Test report 測試報告    TMB 100/800 Apo Refractor

Matt Brown (nobake@netins.net)

TMB 4" triplet refractor OTA (made in Germany)
TMB 4"
三合透鏡光學鏡筒組合 (德國製造)
I purchased a TMB100/800 recently from TMB Optical. It is the model with the Vixen tube. I couldn't justify the extra expense for the nicer tube. I purchased this scope to fill a need for a more portable, quick look scope.

The Vixen tube is very nice. It is not the quality of the upgraded tube but it is functional and looks good. It passes the wife test, she says it can stay setup in the house. My other scopes are relegated to the garage. Without the dew shield it is 28" long. The dew shield screws on and is easily removable. The focuser is a 2" rack and pinion with brass compression ring and a 1.25" adapter. It was a little stiff when I got it but was loosened by adjusting the small setscrew on the top of the focuser. The finder is an 8X50 and I consider it a nice finder, much better than the 6X30's on many scopes. The OTA has tube rings and a dovetail attached so it will fit easily on a CG5 or (I'm assuming) GP mount. I have it mounted on a CG5. It holds it adequately, however I am getting an oak tripod to stiffen things up a bit. One thing I was not expecting was the weight. It is a fairly substantial scope weighing 13 pounds. Another nice feature is two lens caps, one for the dew shield and one for the lens in the cell. Of course both can't be used at the same time. It isn't as well baffled as the more expensive tube but has three tube baffles.

Optically the scope is excellent. The test report sent with the scope states .976 Strehl, 1/5 wave P-V, and 1/40 wave RMS. The certification is rather interesting, as I haven't had a test report for any optics before. I am not a star tester so I couldn't tell if there were any discrepancies but there are no obvious reasons to argue with the numbers. There is absolutely no color at all, whether in focus or out. Every review of the TMB scopes that I have read report the same results so it is expected.

I understand the popularity of smaller apochromatic refractors now. They are a wonderful scope to take out for quick looks because they set up very quickly. Similarly, when I spend a few hours with it I am not missing a larger scope because the nice wide field views or high power planetary work is excellent as well. I haven't noticed any cool down issues and of course there is virtually no maintenance. As a visual observer who dislikes any inconveniences I consider this a nearly perfect scope. Please realize that the previous statement is purely my opinion.

I have had the scope out observing quite a few times. I find myself preferring to grab it for viewing the planets in the morning (when I am up early enough) rather than setting up the G11 and MN76. I have had them both side by side on the planets and the MN76 easily shows more and brighter detail, but the TMB100 is no slouch. I really enjoy the views in the 150X range. The red spot is easily visible along with knots in the bands and a pair of bands above the NEB. I caught the emergence of a moon from the limb of Jupiter one morning and when the MN76 first showed it I switched to the TMB100 and it also showed the emergence in just a few seconds. On Saturn, Cassini is easily visible and I have seen 3 moons.

I have looked at some deep sky objects with the TMB100. M13 is a favorite to examine with new scopes. It resolves stars all across the cluster. Again not as good as the MN76, but still quite nice for a 100mm scope. The moon is pure white and I actually believe I prefer it to the MN76 for lunar viewing. The images seem "crisper" for some reason. Maybe it is just wishful thinking so I can convince myself of the value of a $2300 investment. There is some scattered light from the moon when it is just out of the field of view, but I haven't noticed this on any other objects.

In my opinion, the TMB100 does better than the MN76 on double stars. I wonder if it doesn't have something to do with the generally mediocre seeing here in the Midwest and the ability of a smaller objective to work better under those circumstances, but that is pure speculation.

I have not compared views through similar size (or dissimilar size) competing apochromatic refractors such as Takahashi, Astro-Physics or Televue.

One concern I had with the scope is a very small mark on the inside lens that was present when I received the scope. When I first saw this I was very concerned about a possible scratch. Of course this also brings up one of the major advantages of a TMB refractor, Tom Back. I emailed Tom with the concern and arranged to meet him at Astrofest and show him the lens. He dismantled the scope, cleaned the objective and explained that the mark is a coating flaw. I also was able to talk to him for a little bit while he was looking at the objective. Tom assured me I would never notice the flaw and I agree. Getting to meet the designer/owner of the company that made your scope is something that is a great plus and realistically only available on a few brands of scopes.

