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Borg "125 ED F/6.4 VI" APO Refractor

Editoral Note

In the review that follows Dave uses the term "Apochromat" or APO to describe the Borg 125 ED. Dave does this as Borg uses this term to describe their doublet ED scopes both in their catalog and on their website. However, in discussions with an optical expert it appears that ANY ED doublet of modest focal length can not be considered an apochromatic refractor. Borg is NOT the only manufacturer who is calling their ED doublet refractors "APOs". In the near future Cloudy Nights hopes to publish an article on "what is an apochromatic refractor?" and will request feedback from readers. Using this we hope to create a reasonable and acceptable definition of an "apochromatic refractor" and use this guideline to better categorize these scopes on Cloudy Nights.

Why Another 5" Refractor Dave? A month or so ago I bought a Borg 125 f/6.4 ED refractor. Why a 125 ED, when I already own a 130 f/6 AP (the best short focal length refractor 5" in current production) and the 130 f/12 APOmax, the best long focal length 5" and an incredible planetary/lunar performer? Good question, and one that my wife asks from time to time when yet another telescope arrives at Casa Novo. The answer is as follows:

I have always been intrigued by possibilities inherent in the smallest, lightest, but largest aperture refractor package for travel and quick use. When I read Brian Murphy's review of the Borg 100 achromat at this site, and saw the pictures, I was intrigued by the Borg modular concept and the light weight. I had seen the 100 ED version at Astrofest this year, and found out the Borg representative (Dale Ibis) had his 'day job' only a few blocks from my office in downtown Chicago. After we spoke, I went through the Borg US website. (www.hutech.com) and became intrigued by what I saw. But I didn't 'bite' at first.

I had heard quite a bit about Borg -- both pro and con. The cons I heard were that the QC was problematical, that the build quality was poor, that the tubes were plastic, and that the scopes could not be collimated after they left the factory. I was also told they did not have a return policy.

Dale said, no as to virtually all of these 'cons.' Beginning with the QC issue, he said the scopes were individually inspected and checked when they were received at Hutech by the owner, Ted Ishikawa. As to the collimation issue, Dale said that the design had been changed so they could be collimated by the US distributor, by Dale, or by a competent owner. (I found this to be absolutely correct, as will be discussed in some detail below.) He also said that the build quality was quite good, as I could see for myself.

I then said, "how good are the optics, particularly the ED series?" Dale replied that they were very good ED doublets with good contrast. He did not claim it was as well corrected as the AP. What he did say next, however was what really intrigued me and 'planted the hook,' He said that the 125mm f/6.4 ED was a scope weighing under 10 pounds, and which would break down and store easily in an overhead storage compartment in a single bag, and mount on virtually anything. Return? If I bought it, and it didn't perform properly, it would be returned for a refund.

Okay, hearing that, I bellied up to the bar, put down the green, and it showed up about three weeks later.

Physical Description and Background -- Borg Refractors:

Unlike virtually any other telescope, the Borg refractors are completely modular in concept, built around three basic 'families' that share some components, 'cross-breed', but are divided into these three families based on the tube diameter. Each family consists of one of more objective lens that will fit on the same diameter main tube. There are multiple tube lengths, focusers (all helical), draw tube, visual and photographic back, and on and on and so forth.

The First Family

The first 'family', consists of a group of objective cells that fit on the Borg 80mm optical tubes. The family, begins with a 50mm ED doublet objective cell. The nominal focal length with the 'standard' tube is an f/10. Weight? An anorexic 1.5 kg (1 kg = 2.2 pound.) The 50 ED is also the best place to start the description of the two major Borg sub families -- the Achros and the ED apos.

The former are the normal type of achromatic doublets. Well done from what Brian and Eric have reported on the Refractor Group and elsewhere on this site, but with the limitations on color correction and ability to handle higher magnification that is (again) typical of any shorter focal length achro. The ED versions are also doublets that use an inner element of ED glass, not specified in the catalog or elsewhere but said to be Hoya glass. As will be discussed below, they are well-corrected ED apos, and not 'semi-apos' or another 'lesser' variation. The contrast is very good and they handle power well. (The only limitation that has been brought to my attention is that they are designed so that they do not perform very well in 'the red' and would need a filter to perform well on Mars observations.)

