Image of the day

From the
ATWB Customer Gallery

NGC 1893

My Account

New to Astromart?

Register an account...

Need Help?

Burgess Optics TMB Designed 3.2mm and 4mm Planetary Eyepiece Review

Posted by Ed Moreno   10/09/2008 12:00AM

This is a review of the Burgess Optical TMB Designed Planetary Eyepieces in the 3.2mm and 4mm focal lengths. These eyepieces were both bought used.

I was looking for some high power eyepieces for my recently acquired Televue 101 refractor. I have tried a variety of eyepieces and eyepiece/Barlow combinations in this telescope, but none were proving really satisfactory. The goal was to get a nice 140x or so from the telescope, with maybe a bit higher power for Lunar viewing (the only place where I typically push magnifications on such small telescopes because it is bright enough that I can push up to 40x per inch of aperture and not feel that my eye is still processing much of the low contrast detail in the view).

I have to tell you that I had somewhat conflicted expectations for this eyepiece. I had recently tried a Baader Hyperion in 3.5mm Focal Length, That eyepiece was bought used, and it actually had a broken field lens, I think TOTALLY unknown to the Seller, but I detected an almost IMPERCEPTIBLE flaw in the view and when I used high powers to magnify the internals of the lens, this defect showed through. Even though this broken lens affected the contrast very slightly, my MAIN concern was that for an eyepiece with such a “Cult” following, I had higher expectations for it than for many other recent “Bargain” eyepieces. Well, this isn’t intended as a review of that eyepiece, but I was VERY disappointed that the edge of field performance was pretty miserable when used in my Televue 101. The TV 101 is a DEMANDING telescope due to its ability to show such a wide, flat field. At f/5.4, if your eyepiece isn’t quite good in off-axis performance, the TV101 will QUICKLY show it. 3.5mm Hyperion was simply horrible off axis in this scope as compared to a 7mm Nagler in a Barlow, a 5mm Nagler without Barlow, or just about ANYTHING else.

So, with all of the hype around the TMB designed Burgess Optical Planetary eyepieces, I WANTED to believe, but I approached the purchase skeptically.

WOW, was I wrong! Read on for the details.

The first purchase was the 3.2mm. Physical inspection showed the design to be somewhat nicely made. Actually, for the price point, I think that QUITE well made would be a better description. The finish on the body consists of a matte black lower barrel with a larger helical thread upper housing that acts as an adjustable light shield. At the top of this, there is an added traditional rubber fold-down eye-guard ring.

I recently tested a Meade 18mm UWA eyepiece and I HATED-HATED-HATED the bulky housing and the pitiful lens shade. That design also uses a “Twist-up” housing, but omits the rubber fold-up eye-guard ring. On the Meade the design was STIFF, BULKY, and somewhat impractical because while it shaded the eye lens from stray light quite well, it did nothing to block off axis light to the observer’s eye. It did a great job of shading the lens though, but sometimes you need your EYE shaded more than the lens.

The Burgess by comparison is EXCELLENT! While the Helical focusing threads are a bit fine requiring 3.5 turns to go from lowest to highest setting, the movement effort was low and you only required light finger pressure to make the adjustment. The lubricant used must be light because it has kind of a “Nut on Bolt” feeling. It is not really “Rough" at all, but it feels more like threads turning against one another (as it clearly is). It is not “Buttery Smooth” but for me, it worked QUITE well because I tended to use the fold-up rubber eye guard ring with only a little upward travel of the lens shade.

The printing on my example was also nicely done with etched in print and BIG, white focal length numbering, which I REALLY LIKED!!!!

So, overall, this is NOT a “Luxurious” finish as provided by Televue on the Radians for example, but I cannot fault it in any major way. It is EXTREMLY well thought out and executed in a “Toyota Camry vs. Lexus” way. All the features and functions are there, but with a bit more utilitarian package. Me? I wouldn’t buy a Lexus. That is just me. UTILITARIN WORKS FOR ME!!!! In fact, this is an eyepiece that UNLIKE the Meade S5000 Ultrawides, actually had an OBSERVER design it rather than a Glossy Brochure designer that was more worried about how it would look in advertisements.