There is only one negative to the scope. It is expensive. By the time a mount is purchased it is easy to have well over $2500 invested in this scope. And that is the less expensive version. Of course no one forced me to purchase it and if asked I would say it is worth it to me and would buy the same again. As I stated earlier it is almost the perfect scope for me and my observing habits (lazy and planetary). The peace of mind (or pride of ownership) also comforts me in knowing that the lens is excellent and this scope will perform as well as a 100mm can. Too often I end up wondering just how good a scope is and wind up worrying more about optical quality than the views that I am seeing.

I really enjoy using the TMB100. It is an excellent scope optically and very good mechanically. I am very satisfied with it and am quite certain I will keep this scope for a long time. The only reason I would sell it would be to upgrade to a larger apochromatic refractor, which I would like to do some day.

Eddy Kwong 的網站 雙筒鏡評介

Meade 7x50 Travelview

視場: 6.4度    戴眼鏡: 可    重量: 770克

這枝中國製平價雙筒鏡表現也算不俗。首先它手感頗佳,容易把持穩定。視距足夠長,戴眼鏡也無問題。影像質素方面:中央影像銳利度不俗,應比對手10x50 机型為佳,反差當然比高級机型低,應是單層鍍膜之故 ( 物鏡呈反光藍色)。色調亦稍偏淡黃但亦不顯著。唯一問題為視場較細、感覺稍有不足。

但此平價型號最大問題是: 包裝得似玩具!整枝望遠鏡連袋用膠套封著,要試鏡就要破壞膠殼。這是為方便在玩具反斗城上架嗎? 一枝合格有餘的廉價鏡的形像就此糟蹋掉了!


美國  SKY & TELESCOPE  雜誌 Megrez 80測試報告  

全球最著名的專業天文儀器雜誌美國Sky & Telescope(星空與望遠鏡)雜誌,2001年10月號,破天荒的刊載了由國人所研發設計的Megrez 80測試報告,這不但是國人所研發設計的望遠鏡第一次以四頁的篇幅介紹及測試於美國專業望遠鏡雜誌,且以專欄測試的標題刊登於首頁,對於景德光學研發設計團隊來說,真是莫大的鼓舞與肯定。


Sky & Telescope P.51 測試編輯 by Alan Dyer
Megrez 80望遠鏡產品定位於低價位高品質入門機種,只要用過Megrez 80望遠鏡的使用者都知道,無論任何光學系統,US.600元以下幾乎不可能找到更優異光學性能的望遠鏡了,我們測試比較了兩款知名短焦型望遠鏡,美國Celestron NexStar 80 F/5、Orion Short Tube 90 f/5.6,與9cm f/10傳統消色鏡,另外我們比較兩款超高檔APO折射鏡,Astro-physics Traveler105 與日本高橋SKY 90。

一般大家所關心的折射鏡色差問題,大家都知道F值越低,色差問題越難以克服,也就是色差越嚴重,測試結果令人驚訝,Megrez 80望遠鏡所使用的鏡片為特殊低色散材質(special dispersion),其F/6的設計,色差值竟然與9cm f/10傳統消色鏡相同,這點證明了Megrez 80優異的光學性能,而如此短焦設計,能夠輕易的裝入普通背包中,最大的優勢即是更便利的攜帶性。

高倍率測試中,使用4mm高倍目鏡(約120倍),測試行星及亮星,觀測行星時,展現出真實自然色彩,還原度及銳利度表現優異,僅在周圍有非常輕微的藍暈,亮星測試同樣還原自然原色,沒有綠色及紅色色差出現。我們也實際測試了Megrez 80望遠鏡的分解能,我們使用天琴座Epsilon 雙星及M13武仙座球狀星團來測試,測試結果也相當令人滿意,使用40x目鏡就能漂亮的將M13球狀星團的恆星分解出來,確實,Megrez 80望遠鏡再高倍率時的表現成績實在是非常亮眼。

以上為部分測試內容,限於篇幅及著作權法,我們無法將全部內容刊載於網頁上,其他內容請自行參閱Sky & Telescope 10月號, The Fleet Arcade (Fenwick Pier) 及各大書局均有售。