The next objective (now discontinued I understand) was a 65mm f/6.9 achro. That is followed by the 76 Achromat, a f/6.6 weighing 1.7 kg and an ED version with the same focal length and weight.

The 'joker' then comes into this family at this point - the 76 TR, a 2.2 kg, 76mm f/9.9 triplet that does not use ED glass but is called an apochromat by Borg. Looking at the lens design in the catalog (in Japanese, unfortunately for those of us who do not read that language) this is a classic long focal length triplet design that is intriguing but not listed for sale in the US at the Hutech site. I suppose the owner (Ted Ishikawa) might special order one, but someone else would have to step up for this one, my plate is full just now .

The final members of the 80mm family are the 100 Achromat and the 100 ED, the former reviewed by Brian Murphy at this site and the latter on loan to me for a few weeks by Dale Ibis and hopefully the subject of another review in due course. The Achromat weighs 2.3 kg while the ED weighs 2.4 kg.

The Second Family

The second 'family' uses the 115mm optical tubes. The family begins by attaching the same 100 mm Achro and ED objectives that fits the 80mm tube, but now mounted on the 115 optical tube. The first three configurations are purely for photographic use, and are f/4s (Achro or ED) or an f/6.4 ED only photographic version. The last 100mm on the 115 tube is a visual model, also an f/6.4 weighing 2.4 kg.

Now things get a bit complex. Borg makes several 125mm objectives, all ED and in radically different configurations. The two closest to each other are the visual and photographic versions of the 125 ED doublets at f/6.4. They both use the 385mm main tube and differ primarily in the type of focuser and drawtubes used. The visual version weighs 3.9 kg and the photographic 4.3 kg. Borg then offers an f/4 purely photographic version, using a shorter (208mm) main tube and normally used with a flattener, reducer, or one of the many other components offered by Borg for astrophotography. This version weighs 4.5 kg. The last version is an f/2.8 astrograph, weighing 4kg.

The Third Family

The final Borg family is restricted to a single member, the 150ED f/6.7, weighing a svelte 5.3 kg and using the 140mm main tube - one that separates in the center offering the possibility of a 6" apo that would weigh less than most 4" apos, go into a small case and use a small mount and . . . . okay Dave, one at a time .

Okay, but this description only scratches the surface. While Borg and its US distributer Hutech offer several 'packages' as telescopes, that isn't really set in stone. Each Borg scope is a sum of a series of parts that can be assembled as you want for a given task and then modified or upgraded later. The owner of a 50 ED can upgrade to the 76 ED by simply buying a new objective and putting that on the same OTA. And, while the smaller (50 through 100) scopes come in more or less complete 'packages', the 125 is sold without a focuser. The 150 is lens, cap and tube only.

Why? Borg sells to owners in the more 'sophisticated' market (i.e. over 4") that want to 'customize' their scopes using the staggering number of different focusers, photographic tools, extenders, backs, etc that can be seen in small part at the Hutech website (www.hutech.com) and in more detail in the catalog. So what you buy is a group of components to put together, not what most of us would call a 'telescope.' But that is not a bad thing at all.

Let me illustrate: The photo above shows my 125 ED taken apart down to everything but the visual baffle inside the main tube. (The small circular ring in the foreground is the visual baffle for the focuser.) In the left rear are two optical tubes. The former is the 'standard' 380 mm long, 115mm diameter tube Borg sells in what is known as the 125 ED F/6.4 VI package (part # 8126, with 8125 the photographic version.) That 'package' consists of the 125ED lens cell (shown in the middle of the picture) the hood with cap that says, 'Borg' (shown to the left of the lens cell as you look at the photo), the 380 mm tube (tallest tube in the left rear of the photo), the finder base (the white fitting with the set screw towards the front of the photo), and the visual draw tube (the black anodized tube with the two knurled rings at the right rear of the photo.)

The helical focuser (the heavy duty or MDX version) in front of the draw tube and the 2" eyepiece holder etc in the picture are all components sold separately, as is the quadruple turret in the foreground of the photos and the visual baffle that is not shown, but is inserted into the main tube.