Next was a visual inspection of the coatings and internals. Most people simply look at the coatings in a bright light. I do that too. The coatings appeared to be uniform and rich from both ends…

I also do something that many people DON’T do.. I inspect the INSIDE of eyepieces. I do this using another eyepiece to act as a strong magnifying glass. I turn the eye lens of a 20mm eyepiece down and look through the field lens, and I focus that down the barrel of the eyepiece to be inspected… By moving through a range of focus, you can see any bad imperfection or dust on the face of each element. On cemented lenses, this allows you to inspect the quality of the cementing between elements. On air-spaced designs, it lets you see how much dust was allowed to be on the lens during assembly and if there is any dust or obvious problem like a cracked or chipped element. The Burgess looked excellent. It had tiny dust levels typical of most good quality eyepieces, which is to say very little.

I proceeded to testing. For initial testing, I always start with indoor and outdoor brightly lighted and known test targets. Some of my favorite targets are printed currency ($10 Bills) and UPC bar codes. I prefer using these targets for a variety of reasons for my initial testing. The MAIN reasons are because they offer CONTROL. I can eliminate seeing and control lighting, and because I can study the target in advance using a magnifying glass, I know the ABSOLUTE DETAIL on the target that is available. I find this hard to do when testing eyepieces (and TELESCOPES for that matter!) under the stars.

I use the Televue 101 for this because as far as I can tell, it is optically just about perfect. It has a very flat field, with very little off axis aberration, and for a short focal length eyepiece like these that are INTENDED to be used with short focal length telescopes, it is a good match.

On printed money, I tried a wide variety of eyepieces and eyepiece/Barlow combinations. Now 3.2mm is a VERY unusual eyepiece focal length. In fact, one of the few telescopes that CAN exploit it well is the Televue 101 because of its quite short 540mm focal length. Becaue of this, you are kind of FORCED to use a variety of eyepiece/Barlow combinations, and it is almost IMPOSSIBLE to always MATCH the exact same exit pupil. This is ANOTHER great reason though for using BRIGHTLY LIGHTED test targets. At very small exit pupils, using a bright target to me seems to mitigate (though not ELIMINATE) any conflict that might arise due to the difference of a .1mm exit pupil difference.

Anyway, I tried a BUNCH of different combinations, including an 8mm Televue Plossl in an Ultima Barlow (an excellent combination), a 7mm Nagler (This eyepiece is extraordinaly in its sharpness and contrast when used alone, challenging my plossls) a 4mm Orthoscopic, a Meade 6.4mm Plossl in a Barlow, and a few others.

My judgment? First, I was AMAZED at how BRITHT the view was in the Burgess. In spite of the much smaller exit pupil resulting from the 3.2mm vs the 4mm effective focal length of the Televue 8mm and Barlow, the Burgess seemed equal in brightness despite the much smaller exit pupil. It seemed BRIGHRTER than the 4mm UO Ortho. It was FAR brighter than the 6.4mm Meade when used with the Barlow. The difference was STUNNING.. I had never done an optical inspection of the Meade before (it has been in my eyepiece case for a decade and I only started internal visual examinations in the last couple of years, and mostly when I think there is some problem. I never REALIZED how bad the light transmission was in the Meade 6.4 though because I had never really paid attention. But once I saw this, I was FLOORED at how much brighter the Burgess was. I tried a 12.4mm eyepiece in the Barlow against the 6.4 unbarlowed, and here the difference was noticeable, but not quite as much as with the Burgess, so that eliminated the Barlow. Even when compared to the Televue 8mm in the Barlow, the Burgess seemed JUST as bright. When I studied tiny details on the back of a $10 bill, the level of brightness seemed unnatural for such a small exit pupil. I was really amazed! How could an eyepiece with a much smaller exit pupil seem to MATCH the brightness of a Telvue 8mm in a Barlow, or be BETTER than a 4mm Orthoscopic! Both of these eyepieces should detectably brighter images at these exit pupils.