A Beginners Review of the 80mm Megrez F6 Refractor

by Richard Beasley (reef1969@aol.com) 

Date of Purchase: 3/23/01
Years Observing: 5
Telescopes Owned: 5

I placed an ad on Astromart wanted short tube refractor with a 2"focuser. I received a response from a guy named John Garin, he said he had an 80mm Megrez, with a 2" focuser. This is my first refractor, and I had no idea what a Megrez refractor was. I did a little research, and decided to buy. I mentioned John because when I received the scope it looked brand new, not a mark, scratch, nothing. Thanks John!

I unpacked the scope, and it's nicely built, it feels heavier than the listed 4 pounds, but I do not have a scale. The scope comes with nice tube rings, sliding dew shield, and a decent focuser. My first impression is that this is a decent little scope.

I do not yet have a mount; I was not sure what to get. After receiving the scope, I placed an order from Orion for the az3 mount, but it has yet to arrive. I mounted the Megrez to my LX 200 with a finder scope bracket, with a block of wood sandwiched between the bracket, and scope. Trust me, it's a sight! This method is not very stable, so I decided not to use the big scopes motors.

I place the 45-degree diagonal in the focuser, and pop in the supplied 25mm eyepiece. I find M42, and try to get the focuser to work; you have to get the adjustment just right. I finally figured it out with John's help. The view was wide, but there appears to be astigmatism, and the stars at the edge are arcs? I pop the 14mm Pentax XL in the focuser, the arcs are gone, but the astigmatism is still there. I decided to try my 2" Televue diagonal, now the astigmatism is gone. It appears the 45-degree diagonal induces astigmatism, and the 25mm eyepiece leaves something to be desired.

After the eyepiece and diagonal problems have been sorted out, I decided to see what this scope would do on Jupiter. Using the Televue diagonal, 14mm Pentax, and a 2x barlow, I pointed to Jupiter. The scope snaps to focus, unlike my mak/cass. The contrast at 68x is nice. I was able to see the SEB, and NEB clearly defined, the poles show a hint of shading. I don't own any short fl eyepieces due to the mak/cass having such a long focal length. I think this scope can be pushed to at least 100x on Jupiter, and maintain a good image. The scope is advertised as a semi-apo, I am not sure what that means, but its no apo. The violet ring around Jupiter is annoying to me, but I have learned to overlook it. I was only able to detect a hint of color around the crescent moon, much less than on Jupiter, I thought that was odd.

I did not buy this as a planetary scope; I bought it as a quick look scope, and to compliment to narrow fov of the mak/cass. With good eyepieces, this scope is sharp, and contrasty. Sweeping through starfields with the 22 Nagler, stars are sharp to the edge, and the fov is huge. I have found several little open clusters I would have never found with the mak. Star focus to pinpoints, and the scope produces a nice black background. I give this scope an "A" for widefield work.

I have noticed the focuser strains a little with the huge televue diagonal, and the 22 Nagler, but it works. I describe this scope as a very good example of a short tube achromat, with a nice build and finish. I will be keeping this scope for a long time.

I would like to hear from other Megrez owners, to compare notes.

Richard Beasley


Latest review of Nikon Coolpix 5700 DIgital Camera 數碼相機最新測試報告

請注意: 在美國、歐洲及澳洲甚流行的 Abbe Orthoscopics 目鏡, 即香港人所謂 J-brand Or, 日本製造, 只售 HK$300. 但彼邦卻售 澳元135 (HK$600), 貴客在港購買, 等如買一送一, 可謂超值中之超值...

...考慮, 何不即時行動 !

University Abbe Orthoscopics
If we put price aside and look only at resolving power, then these are perhaps the best eyepieces in the world!  
Available in 4 mm, 5 mm, 6 mm, 7 mm, 9 mm, 12.5 mm, 18 mm and 25 mm
  In a recent telescope test in an astronomy publication, the reviewer; a noted expert in the field, finally got around to the acid test of performance - absolute resolving power. He dug into his eyepiece collection and came up with one of his favorite resolution testers, the Orthoscopic. To test the ultimate resolution, he didn't use any $300 eyepiece with sandwiches of light robbing, resolution softening lenses, he used the classic 4-element Orthoscopic!

