Categories See All →
- CN Reports
- User Reviews
- How to . . .
- Observing Skills
- Astronomical History
- Optical Theory
- Vision and Related Experiments
- How to Gain the Support of your Family for your Astronomical Pursuits
- Evaluation Tips
- Special Events
- The Elements
- New Articles in [!monthname!]
- Telescope Articles
- Submit a Review / Article
- Monthly Guides
- Behind the Scenes
- About Us
- Copyright ©
- Terms & Conditions
- Tiny Eyes on the Skies
- From the Editor's Desk
- What's Up . . .
- The Light Cup Journals
- Who is this Super Light Cup?
- Cloudy Nights T-Shirts
- Imaging Contest
- Small Wonders
- Previous Imaging Contest Winners
- This Month's Skies
- Mike's Corner
- The Cloudy Nights Friends and Family Discount
- Uncle Rod's Astro Blog
- Fishing for Photons
- Binocular Universe
- Article Submissions
Mini Borg 60ED as a Finder
Voice your opinion about this subject in our forums
A Review of the Mini Borg 60ED
by Fiske Miles
The finder may be the most under-rated item in the amateur astronomy toolkit. Manufacturers long ago stopped including quality finders with their telescopes. One school of thought even recommends eliminating the optical finder altogether and using only a Telrad or other 1x device. That's a shame because a good optical finder enhances any telescope, making challenging objects easy to find and providing enjoyable wide-field views unavailable in larger instruments.
|The author's Mini Borg 60 mounted on a Celestron C11 SCT with a Losmandy 65mm quick-release bracket that enables the instrument to be switched to other scopes in moments. The Borg's 4.4 degree field makes a fine complement to the primary scope, which is limited to a maximum field of about one degree.|
After years of struggling with poor or mediocre finders, I finally had enough and decided to get a good one. I chose a Mini Borg 60, a tiny and versatile refractor that goes far beyond being a good finder. In this review I'll explain why I chose the Mini Borg over vaunted 60mm offerings from Tele Vue and Takahashi, delve into the somewhat confusing details of Borg configuration, provide an analysis of the Mini 60's optical and mechanical qualities, and offer a perspective on why I believe this tiny refractor is worth its considerable price. I will also tell how you can add a Mini Borg to your observing kit for a more modest fee.
I had some important criteria for my finder. First, I wanted a right-angle, correct image (RACI) finder. Straight through finders require neck-craning contortions that challenge the flexibility of yoga masters. Right angle finders with mirror diagonals solve this problem, but reverse the view from left to right and make starhopping an exercise in frustration. Mirror-diagonal finders have probably done more to promote GoTo telescopes than the combined advertising budgets of Celestron and Meade.
The secret of the RACI finder is an Amici prism, a device that bends light 90-degrees without reversing the view thus providing a “correct” image that matches star charts. This advantage is so important that every person I observe with who has tried a RACI finder has bought one.
|Borg does not offer an Amici diagonal on its lengthy component list but does offer a T-Thread adapter (#7522) that works with the Baader Precision Amici diagonal (right) shown here with an Antares Amici diagonal. The Baader diagonal has a full 1.25-inch light path. The light path of the Antares unit (like most Amici finder diagonals) is only 0.75-inch, which causes vignetting with wide-field 1.25-inch eyepieces including the Tele Vue 24mm Panoptic. The Baader diagonal has a Zeiss, 7-layer multicoated prism. A side-by-side test of both diagonals is provided in the evaluation section below. The Wikipedia.org entry on Amici roof diagonals includes an illustration of its light path.|
Excellent optical quality was also a requirement. The ubiquitous Antares RACI finder suffers from optics that are anything but excellent. Only the center of the field can be focused and the off-axis illumination is abysmal. The Antares finder is adequate from dark-sky sites where faint stars are easy to see, but under light-polluted skies it is little more than useless. It does not provide satisfying views from any location.