An internal examination of the 6.4mm showed that the most likely cause was the cementing between the elements. I detected a dozen tiny bubbles and imperfections in the coatings. This eyepiece has always seemed to work OK, but not great. I knew that it was not a great eyepiece and didn’t use it much, but dusted it off for this test. Now I know that it needs to be scrapped.

So, how did it do on sharpness and contrast? Superb.. Simply superb. Using a $10 bill indoors, I was able to EASILY match the 4mm and 8mm/Barlow. There was no detail that I could see in either of the others that did not show in the Burgess. In fact, the Burgess was EASIER to focus sharply than the UO. When testing eyepieces, I usually focus between 3 to 5 times to ENSURE that my focus is EXACT (another reason that I do this testing indoors on fixed targets and seated at an observer’s chair). The Burgess, in SPITE of its higher, less forgiving power, really “Snapped” to focus. In this regard, I think it was BETTER than anything else I used during testing. While I cannot say that I was able to detect any more absolute detail with the Burgess than with the Ortho or TV Plossl Barlow combination, the Burgess just seemed to make it a tiny bit EASIER to see that detail. I was impressed.. I don’t impress all THAT easily, but here was a case that really surprised me.

Next, I moved to an outdoor target. It was a UPC code on a vent pipe on a house about 100 feet away.. I use bar charts to test contrast. If there is any problem, the result is that when viewing closely spaced lines, the lines will loose a tiny bit of crispness and the white space between the closer pairs will be a bit “Greyer” than the white space between the thicker, more widely spaced pairs (Your telescope has to be almost perfect opticallly too, and NO reflector or SCT will do nearly as well, so the are not suitable for use in this kind of testing of eyepieces). But an eyepiece that fails this when used with a high quality telescope has some serious defect. I already KNEW that I would unlikely detect any problems, and I did not. On-Axis contrast performance was literally perfect.

I also use the bar charts because they make it EASY to really see the effects of pincushion distortion and edge of field aberrations. If you start with a bar chart at the center of a field and more it so that the bars are parallel to the direction of movement, as the chart gets to the edge of the field, you can literally see it “Stretch out” if there is much pincushion distortion.. Also, in the presence of off axis aberrations, these UPC labels make it EASY to see the effect on the target because you will see the contrast between the bars start to degrade. Only the BEST eyepieces and BEST wide-field telescope can maintain the same contrast at the edge of the field.

The Burgess performed quite well on this test. I did not have a Radian to make a direct comparison, though I have had Radians in the past and know them to be uncanny in their off-axis performance. The Burgess was in fact one of the best off-axis performers I have tested, coming QUITE close to the Radians. Not exact, but VERY close. I WISH I would have had a Radian handy for comparison, but I didn’t. MEMEORY says the Radian was MICROSCOPICALLY bit better.

All in all, my primary testing methods told me that the Burgess was a top quality optical performer.

Under the stars, that was indeed the case.

The eyepiece has wonderful eye relief and was one of the most comfortable planetary eyepieces I have ever used.. It was 100% as comfortable as the Radians I used to own. The 5mm and 7mm Type 6 Naglers are actually quite excellent in terms of sharpness and contrast, but for the kind of long periods that your eye is required to be at the eyepiece to eek out difficult detail, they are not as desirable due to the rather short eye relief, so the Burgess was a welcome change.