How can a 4-element design give absolute true color fidelity in planetary imaging while multi-element eyepieces "bleach" the color right out of the image? Often the laws of physics dictate "less is better." Yes, if you're interested in the sharpest view of a planet or lunar mountain range, then you need the University Abbe Orthoscopic.

Please do not confuse these original University Optics Orthoscopics with similar appearing oculars being sold elsewhere, or worse yet with Plossls made in China that are flooding the market.

University Optics Orthoscopics are crafted in a small shop in Japan employing a few select optical workers. University Optics personal association with the owner assure they receives only the "best of the best" out of each production lot.

Over the years, construction details have been constantly improved so that the optical elements even include the latest Multi-Coatings. The barrels are finely machined from brass and then given a satin chrome finish. 1-1/4" and threaded for filters of course!

The generous field of view varies from 42 to 45 degrees. Eye-relief is very comfortable. The aluminum eyepiece caps are non-reflective satin black. Our units are supplied with both ocular and barrel dust caps.

The best news, however, is the price! 
Item Number
Price A$

Borg Refractors: The "80 mm" Family
Part 2: Borg 76 mm F/6.6 Apochromatic Refractor
by David A. Novoselsky (dnovo@ix.netcom.com)  By courtesy of David Novoselsky

空氣污染指數達120時拍攝的太陽 Sun taken under API 120

(left to right) Borg 50 ED, 76 ED, 100 achromat and 100 ED objectives                         Solar  images taken with Borg 76ED+Solarmax40
                                                                                                                                  For details, please visit
Vincent Chan's ETX web site              

Physical Description and Background -- Borg Refractors:

The background discussion relating to the Borg 76 ED is identical to the 50ED reviewed elsewhere at this site. If you have already read that review, you may skip down to the section entitled Borg 76 ED for a review of this particular telescope.

As I found out in researching the Borg products before purchasing my 125 ED, unlike virtually any other telescope, the Borg refractors are completely modular in concept. They are 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.

I have provided a more detailed background description of the Borg refractors in my review of the Borg 125 ED available elsewhere at this site. Please see that for any additional information you may need.

The Borg 80 mm Family of Refractors:

The first 'family', which will be covered in this and related reviews, consists of a group of objective cells that all fit on the Borg standard 80 mm diameter tube set, part # 6000. The basic 80mm tube set consists of an 80mm diameter 205mm long optical tube, a draw tube holder and draw tube, the Borg 7835 Helical focuser, a long and a short extension/eyepiece holder, and an adapter. (Remembering that all things Borg are modular, the main tube may be removed and shorter tube (124mm) and slightly modified draw tube substituted for binoviewer use.)

You could simply order this basic unit and then add an objective cell. However, the slightly cheaper way to do this would be to order one of the "telescopes' themselves, and get this basic unit and an objective. In that configuration, you have the equivalent of most other 'telescopes', and need add only an eyepiece and a finder, if desired, and you are ready to go.

The Borg 76 ED:

The second member of the 80mm family can be purchased by selecting a package (part # 6077) that adds the 76mm ED doublet objective cell and a lens hood to the basic 80mm set. The current retail price is $810. The result is an f/6.6 ED doublet that weighs only 1.7 kg or 3.74 pounds. (The lens cell itself weighs 500g or more than double that of its smaller, 50ED brother.) Like all of the Borg refractors, the 76ED is completely modular, and the objective can be removed and stored for transport, with the focuser and main tube packed easily into an airline portable package.

First impression? I tested the 50ED, the 76 ED, the 100 Achro and the 100 ED at the same time. Since I was using the same main tube assembly and focuser for each member of the 80 mm family, see the review of the 50 ED for my initial comments on this 'telescope.' Suffice it to say that the build quality is very good.. The paint on the OTA and the objective cell is smooth and glossy. The finish on the focuser, draw tube, and other parts was very nice, and in distinct contrast to the Chinese refractors that, while priced much less than the Borg, are mechanically very crude and crudely finished in comparison.