Mechanical quality was an important consideration. It's no fun observing with equipment that requires constant fiddling. You spend your time concentrating on equipment instead of the night sky. I also wanted an instrument that was small and light. I use several telescopes including a Tele Vue TV-101, an 8-inch Dobsonian, and an 11-inch SCT. The finder would have to work with all of them. Bulky finders are manageable on massive equatorial mounts, but are a hassle to balance on anything else.
Most of the frequently suggested finder upgrades,” fail two or more of these criteria. For example, the Orion ST-80 offers surprisingly good optics for its modest price of $180 but weighs in at a hefty 3.6 pounds, requires a large 90mm finder bracket, and has a flimsy rack-and-pinion focuser with that greasy feel you just know will turn to concrete in cold weather.
I soon found myself considering the Takahashi FS-60C and the Tele Vue TV-60. At around $800, these cost quite a bit more than I had planned to spend —- a trend in my astronomy purchases noticed by both myself and my wife. With excellent timing, Tom Trusock published a report of both instruments on CloudyNights, confirming my assumption that both are optically and mechanically superb. But, along with solid performance both are equally solid in the weight category. The Takahashi weighs 3.7 pounds and the optical tube assembly (OTA) has a surprising diameter of 80mm. The TV-60, with the proprietary bracket required by its conical design, weighs even more.
About this time I came across a Borg 77Ach refractor on Astromart. I hadn't heard of Borg telescopes before. The name sounded like the cyborg arch-villains from StarTrek. A brief internet search turned up the Hutech Astronomical Products website, which provides a wealth of information about Borg equipment. Based in Torrance, California, Hutech is the exclusive international Borg distributor.
A Borg FAQ page on the Hutech site explains that the name comes from a combination of the Japanese words Bo-enkyo (telescope) and Do-gu (equipment) or Bo-gu, which translates as Borg. The Borg line includes refractors and astrographs organized in various system solutions with an emphasis on photo-visual performance, portability, modular design, and a wide selection of accessories. The 77Ach weighs 3.5 pounds and is based on an 80mm OTA, similar to other instruments I already rejected. But the Mini Borg series, described as versatile, ultra-compact finder/spotter scopes, was another story. The Mini 60 OTA, the largest scope in the series, which also includes 45 and 50mm instruments, tilts the scale at a svelte 450 grams or about one pound. And the slim Mini 60 OTA would fit the Losmandy 65mm quick-release bracket I already owned. Though I had never handled one, the instruments certainly looked like quality gear. I called Ted Ishikawa at Hutech and requested product brochures and a catalogue.
|Hutech Astro's Mini 60Ach evaluation unit mounted on an XT-8 dobsonian. Note the drawtube extension. Ted Ishikawa was concerned the Mini 60 would not have enough back focus for both the Baader Amici prism and a helical focuser, but it has plenty. Borg literature suggests the drawtube alone can be used for focusing. I found this approach workable but not ideal and ordered a helical focuser with my Mini 60.|
I also talked about my interest in 60mm refractors with some of my observing friends. One question they asked was did I think a 60mm scope would be that much better than a 50mm finder, considering the price? That was a good question. The truth is that I didn't have access to any of the three scopes on my short list. I was especially concerned to know if a 60mm instrument would perform adequately from my light-polluted urban backyard. I called Ted Ishikawa back and explained my dilemma. He graciously agreed to send me a Mini Borg 60Ach (achromatic) evaluation unit.
The 60Ach arrived in a few days, and I wasted no time giving it a thorough tryout in my backyard and from a convenient dark-sky site. I was impressed with its crisp views and excellent mechanical quality. It showed 9.0 mag stars from my backyard, fine for starhopping. And the Mini 60 balanced easily on all of my scopes. When I tested the 60Ach on several high-contrast subjects in daylight, however, amber and purple fringing was noticeable with a 7mm eyepiece (about 46x or 20x per inch of aperture) —- no comparison for my Tele Vue TV-101 APO.
