Telescope Reviews

Page 40

 By Ed Ting 

Updated 10/22/16, 1/12/17

Click on a Telescope Below:

1) Orion 180 mm f/15 Maksutov OTA   (aka Skywatcher 180 Maksutov)  10/8/16, 10/22/16

2) Explore Scientific AR127 OTA    10/22/16


1) Orion 180 mm f/15 Maksutov OTA   (aka Skywatcher 180 Maksutov)  10/8/16, 10/22/16, 1/12/17

($1199 direct from Orion.  Includes OTA, 8X50 finder/bracket, visual back, dovetail plate, soft carry case extra)

Tucked away in the corner of the Orion catalog is this intriguing OTA, which you may have missed on your way to their big Dobs and fancy computerized telescopes.  Although it's "only" a 7" Maksutov-Cassegrain, the tube weighs 15 lbs and measures about 19" long.  In other words, although it looks like a typical 8" SCT, it's actually about 2 lbs heavier, and 2 inches longer.  Those of us who grew up lusting after a Questar 7 experienced sticker shock (the good kind!) when we saw the price - $1199 from Orion (the speckled blue Skywatcher version sells for about $1275.)  $1200 isn't pocket change, of course, and this 180 mm Mak costs more than your run-of-the-mill 8" SCT, but try pricing a Questar 7. Along with the sometimes-available Meade and various Russian Maksutovs which lap at our shores, this Orion is your only option in an affordably-priced 7" Maksutov.

Maksutovs have a small but loyal fan base.  They're sometimes thought of as niche products, made for people who like to look at the planets, the moon, and double stars.  And while their long f/ratios usually make them poor choices for photography, am seeing some really superb lunar images out of these 180 mm Maks lately.  When you're photographing something as bright as the moon, f/15 doesn't matter; you've got enough light.  Even master lunar photographer Robert Reeves now uses one of these (he has the Skywatcher version) as his primary imaging OTA.  


Unpacking the unit, it's clear this 180 mm Maksutov is a better-made product than the cheaper Apexes in the Orion catalog.  The scope has a heft and seriousness to it.  At 15 lbs, the scope will work on an AVX-class mount.  With the 8X50 finder, diagonal, and eyepiece installed, it will just barely balance with the mount's supplied 11 lb counterweight.  So mechanically, you can treat the thing as you would a conventional 8" SCT.  If you have a Sirius, Atlas, GM-8/G11, etc, you will be in good shape.  It should be fair to point out that club member "Old Dan" used his all the time on a CG-4 outfitted with a special shaft extension.  That sounded a little top-heavy to me, but he assures me the scope is steady in this configuration.

Like the Questar and the ETXs, the 180 mm Mak has a proprietary visual back.  It looks as if you could thread on a 2" SCT back, but those are slightly too big.  So you are stuck in 1.25" mode with the scope. In fact, unthreading the supplied visual back reveals a tiny 24 mm hole.  The interesting part of this is if you buy the Skywatcher version, they supply you with a 2" diagonal.  I'd be interested to see if the Skywatcher version will fully illuminate the field of a big 2" low power eyepiece.  Scopestuff does sell adapter rings for use on Orion Maks at  I haven't tried them, and you need to read the description on Scopestuff's page carefully, but it does appear you can make it work with 2" accessories if you are diligent.

One other thing worth mentioning - A Maksutov requires a slightly larger-than-spec primary to gather the full amount of light, a result of the corrector plate spreading the light out slightly.  Depending on where you look on the internet, the actual light-gathering ability of this scope is actually somewhere in the 170 mm - 175 mm range.  I didn't care about this, as the scope produced superb images that were plenty bright for what I needed to see.  Also, if you're comparing this Orion Mak to the Meade 7" Mak, or some other similar scope carrying a 2" diagonal, the image scales will be off, as you've got to move the mirror more to accommodate the increased light travel of the bigger diagonal.


Size comparison, 8" SCT and Orion 180 mm Maksutov


Visual back comparison, 2" SCT vs proprietary Maksutov unit


Maks are legendary for their long cool down times.  Although you can treat the 180 mm Mak like an 8" SCT from a mounting perspective, thermally you need to treat it as if it were a C9.25, or perhaps something even larger.  I have a 3.5" Questar and an ETX125, and I never think twice about having them cool down.  But the 180 mm Mak seems to belong in another class, thermally.  It can take a long time for those two big hunks of glass at both ends to cool down.  The first night I had it out, it still hadn't cooled down after almost 90 minutes.  Defocusing a star revealed a plume of light, like a candle flickering in the wind.  The next night, I set it outside in the shade three hours before using it.  That did the trick.  So over time, I trained myself to set the scope outside (I kept it inside the case) if I planned to look through it.