Mating the 76 ED objective (the second to the left in the photo of the objectives shown in the review of this 'family') to the main optical tube takes only a few seconds, screwing it onto the end of the base unit to complete the 'telescope.' The lens hood, unlike its smaller brother, slides forward and care should be taken to pull it forward gently and grasp the cell itself when securing it to the tube.


Weighing only a skosh under four pounds, and fairly well balanced even with a lens that weighs more than twice that of the little 50ED, the 76 ED will also mount on just about anything with ease. The pictures show the 76ED mounted on the Borg single-arm AltAz mount (less than a pound) and on the Velbon 640 carbon fiber tripod (less than 3 pounds) using the Borg plastic tube ring (weighing virtually nothing and surprisingly rigid and inexpensive.)

I will review the Borg AltAz mount in a separate review, but must say here that as much as I liked it, it was about at its limit of reasonable usage with the 76ED and my FS-60C. The larger Borg 100 Achro and 100ED worked, but the mount was much more sensitive to vibration and wind with the heavier units.

If you want to use the 76 ED on an EQ mount, its short length and very light weight will let it work on just about anything. The 76 ED was very happy on the GP-DX with the SkySensor 2000, and was just as happy on a friend's lighter, CG-5 mount. I dare say that virtually any EQ mount should handle the less than 4 pound load of this scope for whatever purpose you want.

And, like its smaller 50 ED brother, the 76 ED will work fine on virtually any tripod and simple mount. The Bogen 410 Geared Head handled this unit with ease, as did the Bogen Ball Head that I normally use for a pair of light binoculars. Indeed, it is difficult to think of any mounting system that will not work well with this telescope.


Okay, true confession time again. This is, IMHO, the 'sweet spot' of the Borg 80 mm family of refractors. As nice as the 100 ED is, and I bought one to use as my ultimate 4" travel scope, the 76 ED is clearly the best buy and best performer for the price.

The 76 Achro (which I didn't test, but can extrapolate from my test of the larger 100 Achro from an optical standpoint and from a physical standpoint from the 76 ED) is better built and better corrected than the other 70 to 80 mm fast achro or so-called 'semi-apos' on the market, but suffers from the same optical limitations that dog those scopes. Poor lunar/planetary performance. The larger 100 Achro will provide better performance because of its larger aperture, albeit a bit harder to mount. The 100 ED overcomes the limitations of the Achros, and will provide the optical benefits of the 76 ED, but at a price that is more than double that of the 76 ED.

That puts the 76 ED, as I said, in the 'sweet spot.' Unlike the Borg Achros, which (as Brian Murphy found in his review of the 100 Achro and I confirmed in my tests) are limited by their non-ED optics to lower power views with some color on the Moon, planets and bright stars, the 76 ED is free of any spurious color in focus and exhibits very little out of focus. (And, for those of you who have read my reviews before, you know that I am not interested in out of focus images at all.) The 76 ED takes magnification very well and the images do not break down even when pushed very hard. Cool down is quick and, like all of the Borg refractors, it breaks down into a light, easy to move and set up, travel package.

But this sounds quite a bit like the 50ED I reviewed earlier, doesn't it? Sure, but with a very significant difference. The 50ED is limited by its very small image scale and light gathering ability. The 76 ED provides images that are much more palatable to the eye, and just as well corrected in focus and in the eyepiece, and on an image scale that allows for far more usable detail than its smaller brother.

Detail, contrast, and clarity on the Moon and Jupiter where much like the smaller 50ED, but again with an image scale that made this a much better, all around performer. And, unlike the smaller Borg, there were other scopes available to me to compare this 3" refractor to that put its performance into a perspective that is easier to understand.

The 76 ED is similar in size and aperture to the ubiquitous Chinese-made Short Tube 80 mm achromats (I own a Celestron version) and the almost equally-ubiquitous Tele Vue Pronto, my very first refractor. The 76 ED got a thorough work out against each of these scopes.

Leaving mechanical issues aside (and there is no comparison here) the ST-80 is a fine rich field performer. However, the Borg, despite its slightly longer focal length, did just as well on the basic deep sky images and, because of superior contrast and clarity, was a far better performer than the ST-80. Could I justify the extra price of the Borg if I was using it strictly as a rich field instrument? Perhaps not, although the Borg gave much nicer, cleaner, and more consistently 'round' star images and had the ability to go 'cleaner' and more easily 'into' some deep sky objects because of it clearly superior optics. However, as a purely rich field instrument that can be acquired for less than $200, the ST-80 is hard to fault.