I reasoned with myself that the wide-field performance of the 60Ach on the night sky was excellent —- more than adequate for my purpose. Then I took another look at the specs for the Borg Mini 60ED, the APO version of the 60Ach. Both objectives incorporate two elements and are fully multi-coated. But the rear element of the 60ED is made from ED glass for improved color correction. The 60ED was “only” $285 more than the Ach. And the 60ED would make an impeccable daytime spotting scope for bird watching. Borg offers a field-flattener for the Mini 60 and mounting adapters for just about every camera made. I told myself I could also use it for astrophotography and daytime digiscoping. And I thought of all the fun Tom T. had using ridiculous amounts of magnification to test the performance limits of the FS-60C and the TV-60. Did I really want to get left behind in that race? Readers, I ordered the 60ED.
Assimilating the Borg
|Unlike other telescopes, Borg scopes are ordered from an a la carte list of components. Shown here are some of the parts I ordered including A) #6260 Mini 60ED OTA; #7502 M57 to 2-inch SCT adapter; C) #7522 M57 to M36.4 adapter (T-Thread); D) #7601 M57/60 Extension Tube SS; and E) #7857 helical focuser.|
Versatility is a significant advantage of Borg telescopes. Ironically, this feature may account for their lack of popularity in the United States. Ordering a Borg isn't like ordering other telescopes. You can't call a dealer and say something like “Pete, I want to order a TV-60.” Instead, you order a la carte from a list of 219 components including optical assemblies, adapters, focusers, eyepiece holders, what have you. Hutech offers a few base packages, but I didn't find these much help. Instead, I waded through the product catalog, pestered Ted Ishikawa with lots of questions, and carefully studied the evaluation unit. Here's what I learned.
The OTA is the primary system component and includes an “optical assembly”and a drawtube that contributes to Borg's configuration flexibility. The drawtube slides in and out, adjusting the overall length of the OTA to accept almost any combination of add-on focuser, diagonal, eyepiece, or camera. It is held in place with a finely machined setscrew that can be placed on either the left or right side of the drawtube (a typically well conceived option). Each segment is threaded, and the OTA can be entirely disassembled by unthreading the individual segments.
|Shown here is the Mini Borg 60ED (#6260) which is made up of the 60mm Optical Assembly (#2260) and the Mini Drawtube(#6160). Both parts can be ordered separately. The Optical Assembly extension tube can be flipped to reposition the internal light baffle as explained in the accompanying text.|
This “erector-set” construction also contributes to Borg flexibility. For example, the 60ED can be easily installed in a finder bracket by unthreading the center assembly, inserting the two halves from either side of the bracket, and threading them back together. More significantly, it enables the scope to be configured for twice the initial drawtube adjustment. The Mini drawtube assembly only accommodates half the drawtube length. But, when combined with either 60mm optical assembly (Ach or ED) the entire drawtube can be recessed into the scope by removing the tripod adapter and reversing the optical assembly extension to reposition the light baffle. This is a useful configuration because it increases the scope's back focus range. Borg offers a short replacement extension tube (#7458, not shown here) which can be used instead of the standard extension for additional back focus and has the advantage of not reducing the instrument's aperture, which the light baffle does (slightly) when positioned immediately behind the objective. This was not an issue for my configuration as explained in the next paragraph.
|Here is my full Borg “finder” setup, the details of which are explained in the text. It's a fun combination of Japanese, German, and American components. The Baader Amici diagonal utilizes a component design approach similar to that of Borg, enabling both the nosepiece and eyepiece adapters to be interchanged. As a result, the back focus requirement of the diagonal can be reduced by connecting it directly to the OTA with a Borg #7522 adapter as shown. The Baader Click-Lock eyepiece adapter holds eyepieces in place with a quick twist and is the best eyepiece holder design I've seen.|
Focusers and other components can be easily repositioned thanks to Borg's modular design. This proved important to me because the #7857 helical focuser did not operate smoothly because of the combined weight of the Baader Precision Amici diagonal and Tele Vue 24mm Panoptic eyepiece (a little over one pound). The focuser worked adequately, but not as smoothly as I would have liked. Ted Ishikawa suggested repositioning the focuser at the front of the drawtube assembly. This seemed odd at first, but moving the focuser eliminates the weight stress (the front end optical assembly is very light) making the focuser action as smooth as one might ask. It also repositions the optical extension light baffle to near its original position so it doesn't reduce the instrument's aperture. And, it improves overall balance by positioning the heavy backend components closer to the mounting bracket.