Now the fun part: I am addicted to binoviewing. As with most refractors other than the TMBs, I couldn't get enough in focus travel to use my AP/Baader binoviewer without using a barlow. I asked Ted and Dale for a solution. The neatest out of several they offered me (including one that would have eliminated the finder base and substituted a shorter coupling - which may or may not have worked, didn't try it) was to simply use a shorter, 330mm tube. (The shorter of the two tubes in the left rear of the photo.) As described below, that allowed me to use the binoviewer with the draw tube slid in, but plenty of in focus travel using a series of eps and the AP binoviewer. Normal use with a diagonal required sliding out the draw tube or simply using one of the many extension tubes on the end of the focuser and before the 2" ep holder that are available from Borg and listed on the Hutech site or in the Borg catalog. (The 'complete' scope is shown in the photos. The photo in the case is the scope in its present 'normal' configuration, with the extender to allow use with the diagonal. For use with the binoviewer, as shown in that photo, the extension tube after the focuser is simply unscrewed and the 2" holder attached to the rear of the focuser, with the 2" coupling going into that.)

In other words, you can pretty much tailor the scope to your individual needs as I did. The many possibilities for photographic use are simply staggering, and too many to even begin to list here.

(A Note on Helical Focusers and Draw Tubes) Unlike virtually all other refractors (but in the same fashion as the legendary Zeiss APQs) Borg uses a combination of helical focusers and draw tubes on it scopes. While this seemed a bit odd in first use, they soon became simple to deal with and, after use, a pleasure. To achieve a rough focus, you leave the focuser in one position and loosen the outer ring on the draw tube. You then slide the draw tube in or out until the star/planet/etc is at the point of focus and then tighten the draw tube. The focuser is then used to 'fine tune' critical focus or adjust for changes in different eps.

I found that there are two basic positions I use when observing with this system. I slide the draw tube in towards the objective when using the binoviewer to maximize in focus. When I observe with a diagonal, I slide the draw tube out about half way. The only time I slide it out to its maximum length is when I am star testing and use an eyepiece in the 'straight through' mode.

Once you are used to them, helical focusers are very precise and have a pleasant feel. The amount of vibration transmitted during focusing is very small. I like them and would not hesitate to buy a refractor that used this system rather than a more conventional rack and pinion system.

First impression? The build quality is very good. Not Tak, but the paint on the OTA and the objective cell is smooth and glossy, and the helical focuser is a work of art!!!! The components fit together well, and **** if the whole thing DOESN'T weigh in at under ten pounds!!!!

The "VI" package does indeed weigh about 4 kg. When I put it on the scale, the reading was between 8 and 9 pounds (hard to be exact on a digital bathroom scale, and hardly scientific on my part.) The added weight of the focuser and even a diagonal should mean a 5" apo weighing less than 10 pounds. I see no reason why it won't work in a very light EQ, and my GP-DX won't even feel it. The Giro-2 handles it with ease (it is a 115mm tube, and will use the same tube holder and the rings I have for my 4" Taks.) I may see if the Bogen 410 Geared Head (rated for 13 pounds) and the Bogen tripod will handle the whole thing.

Borg has been criticized for its light weight and use of plastics. Addressing that here, the construction is good, but you will not get the 'built like a tank' feel of a Tak or a TMB or what I am told you get with a Pentax scope. However, the construction is excellent in line with the Borg philosophy of light weight and ease of use. So, like everything else in life, it is a trade off. The quality is there. They don't 'underbuild' but the components are light and rough treatment (obviously) will soon be rewarded with damage. However, the other side of that is that the component nature of the Borg allows everything to be replaced by the owner 'in the field' - as I will relate below.

Plastic? The turret is plastic, and works like a charm and weighs zilch. Cost - with adapter - around a $100. How does it work? Great (its not in the same class optically as the Tak Quintuple turret, but it is lighter - both for the wallet and the wrist.) That is the only plastic component of this scope - and an option at that.

The parts fit together well. And 'assembling' them was easy. The visual baffle for the main tube is a hard plastic, black, knife-edge ring that proved very effective used in conjunction with the other baffle that screws into the front of the focuser. The inside of the main tube is lined with black felt, and the baffle fits in well and does not move about. (I asked Dale why they used this method. That allows you to interchange visual and photographic baffles in the same tube.)