The star test was excellent.  Spherical aberration was nearly absent.  I had to crank the power up to over 250X to detect any differences between the images inside and outside of focus, and even then it was small.  The scope's collimation was also excellent (you can adjust collimation via little screws in the back.)  The scope's previous owner, Mike T, did mention a very slight miscollimation, but it only shows up over 300X, and only when the scope is out of focus.  In focus, he says he never detected any trace of miscollimation.  I wouldn't even mention the issue with collimation, except owners of Maksutovs have a tendency to run their scopes at high power.  Some of you have complained about slight image shift in your samples of this scope, but this one is practically perfect.  Again, I wouldn't mention it, except Mak users will sometimes run at high power, and at 300X+ you are going to notice everything.

The ancient Greeks had a saying that roughly translates to "Know Thyself."  Well, after fifty-plus years on this planet, I am not sure how much I know Myself, but I do know that when I get a scope, I tend to use it at lower powers, for wide field views.  Thus the 180 mm Mak took me out of my comfort zone.  That's OK; we tend to learn the most when we're taken out of our comfort zones.  For a couple of weeks, I spent a lot of time looking at the moon, Saturn, and double stars.  It's a good feeling heading out to observe with the full moon up, knowing it doesn't matter.  For planetary and most double star work, you don't care if the sky is a little bright.

Saturn was fabulous, even setting low in the west.  The scope's 2700 mm focal length took some getting used to.  It's like having the aperture of an 8" SCT and the focal length of a C11 in the same scope.  A 20 mm Plossl becomes a planetary eyepiece.  A 13 mm Nagler becomes a high power eyepiece.  Albireo looked great - two pinpoints, one orange, one blue, with a dark blanket of black behind them.  I also liked the wine-colored secondary of Eta Cass.  Delta Cygnus was an easy split, even with its large magnitude difference.  Mike T reports he has split Zeta Herculi with it.  The problem with Z Herc isn't the modest 1.3" separation (2016 stats, the pair changes visibly on a short time period) it's the fact that the secondary has a nasty habit of appearing right on the first diffraction ring (Delta Cygnus often has the same problem.)

Maksutovs aren't generally known as deep-sky scopes, but there's no reason why you can't use it that way.  In fact, the scope's 2700 mm focal length actually helped when looking at smaller objects like the Ring Nebula.  You get the benefit of high power with comfortable "big" eyepieces you usually reserve for low power sweeping.  At higher power, the Dummbell takes on a "football" shape, as opposed to the apple core shape you usually see at low power.  Globulars like M92 and M15 start to take on some real character, and you can start to see some granulation/resolution of the outer members.  Only when I looked at M31 did I feel the need to back off.  A 24 mm Panoptic shows about the largest amount of sky possible within a 1.25" eyepiece, and it's still 112X.

I enjoyed my time with the 180 mm Mak, and suspect you will too.  It's a high quality product and the price is reasonable.  Having said this, I am not sure this should be your first/only scope.  As time went on, I started to feel a little claustrophobic, boxed-into medium/high power.  For relief, I brought out my little Takahashi FS60 one night and looked at M31 in a low power eyepiece.  Ahhhh...  So while I appreciated this scope, I remain loyal to my roots.

Recommended.  Even highly recommended.  Just be aware of what you're getting into.  Know Thyself.



(Gallery follows.  I took some lunar images with a ZWO 120MM, and Saturn with a ZWO 120MC.)


Update, 1/12/17

Reader Peter B writes in.  He has the Skywatcher version of this telescope.  Peter reports that his Skywatcher comes with a 2" visual back, and he can thread on a standard Celestron SCT visual back if he chooses.  The baffle opening is 33 mm (larger than the Orion's.)  For viewing, he says he can get almost 1 degree, albeit with some vignetting if you know where to look.  The good news is that at f/15. you can use a 2" 56 mm eyepiece without worrying about exit pupil issues.


2) Explore Scientific AR127 OTA   10/22/16

($599 street.  127 mm f/6.5 achromatic refractor.  Includes OTA, 8X50 finder/bracket, rings, carry handle, dovetail plate, 2" dielectric diagonal) 

It's been a while since I've played with a large achromat.  Having developed "expensive eyes" for apos, my refractor world usually stops around 4".  I didn't know what to expect here.  I liked the 6" AR152, but was disappointed by the soft optics of a recent AR102 I saw.  I needn't have worried.  Sometimes you just know.  When someone handed me the AR127, there was something about its heft and solidity that reassured me.  But the biggest giveaway was the dovetail plate, riddled with bite marks that indicated it had been used a lot.  Bad scopes do not get used this much.