I noted no problems with internal reflections, ghosting, or scatter. The eyepiece showed a level of detail that was consistent with the best Plossls and Orthos, and Radians I have ever used. I could not match exit pupils exactly, but when using the 4mm Ortho or the 8mm/Barlow, or the 7mm Nagler and Barlow, I felt that it was actually EASIER to get exact focus in the Buregess, and that the level of crispness and brightness was exactly what I would expect from a planetary eyepiece. Again, I tend to trust my work with test charts as being more reliable for me than testing using planets because of the ever changing atmosphere and small differences in exit pupil, but there was no detail visible in any of the other eyepieces that didn’t seem just as easy to see in the Burgess despite the smaller exit pupil. As compared to the 6.4mm Meade in the Barlow, the Burgess was notably better. The Meade actually produced a fairly sharp view, but a dim one. The extra brightness of the Burgess simply made detail far easier to detect than in the Meade with the Barlow. This was NOT subtle. It was MUCH harder to focus the Meade/Barlow combination, and while with patience I was able to see most of the same detail, it seemed to have MUCH more contrast in the Burgess. This was in fact one of the BIGGEST differences I have ever seen in eyepiece testing with respect to on-axis performance. The difference was striking. And I have been using this Meade in my 6" AP because it was about as much as I could use on most nights of less than perfect seeing (I go to the 5mm Nagler when seeing permits it).

On to stars. Of course stars at the center of the field are not particularly great test targets to me.. The difference between any two eyepieces is not at all easy to see when you are comparing Airy Disk patterns. There just isn’t that much “Detail”.

What I test here for is off-axis performance. I already expected the Burgess 3.2mm to fare well, and I was not disappointed. Stars were quite crisp at the edge of the field. I did not see that they were badly distorted, however they seemed a TINY bit less crisp than I remember in the Radians, though to be fair, I never used a Radian in a Televue 101 before. But my 5mm Nagler shows stars to be quite sharp right to the edge of the field in the Televue 101, so I suspect that the Burgess has some TINY, TINY amount of off axis aberration.

Then I focused on Vega. I moved Vega to the edge of the field and here was where the ONLY really detectable and VERY, VERY, VERY minor shortcoming of this eyepiece showed itself. When Vega was placed at the very edge of the field, I could see some lateral color on the outside, but more noticeably was that extending radially toward the center from the Airy pattern (which was too bright, and with seeing not as super good as would be required to see a distinct ring pattern) was a blue spike that extended maybe 2 blur diameters from the edge of the blur. It was about twice as intense at the base as it was half way along the spike and faded quickly form there.

I repeated this test with some fainter stars in the vicinity, but on these fainter stars, this effect was not really possible to discern EXCEPT at the VERY edges of the Airy disk. This may have explained why these eyepieces did not seem QUITE as sharp at the edge of the field as I remember Radians being. Folks, I have to tell you though.. MOSTLY, these eyepieces were “Pinpoint” at the edge of the field. They were EASILY sharper than ANYTHING else I have ever used except very high quality wide-field types like Naglers, Radians (if you can call that a widefield, and my beloved 8mm Meade 4K UWA. On anything but the BIRGHTEST stars, it is hard to detect the small extra blurring caused by the lateral color. For $59, this is a REMARKABLE achievement!

I recently acquired a 4mm Burgess, and in the same battery of tests, it matched the 3.2mm Burgess on ALL targets. I actually sold the 3.2mm, but for the first time I think in astronomy, I believe that the 3.2mm would have been better on the moon despite its very small exit pupil. The 4mm was dazzling on the moon. I swear I thought that in a moment of superb seeing, the rift at the bottomed of the Alpine valley was resolved, and I WISHED that I had the 3.2mm to get the image scale. The moon is one of the few places were I sometimes benefit from exit pupils smaller than about .7mm or (.8mm in my SCTs) and when I was testing the 4mm, I really would have loved to have the 3.2mm to compare it to…

So.. I ORDERED a 3.2mm Burgess NEW!!!!! Man, I don’t EVER buy NEW stuff!!!!

And not only that, I ordered a 5mm, AND a 6mm for use in my Astro Physics 6” refractor! It has been YEARS since I thought enough of just about ANY eyepiece to order one NEW, but I respect the performance of these SO much, and the price is SOOOOOOOOOO right that I figured that for the price of a SINGLE used Radian, I could get THREE MORE Burgess TMBs!!!

And THAT, my friends, constitutes my ULTIMATE endorsement. For me to buy something NEW these days is about the highest recommendation I can POSSIBLY give it. 177 stars, plus another 12 stars for shipping… They are THAT good.