First Light:

Okay, first shock of shocks, I got a new scope and went home expecting typical new scope weather (i.e., clouds, rain, snow, etc.) I got home, the skies were mostly clear (some very scattered high clouds) and the almost full Moon had not yet screwed up seeing near Orion and M42.

Set up the Borg in record time. Went out about 7pm CST. Came in at about 10:30 CST.

Sky conditions were about fair, some high clouds and haze. The Borg 125 is a tight fit, but will fit without that much struggle in the tube ring for the FS-102 (114mm, the Borg is 115mm, the objective is larger than the main tube) and goes on the Giro-2 like nothing. Use the Borg 4 eyepiece turret, load in an 18, a 12.5, a 7.5 and a 5 Tak LE.

Start out on the area around Orion and the related clusters. Scope cools down fast (it is about 20 F but real windy, which isn't exactly helping seeing either.) Catch just a hint of the Gas Giants before they disappear over the Western horizon. And -- surprise -- the contrast on Jupiter is real, and I mean REAL, good.

Is it TMB/Tak level. Doesn't seem so, but not that far off, and considering that Jupiter is almost lost in the junk and the light pollution (real bad to the West) I am not sure if I really can compare one to the other. However, what I saw was surprisingly good.. No shot at Saturn by the time I try, lost in the light pollution to the West.

Now to the 'deep sky.' Star images are crisp and clean. Little round balls, not smears or spikes. No real time to star test, and the seeing is not real great between the Lunar glare and the high winds and intruding clouds. Zip over to M-42, and four nice crisp stars in the Trapezium even at low power. Flip to higher power and see the fifth member of the tribe. The little mirror inside the plastic turret is a lot better than I would expect for a $100 item, and the images remain very nice rotating and raising the power. Put in the 2" back (which has teflon tips on the set screw ends -- NICE TOUCH) and put in the Maxbright. The difference in the extra cost of a good optic now shows up real fast. Still, the turret is a hoot to use and cheap to boot.

Now to test the optics after I get my jollies on Jupiter, etc. No spurious color in focus, and I am not going to try any out of focus images tonight. Over to the Moon. Turret back in. Is that a hint of color at the very edge in the 18? No, seems to go away if I focus more carefully. Use everything down to the 5. No color on the limb in the 5 or 7.5 at all. Contrast. Excellent. Crisp, sharp, very, very pleasing lunar images. Period, no "buts" no qualifications. The contrast is very good and the correction is all that I can ask for. Very nice images. (Please note that this was with the optional visual baffles. The scope comes with a black, felt-type lining in the dewshield, tube, drawtube, etc.but no baffles. For a few bucks extra, you can get a set of visual baffles -- for the OTA and one for the focuser. They are obvious from the photos looking down the tube.)

What is my first take on the optics? This was a brief, three hour 'run and gun.' The 125 came through very well, and while the deep sky was compromised by seeing conditions, the lunar and the brief planetary views were what I would expect in a good ED scope. (At least as good, and, as I recall, better than most ED doublets I have used.) Mechanicals? I love, no LOVE, the combination of drawtube and helical focuser. You can 'fine tune' with virtually no scope shake, and the feel is precise and smooth albeit with a tiny bit of 'rotation' with the heavy diagonal or a binoviewer. No image shift, just inherent in the focuser, and something that I believe can be tuned out.

Was there any negative impressions that first night? The Borg finder I got had optical distortion. No worse than others in the same price range, but my Tak 7X50 fit fine so the Borg finder went back. Is this typical of all the 50mm Borg finders. I don't know.

Second Light, and An Issue Emerges:

My friend Brian came over the next evening, and we both had fun playing with the 125. Brian managed to push the Borg up to about 400 X on the full Moon. Good contrast, good definition, and no color in focus at all including the limb. The color out of focus was minimal. My opinion? The same, and less color out of focus than the only other ED doublet I had spent any time with, the 102 ED Vixen. Jupiter and M42 were again very good and very well contrasted against a black background.

Star test time was where the first question arose. It was very cold when we went out. The first star test on Sirius (not the best of targets for a star test, and not in the best seeing conditions that evening) was poor, but obviously caused by a scope that had not cooled down. Later, the images remained poor and we suspected a collimation problem - a surprise based on how well the scope performed otherwise. We chalked it up to poor seeing.