|Borg focusers are helical in design with a focus ring similar to 35mm SLR camera lenses. I ordered a #7601 Extension tube with the #7857 focuser to ensure maximum focus travel as explained in the text and shown in the following images.|
It's a good idea to order a #7601 M57/60 Extension Tube SS with the #7857 focuser. The M57/60 designation indicates that the part has 57mm male threads on one side and 60mm female threads on the other side. Since the Mini series is built on a 60mm tube width, all M57/60 parts work with it. Smaller parts can be connected using various adapters. The reason to order a #7601 with the #7857 focuser is that the internal focuser barrel extends past the outer focuser housing on one end of its travel range. If the focuser is connected to a part with a smaller internal diameter, the focus range is limited by the obstruction. The 7601 part is required in my setup (with the focuser mounted in front) because the optical assembly light baffle would otherwise block the internal focuser barrel.
|The #7504 2-inch Eyepiece Holder SII is shown at left with a #7601 extension tube connected on the lower end. Tele Vue 2-inch diagonals and eyepieces fit this combination perfectly (right image). Note the non-marring nylon tipped setscrews in the 7504 close-up, a detail typical of Borg's commitment to quality.|
I've experimented with several options for connecting 2-inch optical components like eyepieces and diagonals. These include a #7502 M57 to 2-inch SCT adapter, a #7505 2-inch Eyepiece Holder M and a #7504 2-inch Eyepiece Holder SII (with a second 7601 Extension tube). I used the Borg SCT adapter to connect a Tele Vue SCT adapter, which accepts 2-inch eyepieces and diagonals. The #7505 and #7504/7601 options are both more compact. The #7504/7601 arrangement seems the best to me. Two-inch diagonals and eyepieces fit perfectly and the smooth inner face of the 7504 is better suited for use as a holder. The inside of the #7505 holder has the ridged light-baffling found on the inside of most Borg tubes and adapters. Two-inch components fit easily into it, but they don't slide in and out as smoothly. The setscrews in both adapters have non-marring nylon faces.
Configuring the Mini 60 for straight-through use with 2-inch eyepieces is easy, but inserting a 2-inch diagonal complicates things. If you want to use a 2-inch diagonal, I recommend getting the #7757 Helical Focuser S instead of the #7857 and replacing the Mini 60 extension tube with the shorter #7458 extension. The combination of the larger focuser and the Mini Borg drawtube doesn't allow enough backfocus for a 2-inch diagonal. It might be possible to replace the drawtube with some combination of Borg fixed extension tubes (parts 7601 – 7604), but getting the right length would be tricky.
Evaluating the Borg
I have not made side-by-side comparisons between the Mini Borg 60ED and the Takahashi FS-60C or the Tele Vue TV-60 so I can't make definitive statements about Borg performance in relation to those instruments. When I decided on the Mini 60ED, I expected its optical performance to be excellent but perhaps not equal to the Takahashi or Tele Vue. On the other hand, it easily bests all rivals in configuration flexibility and weight (being the lightest quality 60mm instrument available). After conducting some high magnification tests on the moon, I've revised my estimation of the Mini 60ED optical performance upward.
|The Mini Borg 60ED is shown mounted on my TV-101, the setup I used for testing the Borg. The 101 has an obvious aperture advantage, but the quality of the 60ED view compares favorably with that of the 101. Thanks to its correct-image, the Mini 60 is useful for starhopping even with the 101 (which has a mirror-reversed field).|
I mounted the Mini 60 on my TV-101 for testing and made side-by-side comparisons swapping eyepieces between the two instruments, swapping the Baader and Antares diagonals in and out, and reconfiguring the Mini 60 for straight-through observation (to eliminate diagonals altogether). I made multiple observations of both star fields and the moon at 60 to 85% illumination. I also made daytime comparison tests.