The AR127 comes well-appointed.  The dew shield is impressively oversized, and it comes complete with rings, the aforementioned dovetail plate, and a convenient carry handle that left me wondering why more scopes don't have one.  You can collimate the lens cell, and the tube is baffled inside.  The 8X50 finder's optics are a cut above some of the generic junk you see out there these days.  The focuser is a large two-speed Crayford-style unit with a 2" dielectric diagonal at the end.  Both the scope and diagonal have serial numbers, another reassuring touch.  Everything about the scope indicates that whoever designed it expected the owner to use it.

I have many maxims which I live by, and which I will spout to anyone within earshot who is willing to listen.  These include: Big pianos are always better than small pianos.  Any woman who smiles and says "Good Morning" to you every day is worth hanging on to.  Never trust generic Oreo cookies.  Among these missives is one about equatorial mounts which I can sometimes be heard to say - any time you need more than the stock 11 pound counterweight on a CG-5 or an AVX, you are asking for trouble.  Hefting this 15 lb AR127, I became concerned.  This is a serious chunk of metal and glass.  But I needn't have worried.  Even with the 8X50 finder and a 27 mm Panoptic on board, the scope will  balance with the 11 lb weight on my CG-5, and the mount never had any trouble slewing the OTA around the sky.

Let's talk about the elephant in the room.  The scope has false color.  It's not the scope's fault; any big achromat this fast (f/6.5) is going to show some false color.  Depending on which criteria you use, a 5" achromat would need to be anywhere from f/12 to f/15 before false color diminishes to invisible levels.  F/6.5 is very fast for a scope this big.  Having said all of this, I was impressed by how little color I saw, even on some brighter objects.  In fact, most of the time, I forgot about it altogether.  I'm not sure what these guys did (more modern glass?) but a generation ago a 127 mm f/6.5 achromat would throw up much more intense purple halos around bright objects than this AR127.  Only when I looked at very bright objects like Vega or the limb of the moon did I start to notice the false color.  For balance, I should point out that Jupiter wasn't around during the review period.  I'd be very interested to see how it looks in the scope.

The star test was very good and showed just a little bit of undercorrection.  It didn't seem to affect the quality of the images, even at high power, and is excellent for a scope this inexpensive.  Sweeping around the Milky Way near Cygnus was a delight.  I particularly like the area around the cluster M56 near Albireo (I'm reminded of David Bowman's quote from 2001: "It's full of stars.")  Albireo itself showed impressive contrast between its blue and orange components.   I looked at many of the fall objects - the Ring, Dumbbell, M15, M13, M92, M31, NGC 457, and others.  In each case, the AR127 gives you more than a taste of that refractor magic.  You sometimes feel as if you can see forever down into the eyepiece.  It's a deep, dark well down there and with a good eyepiece like a 26 mm Nagler, you could almost fall in.

For someone who's accustomed to a 4" refractor, the extra light gathering ability helped bring in some of the dimmer objects.  M33 just barely showed its spiral arms, even though it was still only about 35 degrees above the horizon.  I could see the Veil Nebula, directly overhead, with no filters.  At higher power, I could make out NGC 7331 in Pegasus.  I took the scope to a school skywatch in Brookline, NH in October of 2016, and it delighted dozens of first time viewers on the moon.  I got the usual comments from kids: "Wow, is that a cannon?!"  The lunar image, below, is very clean for an achromat.  Taking lunar images is an acid test for refractors.  Even some of the good ones will be a little soft.  I showed this image to club members, and only the avid astrophotographers were able to tell this wasn't an apochromat.  

One morning in October I set the alarm for 3:30 AM and got an early look at the winter objects.  Alone, in the dead of night with no one else awake, I spent a pleasant hour with deep sky objects for company - M45, M42, M1, and even a misty hint of nebulosity around NGC 2244, indicating I was seeing the Rosette Nebula.

The ES127 at a recent school skywatch in Brookline, NH


Moon, taken from the Brookline skywatch.  ASI120MM, stitch of 3 images.


Drawbacks?  Only a couple, and they were minor.  Despite the good quality 8X50 finder, I've been more comfortable lately with Rigels and Telrads.  Luckily the scope had a Rigel base already installed on it.  Also, I don't know about you, but when I manually slew a refractor around the sky, I have a tendency to grab the diagonal.  Even with the tension on the Crayford-style focuser set high, I would sometimes pull it out.  I also have some minor concerns about newcomers who buy the OTA only and undermount it with a light equatorial mount.  The various retailers out there do sell this scope in a variety of configurations.  I think you really do need a CG-5, AVX, or stronger to hold this scope.  I also think it's worth the investment, given the excellence of the scope.  

If you're deep of pocket and/or very picky about false color, Explore Scientific does make an apo version of the scope (the ES127) which I like a lot (review coming when I get the chance.)  Otherwise, this AR127 is very happy find, and a nice surprise.


End Telescope Reviews, Page 40