The scope performed well later, in repeated use. The optics performed well, but I could not get consistent results in my star tests. Brian was also puzzled as we talked - but he liked the scope enough to order a 76 ED from Ted a day or so later.

Speaking to Ted and Dale, they were puzzled. Ted had been delayed in shipping the scope to me because he star tests each of the 125s and had poor weather. He assured me his star tests were excellent. However, he wanted to check the scope to see if had been banged in shipping and asked if I would unscrew the objective and send it to him by overnight at his expense. He said that Dale was coming out to Hutech, and the two of them would check the scope and see if it needed collimation, Dale would help him and then show me how to do it myself. Taking the objective off was easy, and it went to the office with me on the train the next morning. It was at Hutech the following day.

Ted called a day later, said the objective was out of collimation and said that it was one of two possibilities: The first was jostling in shipping. The second was that he discovered that the manual for the 125 notes that extreme cold temperature may require re-collimating the optics. Ted said he would collimate the scope again, but would ask Dale to come out and show me how it was done and, if the weather got very bad again and there was a problem, Dale would help me resolve it.

Learning to Collimate A Borg 125:

The objective came back, and in the milder weather that we had at that point, the optics worked fine. I chalked it all up to shipping, but Dale wanted to come out to check and to drop off the 100 ED for me to look at and possibly review at some later point. Once we got out, the seeing was great but the temperatures dropped like a stone. The star tests at that point (no diagonal, using a 10 ortho in a 'straight through' configuration) had a hint of a pinch from the rapid dip to very, very cold winds and temps on the edge of the lake here.

Collimation, once we got the diagonal out and the extension tubes in, took a whole 15 minutes in real world time and 45 minutes with all the instruction and 'okay, now here is what we do and why' that Dale was kind enough to supply. End result. Shift over to the Trap and the images were crisp and the stars perfect points there and everywhere else we looked. Collimation spot on and optics just fine.

How do you collimate the 125? There are four Allen head screws located on the side of the extreme end of the objective cell. (They are located in the black band separating the lens and the dew shield shown in the photos of the assembled scope. The photo of the components show where they are on the flat rim of the objective cell.) The ED element does not move in the cell. The front element moves in relation to the ED element by the 'push pull' of the four screws - loosen one, tighten the other, and the element moves in the desired direction.

The collimation issue last night was resolved with even less fuss than the simple means of collimating this scope Dale showed me how to do last night. That can be done using a Cheshire with the lens cap in place, using an artificial star indoors assuming you use the appropriate distance and light source, or as we did last night - one person watches the star image and the other adjusts the Allen screws slowly and carefully until it is where it should be using the Suiter book (which I own as well, despite by other failings as a star tester) as a guide.

Last night, it turned out that the whole issue was really almost a non-issue. A minor adjustment (loosening) one screw and - in a few minutes - the star test was excellent. We decided that one of the screws was set for the warmth of California where it was set and had been left a hair too tight. The cold (and it WAS cold out there) and rapid drop pinched it a tad. Loosen it not even a quarter turn, and the tests were right out of the book - excellent results.

Turn back to the Trap and M-42. Images were excellent. Out again very early this morning (my daughter got up at 3 am to get ready for me to take her to the airport to return to school - and of course she couldn't pack the night before since we were leaving at 6) and the star images were just great, all resolved down to nice, hard little balls and points of light without smears or odd shapes.

I had heard the original Borg cells could not be collimated "in the field." The new ones (assuming they all work like the 125) are easy to adjust, and not the horror show I was led to believe. My take on the 125 optics now that they have been fine tuned? Good contrast, no in focus color to my eyes, and a true apo in performance.