The eyepieces I used included a University Optics 7mm Orthoscopic, a Tele Vue 3mm Radian, and a Celestron Ultima 2x barlow. I would not have used the Radian, but I don't own a shorter focal length ortho, monocentric, or similar design. As good as they are, complex wide-field eyepiece designs are subject to detectable aberrations in the outer 20 to 25% of their fields. For example, the outer 20% of the 24mm Panoptic's field exhibits distortion which can be easily seen by positioning the full moon near the edge of the field. False color is also apparent on bright objects like the moon in the outer 20% of the field. A 25mm Tele Vue plossl in the same instrument exhibits no false color and only minor edge distortion in the outer 10% of the field.
Nagler 5 and 7mm Type 6 eyepieces do not suffer from the distortion found in the Panoptic, but false color can be seen off-axis. The color hints are subtle, not distracting or perhaps even noticeable during normal use (when concentrating on the center of the field), but they are not hard to detect when studying outer off-axis areas. The UO 7mm Ortho exhibits no detectible false color and virtually no edge distortion. Edge distortion is well-controlled in the 7mm Type 6, but still slightly more apparent than in the ortho. Like the Naglers, Radians are also subject to false color off-axis. To allow for this, I made side by side comparisons of the 3mm Radian with my 7mm Ortho and 2x barlow in both my TV-101 and Mini Borg 60ED to gauge the color contributed by the Radian.
I also removed the Baader diagonal and configured the Borg for straight-through observation to concentrate on the 60ED objective performance. Comments on the Baader performance are included below. I tested the 60ED on a 13-day old moon at 49.7x or about 21x per inch (7mm Ortho), 99.4x or about 42x per inch (7mm Ortho and 2x barlow), 116x or about 49.1x per inch (3mm Radian), and finally at 232x or about 98.2x per inch (3mm Radian with 2x Barlow). That last level is pretty absurd, even by Tom T's standards. I could not see any aberration other than the slight amount of chromatic aberration (CA) attributable to the 3mm Radian. The view at 98.2x per inch does not snap into focus as it does at saner magnifications, but is surprisingly good.
The acid test for false color is a daylight evaluation, in my opinion. Our eyes are far more sensitive to color in bright light, and false color in daylight is found in bright areas adjacent to dark objects, like bare tree branches against a white sky, where it is easily seen. When observing the moon, false color is found in the dark areas adjacent to the moon's limb or in crater shadows, where it is harder to detect. One afternoon I studied the sharp edge of a black metal base ring for a birdfeeder in front of a sunlit white shed in our backyard using the 7mm ortho and Ultima barlow. I also made comparisons with a 7mm Nagler Type 6 and the 3mm Radian. False color along the dark/light transition could be seen with both the Nagler and the Radian, but not with the ortho. An extremely thin rim of color could be detected with the ortho/barlow combination. Whether it resulted from the eyepiece, the barlow, or the 60ED objective I couldn't determine. It was so miniscule at any rate as to be a non-issue.
|Here is the test setup I used to compare the Baader Precision Amici diagonal with an Antares Amici diagonal. I added a 1.25-inch adapter to my Borg 2-inch eyepiece holder and reinstalled the Baader 1.25-inch nosepiece so I could easily swap the diagonals.|
Seeing the sharp edge of the field stop is a conspicuous difference between the Baader diagonal and a normal Amici diagonal like the Antares. Vignetting caused in wide-field 1.25-inch eyepieces by the 0.75-inch light path in normal Amici diagonals conceals the field stop in a fuzzy blur. When I compared the 24mm Panoptic view between both diagonals, though, I found the Antares field was only about 0.2 degrees narrower than the 4.4 degree field visible with the Baader. The fuzzy fieldstop edge is distracting, especially from light-polluted skies, but the field reduction is minor. Off-axis illumination with the smaller diagonal obviously falls off, though, which can be seen by positioning a star in the center of the field and moving it toward the edge. Fainter stars visible almost to the edge of the field with the Baader are lost in the smaller diagonal at around 60% from the center. This is the more serious problem caused by the undersized light path.