But once you want to turn the two of these scopes on anything else, the ST-80 falls to the side without much ado as the Borg will show the Moon and the planets in fine, color free images while the ST-80 runs out of magnification very quickly and provides a marvelous, but unwanted light show very typical of simple and cheap achromatic lenses.

Things became a little tougher to call when the Tele Vue Pronto was on the other side of the Giro 2 from the Borg 76 ED. The Pronto was my very first refractor. As at least one other reviewer said recently, everyone should own a Pronto at one time or another in their observing lifetime.

The build quality of the Pronto is superb! Built like the proverbial tank, the Pronto sits well in hand with a heft that says quality and controls that are a joy to use. And, while some of late have suggested that a newly-built rival from Taiwan has the same build quality and greater aperture, and while I have not and will not review that scope, I have seen the Pronto and it so-called competitor side by side, and believe that the Pronto remains the clear winner in build quality.

The optics on the Pronto are also far more consistent than the hit or miss optical quality that has been noted as to the Taiwanese competitor in several comments on some user groups and in a recent review by a noted expert, who found SA, astigmatism, and other optical problems that would prevent me from choosing that scope over the Pronto. However, those optical problems are not present in the Borg 76 ED, and the build quality of the Borg is very close to the justly-well regarded Pronto.

The optical performance of the Pronto would not keep up with the Borg 76 ED. The Pronto exhibited some color on the limb of the Moon and on brighter stars in focus that was absent in the 76ED. The Pronto would go beyond 100X comfortably on the Moon and on some double stars (although some disagree with me on this) while the Borg 76 ED would take substantially more power and remain clear and color free.

Of course, the Borg 76 ED has the ED element the Pronto lacks, and is also has a slightly larger aperture. However, the Pronto even allowing for the case, eyepiece and diagonal it is supplied with, costs more than the 76 ED. I feel that the Borg would be a better choice than the Pronto, which now very badly needs to be updated by Al Nagler along with the Ranger as Tele Vue basic entries for customers who want a refractor.

What else is out there in this price or aperture range? The Takahashi FS-78 is superb, and in my experience, will outperform the Borg optically when pushed to its limits. However, the differences in contrast and clarity are not that great, the longer focal length fluorite Takahashi pulling ahead primarily because of its ability to accept even more magnification and provide slightly better contrast. If cost were no object, I would buy the Takahashi.

However, the Takahashi is substantially more expensive than the Borg 76 ED at a street price of $1375 and a weight of double that of the Borg. The optical performance of the two scopes is not radically different, although I would rate the Takahashi higher, but the larger, more expensive Tak will require a more substantial mount. And, as a travel scope, it will be much more difficult to transport, move, and set up than the Borg 76 ED.

Perhaps the best way to resolve the Tak/Borg 'shootout' is that the Tak remains the ultimate performer in this aperture class pending the appearance of the 80 mm TMB triplet. The Borg is a better 'buy' however, and wins the laurels if mounting and travel is the issue.


A very nice, small ED refractor. Excellent build quality and optics, a fast setup, and perhaps the best combination of performance, ease of use, and price in today's market. I recommend it wholeheartedly.

Dave Novoselsky


Forum discuss on Or eyepiece (J-brand) click here

Below is a test report of Japan Orthoscopic eyepiece by Dr Jiang Xiaojun, Beijing Observatory, Chinese Academy of Science
以下是中國科學院北京天文台姜曉軍博士對日本製 Or 型目鏡的測試報告 (2002-3-26)

I made a star test on the J-brand OR-6 with FS102 tonight. The eyepieces for
comparison are CZJ O-6 and Pentax O-6:
On-axis sharpness (from best->good) CZJ-Pentax-Jbrand
edge sharpness: Pentax-Jbrand-CZJ
contrast: CZJ-Pentax-Jbrand

overall feeling: CZJ is clearly the best in the three, while the Pentax and
J-brand is almost at the same level, when considering the price issue, J-brand
will be no doubt the best buy.


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