard box and stored it all.
Optically, the scope is beautiful. Any experienced astronomer will tell you the optics are excellent. It produces very rich true colors from planets like Jupiter and Saturn and the moon with no detectable chromatic aberration. Surface details of Jupiter are not softened by the ED glass, as you see when using Achromatics. Focus is very crisp also, details seem to snap right in focus using high magnification Nagler eyepieces on nights of excellent seeing conditions. Deep space is excellent for 120mm of aperture.
Skywatcher to me is the "High End" Celestron line. Similar to how Lexus is the high end line of Toyota. You see this in their higher quality optics and you see it in their smooth crayford focusers and paint finish along with attention to details. They make several lines of scopes. The PRO ED refractors optically are identical to their much higher priced Equinox line. The Pro ED lines goal was to produce a Fluorite doublet with excellent optics in a very very light weight inexpensive package so they kept the scope as simple as possible without sacrificing optical performance. The Higher end Equinox, optically is the same scope with an even higher quality paint finish, a sliding dew shield for a more compact scope to transport, and a higher quality rotatable crayford focuser. Unfortunately, those added features double the weight and cost of the Equinox scope vs the Pro ED scopes, making the user resort to using a much more robust mount.
I wanted as much performance as I could get, in a scope light enough to mount very solidly on my light weight Vixen GP mount.
Everything on this scope wish designed to give you as light a weight package as you can get, with excellent optics and as such everything works well together if you keep that in mind. The tube rings are typical light weight cast 116mm Orion/Synta/Celestron tube rings but painted white to match the colors of the scope.
Stars focus very tight at lower magnifications and any quality refractor should give you, and as magnification increases, stars remain perfect and beautifully round, again, exactly the way you would expect any high quality refractor to perform.
Visually, and I stress Visually, this scope is as good as any 120mm refractor you can purchase, regardless of price, including the TSA-120 which cost 5 times as much. The TSA should hold stars tighter during astrophotography, since triplet lens systems were designed to satisfy the astrophotographer and the critical eye of the camera.
As a causal back yard telescope, to say something else at 120mm is "Visually" superior optically is just kidding yourself, and is only said to impress others, if you own something more expensive.
Experienced astronomers know quality optics in the first half hr of using an instrument. Light baffling on this scope is excellent, and produces dark luxurious back ground skies which further enhances contrast.
If you buy a scope to impress yourself, and are critical in your optical expectations, this scope delivers that promise perfectly more so because of its relatively low price.
If you purchase a scope to brag about what you own in astronomical forums, and try to impress others who think the quality of a telescope depends on how much you spent on it, then you should spend $6000 on a Takahashi TSA-120 (which is how much it would cost to outfit a TSA to the level this scope comes, including tube rings, diagonal and eyepieces and hardcase ) so you can feel like you are the king of the forums and king of the star parties.
This scope has a very unique set of optics. Fluorite glass matched with FPL-53 Schott glass is why these optics produce such beautiful results.
If your tired of fighting chromatic aberration, and set your goals to a higher standard, to own a very high quality 120mm refractor optical system, you wont be disappointed with this scope.
The reality of this scope, is that the Chinese can now produce extremely high quality optics that can compete head on with the best in the world, Visually, at ridiculously low prices. The differences are no longer about the optics in competitive scopes, the differences are about the type of focuser you choose to outfit your scope with, or if your scope has a heavier optical tube, a higher quality set of machined tube rings, and a sliding dew shield. Visually, none of that maters, because its the optics which define a quality telescope, not its bolt on features.
If you absolutely have to have a premium rotatable focuser for this telescope, William Optics makes what your would need:
sold here also on Amazon. I bought one and transformed the scope into a luxurious instrument.
For the realistic astronomer who has to juggle the expenses of every day life, and still enjoy astronomy at the highest level, this entire line of Sky-Watcher Pro ED telescopes delivers what you would expect in high quality optics, light weight designs, and realistic manageable prices.
...Ralph in Sacramento
on January 3, 2015
This telescope has all the essentials for wider field astrophotography. The fit and finish on my example is very nice. I removed the guide scope and mounted an Orion Deluxe mini autoguide setup in about a minute. I also installed the Orion field flattener to get a good, across the frame image of any stars in the FOV from my NikonD3100. Be aware, however, this setup DOES NOT WORK with a FF camera. I recently purchased Stellarvue's 2.5 in focuser and Field Flattener to allow this otherwise fine telescope to work with FF. With the Stellarvue mods, the only vignetting is minor and is out at the edge of the D610's sensor.
I have this mounted on an Orion Atlas, this setup makes a great combo and are no stress on the mount at all.
on April 23, 2014
Very sharp optics, excellent mechanical construction. Definitely on par with the higher priced models at a more reasonable price. Unlike the previous poster, I see the lens cap as a ridiculously trivial item! Optical performance is where the true value of rating an instrument lies, not in berating it for the type of lens cap it uses!
on January 14, 2016
I received the 80MM doublet APO refractor as a gift and new addition to my rapidly growing astrophotography arsenal. I must add that I've only been doing AP for just shy of a year but I absolutely love it. This little gem of a scope is a must have if you're going to do wider field AP for things such as larger galaxies (like M31) or nebulae of all kinds. Frankly, just about any deep sky object is going to shine in this thing. I wish I had purchased this thing at the beginning of my quest. The view in the eyepiece (despite its 600mm focal length) is even clearer than my 8" Schmidt-Cassegrain, and rivals that of my 12" SCT!!! The lack of a secondary mirror/corrector plate obstruction lets all the light through. For casual observing and DSO astrophotography, I can't recommend this little scope enough especially given the cost! Goes well with the Celestron AVX equatorial mount, and if you're going to do AP, a bahtinov mask (just a few dollars) is a must. Awesome!
on February 23, 2015
The lens cap issue mentioned above is virtually nonsense! As with any precision instrument one must place and remove items carefully to avoid damage! I'm sure that just "ripping" off the lens cap will gouge the dew shield, so just don't pull caps off roughly, without considering the possibility of damage!
on January 9, 2015
This is a Beautiful telescope. Refractors are excellent for viewing double and multiple star systems and for taking pictures of our moon. There are limitations depending on the eyepiece and/or the barlow you use and of course the seeing conditions, I have pushed the power to 225x and the image of Saturn was crystal clear. This scope also gives me great views of Open Clusters.... IE, NGC 869 and NGC 884 (double cluster) in Perseus and M35-M38 open clusters.... I was rewarded with a Beautiful view of Orion's Nebula using an O-III filter also. This Scope was money well spent, and is a great companion to my Zhumell Z10 reflector.....