|One of the comparison test fields I used was around M42, shown as it appeared in a Tele Vue 24mm Panoptic. The normal Amici field is reduced by 0.2 degrees due to vignetting. The A and B stars labeled in the illustration are 8.5 and 8.9 magnitude, respectively. Both could be seen with the Baader nearly to the edge of the field (under my light-polluted skies) but were lost from view in the normal Amici at about 60% of the field probably due to a combination of lower off-axis illumination (from vignetting) and lower contrast from less effective multi-coating.|
The outer area of the field is also obviously sharper with the Baader than in the Antares diagonal. Interestingly, the Panoptic's edge distortion is not noticeable in star fields because the effect is minor on point sources like stars. (Doubtless a design issue Mr. Nagler considered.)
I could not see much difference between the two diagonals with regard to false color. At moderate to high levels of magnification, both contributed false color to the view. I would say that both Amici prisms increased the CA by about the same amount found in the Nagler Type 6 eyepieces. That is, swapping the 7mm Type 6 back and forth with the 7mm ortho (which is virtually color-free) seemed to double the apparent CA while observing the moon. This was slightly distracting but probably wouldn't be objectionable to non-purists. Certainly, the CA was far below levels commonly found in achromats. It occurred to me that the fast f-ratio of the 60ED, which has an F5.8 objective, might have increased the problem. A longer focal ratio refractor might be easier for Amici diagonals to handle.
A characteristic of Amici diagonals, which are actually roof-prims, is that a “roof prism spike” can be seen on bright stars, especially at higher magnifications. Amici prims are composed of two elements glued together. The flat surface between the two elements causes a refractive effect similar to the secondary spider in a Newtonian reflector. Instead of a cross-hair pattern, a single line is created. Interestingly, the spike was more apparent in the Baader diagonal than in the Antares. I think this resulted partially from the additional light provided by the Baader's 1.25-inch light path and partially from the Baader's superior sharpness and contrast. This last bit is counter-intuitive, but I've found that issues like CA are less apparent on lower quality binoculars (for example) because problems with focus and color-correction make the more subtle aberration hard to detect. At any rate, the roof prism spike is less apparent than secondary spider refraction. I enjoy observing with reflectors, so this issue seems unimportant to me, but refractor purists should take note.
Another advantage of the Baader diagonal is a significant improvement in contrast over the Antares diagonal —- not surprising considering the Baader's superior Zeiss multi-coating. Views of the moon with the Antares diagonal appear decidely flat in comparison with the Baader, and stars that could be seen near the moon with the Baader were invisible in the Antares diagonal.
|Borg parts feature internal ridged baffling to improve contrast as seen in the #7505 2-inch Eyepiece Holder M shown here. Their overall fit and finish quality is impressive. Equally impressive is the precision and durability Borg achieves with light-weight parts. Other manufacturers rely on massive fittings to accomplish the same goals.|
The Mini Borg scores high marks mechanically. The manufacturing quality of the instrument shows careful attention to detail. Individual components are precisely machined, impeccably finished, and have a solid feel which belies their light weight. I have noticed a few problems with the drawtube, however. It has significant play when extended. The felt buffer strips also tend to compress with use, increasing the amount of movement. Tightening the setscrew locks the tube in place, and I could not detect any collimation problems, but I still prefer to keep the drawtube retracted as far as possible. The second problem I encountered with the drawtube happened one night when I was reconfiguring the Borg for straight-through operation. The drawtube setscrew stripped out. Both the setscrew threads and female threads in the setscrew hole were damaged. I suspect the problem began a few nights earlier when it was extremely cold, possibly as a result of the screw fitting loosely due to the cold and partially because my fingers were numb. While I have frequently repositioned the drawtube, I haven't subjected it to rough treatment.
I contacted Astro Hutech about the issue, and Ted Ishikawa pointed out that the setscrew threads are very fine (i.e. delicate) and require careful handling. I'll say! I ordered a replacement setscrew (for $3). Fortunately, the female threads in the setscrew hole are still functional, though somewhat loose, and the replacement screw solved the problem for now. The drawtube also has a second setscrew hole, which is undamaged. But the external tube is not available as a separate part, and the drawtube unit itself costs $140 (not the most reasonably-priced Borg component in my opinion). Ted did not offer to repair the part, either. This is a significant difference between Borg and Tele Vue. When I had trouble with the aluminum, captured setscrew on an Everbrite diagonal, Tele Vue simply asked me to return it for repair. Returning a part to Japan for repair is not as viable as shipping a part to New York, I guess.