One final note on this 'package.' I also spent most of my time last night (both sessions and totaling about 7 hours) using the binoviewer and occasionally the Maxbright on deep sky with one of my Naglers. The binoviewer will do just fine without the barlow. (The AP binoviewer has a removable 1.3X corrector that I leave in, This corrector doesn't really intrude on your viewing. and while it can be removed, the unit is sharper with it left in place.) Remember, however, that I was using the shorter main tube I substituted for the one that comes with the normal 125 ED f/6.4 VI. If you are not going to use a binoviewer that is as in focus critical as the AP (but I feel it is the best unit you can buy) or if you don't mind using a barlow, then the standard 380 mm main tube should work just fine. The 330 mm tube I am using does require either racking out the draw tube close to its limits (which still lets it work just fine) or using the longer extension tube (part # 7509) when using a longer focal length 2" diagonal such as the Maxbright. This is really no problem at all, as the 7509 is standard equipment on the smaller 3 and 4' Borg visual packages and I prefer the shorter OTA for the binoviewing I have become addicted to. And, with the exception of the TMB OTAs, the 125 Borg in this configuration is one of the only refractors I am aware of that will let you use the AP binoviewer without using a barlow.

Why the Borg? The definition and contrast on difficult targets such as Jupiter and the full Moon was all that I could ask for in the 125. Deep sky with the binoviewer or with a Nagler was also excellent. Better than the 130 f/6 AP? No, that scope is still a step up. Did I get better planetary/lunar than than my APOmax? No, that is still my absolute favorite 5 for the planets or the Moon. Then why a 125 Borg if I own other 5" apos that will match or overmatch the Borg?

Simple answer -- at least for me. The Borg may not match the heavier 5s, but it isn't all that far behind, and has its own, unique virtues as well. And it those unique virtues that are the reason I bought it and now intend to keep it.

The 130 AP is only 15 or 16 pounds and the same length as the 125 Borg (The APOmax is about 35 and is a F/12.) But the Borg is under 10 pounds and will break down into pieces small enough to fit into a small case. But there is more to consider than just the size, weight, and length of the OTA in this equation.

The OTA is only part of the package in any refractor. The 130 AP needs a mount (the 400 GOTO or perhaps a GM-8 or GP-DX. Then you need a tripod that will hold those mounts. So, while the AP is relatively easy to set up and use, and is a great performer, it is still not a lot of fun to haul through an airport or take with on a vacation where space and weight are critical factors. (That is why Roland made, and calls, his very compact 4" apo the 'Traveler.")

Now the 125 Borg. An OTA that weighs less than 10 pounds in 'fighting trim' and breaks down into a real small package for travel. Also, the same small OTA will let you put it onto a real light weight tripod such as a Velbon 640, a carbon fiber gem that folds up to 17" and weighs 2.9 pounds !!!!!! What will it hold? 25 pounds. Then use the Giro-2 as you mount and toss in a lightweight diagonal (the Tak 1.25 prism is excellent and weighs zip) and a few eps (or even the Leica zoom if you want to take only one) and the WHOLE THING, OTA, MOUNT, DIAGONAL, TRIPOD, AND EP go into a single case that will work as carry on luggage and come in at or even less than 15 pounds -- perhaps several pounds less!

Sorry for the shouting, but given a bad back, whatever I can do to make my travel and vacations easier, and still haul a scope with me, I get excited. But why the 125 and not the smaller 100 or the 76? Easy.

Last night, we had the 100 and the 125 Borg up on either side of the Giro 2. The view of Jupiter and the Trap reminds me that a good 5 will always give you substantially better views than an equally-good 4. The Borg 125 ED lets you get that view in a package that is easier to set up and to travel with than most 4" refractors. So, am I going to toss my AP out as chopped liver. No. Am I keeping the Borg. Yep, and now you know why.

Final Thoughts:

I was very impressed by Dale and Ted and the way they were supportive and interested in following through with their products. Getting the information out of their website isn't the easiest thing to do because of the vast number of possible configurations offered by Borg. Nonetheless, Ted is quite knowledgeable and willing to explain everything. (He was also unfailingly kind and patient with my many questions, and genuinely concerned that I was buying the precise components I needed. Finally, he was right there when I had the minor problem that he and Dale worked out very, very quickly.)

Bottom line is that the 125 ED is a fine scope and unique in what it can do. It offers the viewing possible in a 5" refractor that is, by its nature, better than what you can get in a smaller refractor. It offers that view in a potential complete observing package that is smaller, lighter, and far easier to use or move than any other. A niche product? Yes, but a very real and important niche to many of us who want to set up with ease and take the best possible view and with the minimum of fuss or trouble with us whether that 'with us' is a half hour away by car or half way around the world by plane.


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