Borg on a Budget
Compared with what most observers expect to pay for a finder, the price of my Mini Borg 60ED setup (including the Baader diagonal and Tele Vue eyepiece) “seems” outrageous. I say seems because when considered individually, the parts aren't spectacularly expensive. The cost for the Borg parts was $751 —- the same price range as the Takahashi FS-60C and the Tele Vue TV-60. Compare the price of any of these with a premium 4-inch APO. The Tele Vue TV-101 had a street price of $2,800 when I bought mine. The newer NP-101 sells for around $3,500 now. The additional aperture makes a difference, needless to say, but at one fifth the price, the views delivered by the Mini 60ED are a bargain. The same can be said for the FS-60C and the TV-60.
At $347 the Baader Precision Amici diagonal is an eyebrow raiser. After using it for three months, and making careful comparison tests, I think it's a good value. When the price of a Tele Vue 24mm Panoptic eyepiece is added, however, my setup totals around $1,400. That's not pocket change for most of us, including me!
If you're excited about owning a Mini Borg, but can't (or won't) spend that much money, the good news is you don't have to. You can add a Mini Borg to your toolkit for a lot less.
I noticed a likely starter set in the Borg series 2004 product brochure (available from Astro Hutech) listed as Sample Configuration 2 on page 12. It includes the Mini 50Ach (#6150), an M42 helical focuser (#7842), a 1.25-inch eyepiece adapter (#7317) and two adapters (#7523 and #7525). The total price for these parts is $361. Add a 1.25-inch Amici diagonal and a 25mm plossl eyepiece and you would have an excellent finder/RFT setup (10x/4.9 degree field). You could build on this basic setup by adding additional components later.
Observing with the Borg
I have observed with the Mini 60ED for months now and rank it as my most satisfying astronomy purchase. It's combination of optical and overall mechanical excellence, compact size, and configuration flexibility truly make it a perfect finder. Whether I'm observing from my urban backyard or a dark-sky site in the country, starhopping has become nothing less than a treat. The pace of my observing has slowed down. Navigating the sky requires less effort, and I find myself spending more time along the way noticing a colorful star here, a close double there, a small clump of stars that might be an obscure cluster —- is that a faint galaxy?
I'm no longer faced with the dilemma of do I take my 4-inch RFT or a larger aperture scope? I can enjoy both rich field and high magnification views without having to set up two telescopes or even move from my observing chair. Seeing objects in their larger context, adrift among stars that might be their neighbors or might be millions of light years closer to our own modest sun, enriches the detailed but narrow view in larger telescopes. To be perfectly honest, the gem-like field provided by this tiny instrument often upstages its larger companions. More than once I have found myself studying an object and after several minutes wondered why it wasn't brighter only to realize I was observing with my “finder” and not my primary scope.
The Mini Borg 60ED is not for the financially faint-hearted, but if you're looking for the ultimate combination finder/RFT, look no further. This instrument delivers excellent optics and unparalleled configuration flexiblity in a compact, light-weight package. The extensive component list is daunting at first, but don't be discouraged —- figuring out new ways to configure the Mini Borg is part of the fun.
- Mini Borg 60ED (my setup): #6260 60ED OTA, #7522 T-Thread adapter, #7601 M57/60 Extension Tube SS, #7857 Helical Focuser: $751.00.
- Baader Precision Amici Diagonal (with 1.25-inch nosepiece and ClickLock eyepiece holder): $347.
- Tele Vue 24mm Panoptic eyepiece: $295.
- Excellent Optics
- Unparalleled configuration flexibility
- Smallest and lightest premium-quality 60mm refractor
- Daunting Borg component list is difficult to assimilate.
- Drawtube setscrew must be handled with care.