18 replies to this topic

[ngc6475]

I read that TMB's Monocentric eyepieces were reviewed by Gary Seronik in the most recent issue of S&T. Has anyone gotten his or her copy yet (mine hasn't arrived) and read the article?

If so, any comments?

Walter

Thread:

[Bluemeanie]

Wow, I can't remember the last time S&T did a eyepiece review. I wish they would do more of them.

[Don25]

Yes, I just got my copy and read the review....He seems to say that when comparing them to other well known "Planetary eyepiece's" that they equal or very, very SLIGHTLY outperform other planetary eyepieces such as Vernonscope Brandon's, Televue Plossls, Clave Plossls and Edmund RKE's. He says that the on-axis performance is superb, but that the off-axis performance is poor in short-focus scopes.They are also free from Ghosting or internal reflections, but that they are utility limited by narrow apparent field of view. Overall it seems if you already have very good Planetary eypiece's like the above mentioned Clave's, Tele-vue, etc. that you really aren't going to see that much difference for the cost of these TMB's. they're listed as $225 for the 4mm to 10mm focal lengths, and $ 250 for the 12mm to 16mm focal lengths. I think I'm gonna stay with my Univ. Optics Orthoscopics, and keep my money. Hope this helps. Also apparent field of view is only 32 degrees.

[Tom L]

There's no doubt that I'll stay with my UO orthos...

[Bluemeanie]

UO orthos, gotta love 'em. One of the best bargains out there.

[lighttrap]

I think I'm gonna stay with my Univ. Optics Orthoscopics, and keep my money.

Yeah! No kidding. A 32* AFOV for $250????

[Dave Mitsky]

I had a chance to view Jupiter through five of the TMB Monocentrics at a regional star party last month. The telescope, a 152mm Takahashi refractor, was outfitted with an eyepiece turret. They seemed to work well enough but I was not able to compare them to other eyepieces.

Monocentrics are intended for planetary observation, where field of view isn't a major consideration.

Dave Mitsky

[Don W]

Yep, looks like my set of Meade Research Grade Orthoscopics just went up in value.

:money: :money:

[LivingNDixie]

Basically the way I read the review, the newer TMBs are alot of money for a extremely modest improvement.

[Mike Hosea]

They were designed for people who are perfectionists about on-axis planetary performance. The flip side of a modest improvement going the other way is a modest degradation. Modest or not, some people have trouble seeing anything else. I think it's great that Thomas Back and Markus Ludes got those eyepieces designed and on the market, but I think one of the challenges for beginners in the hobby is to come to terms with the difference in subjective assessments of relative performance that you get from different sources. If I may be so bold as to claim for a moment to be objective about it, most of the time the on-axis difference between two high-quality eyepieces is very subtle even to the eyes of most experienced observers. However, there are people who enjoy "living" in that context of discriminating subtle differences, and to simplify their language to one another they have often already adjusted it so that "huge" is a subtle difference on the large side and "small" is a subtle difference on the small side. In other words, to an ordinary amateur listening in, "huge" is small and "small" is small indeed.

[Enyo]

There is a lot of discussion about the review on the TMB Yahoo group. I will not comment on it as it is there for those who who want to read it. In contrast to the S&T reveiw I find the Monocentric eyepieces provide obviously less scatter and cleaner views than my University Ortho's, TV Plossls, Radians, Nagler, or Tak ortho. While obvious, the differences are small in the overall scheme of things. I can not detect any real difference between them and my Pentax Ortho's. The TMB's are my EP's of choice for getting the last bit out since I use them in my binoviewr and only have single Pentax O's. In addition to the above mentioned eyepieces I also have eyepieces by Meade, Celestron and Clave so I don't think I have any axe to grind. Is the difference worth the cost? For me it is.

[David B]

To elaborate just a bit on the previous post re: discussion on the TMB group, apparently the specific eyepieces used in the review had some type of defect, and are not believed by members of that group to be representative of the typical TMB mono eyepiece.

[Mike Hosea]

That may be, but I have to laugh at the thought of a the TMB Yahoo group feeling the need to come up with an excuse. Well, if it's a credible claim, I'm sure Gary will do the right thing.

Personally, I thought the Supermono I bought enjoyed the expected strength of low scatter and also excellent sharpness across the field, albeit with noticeable curvature and some lateral color in my 10" f/5 Newtonian. At first the members of the TMB group protested that they saw no lateral color and no field curvature and that maybe I had a defective one, yada yada yada. But when I hooked up with another owner with the entire initial set and the same type of scope and verified the exact same properties in his scope with his TMB SuperMonos, which were checked by TMB himself, Thomas explained that there might be some lateral color in fast scopes... If he hadn't, I expect many of the people in the TMB yahoo group would never have accepted that ANYBODY saw lateral color (let alone field curvature--which is now also widely reported in fast scopes) in one of these eyepieces without the eyepiece being defective.

[Rhadamantys]

I purchased a 5mm TMB. I needed an excellent 5mm Planetary eyepiece. TV doesn't make a 5mm Plössl and 5mm Clavé are quite hard to find.

The first 5mm TMB I got wasn't very good. It had plenty of astigmatism off axis and plenty of field curvature (at f/7.7 or f/6.25). I wasn't very satisfied so I went to my dealer, exposed the problem, and was offered to select the best 5mm TMB I could find. Two more 5mm were available and both had much better performances, as off axis astigmatism was imperceptible and field curvature invisible at f/6.25 (I must point out that the perception of field curvature will depend on the age of the viewer: the older you are, the more likely you are to detect field curvature if no specific test is made). Basically, a good 5mm TMB performs very well, but I will check this as soon as I find a 5mm Clavé and will definitly pin it against a 5mm Pentax XW (Just for fun). There is (was?) obviously a quality control problem with TMB eyepieces, as other colleagues reported similar problems. That's unacceptable for such an eyepiece.

[Starman1]

I've read that the lower limits of a monocentric design is about f/6. When most companies claim that there is a lower f/limit, it is usually because the eyepieces have a harder time with the more oblique rays of a shorter focal length. And most manufacturers are "liberal" in their comments about lower f/limits (Plossls are supposed to be good to f/4, but suffer greatly at that ratio).
So, I'd put a safer lower limit for monocentrics at f/7. Since the eyepieces available are shorter focal lengths, I'd expect them to do well in telescopes of f/8 or longer (most commercial SCT's, MCT's, Cassegrains, and many refractors), but not the Dob or Wide-View refractors. And, judging from the responses, this seems to be the case.
My question: Most eyepiece designs do very well on axis (e.g.planetary viewing), so given a "planetary" scope, can we be expected to see the difference between two eyepieces with a different number of lenses if they are both well-made?
This is a rhetorical question, not designed to incur the wrath of the monocentric groupies.
But I do wonder if the monocentric debate isn't a little like the super-high-end amplifier debates, in which the quality of the expected "sound" of a given amplifier seems to be directly in proportion to its price and reputation.
I've looked through a lot of eyepieces through a lot of scopes in 41 years of viewing. My only laugh is that the monocentric eyepieces are as expensive as they are. Compare a good Orthoscopic with the Monocentrics (which should be less expensive to make), and you get the idea. After all, the Nagler 6 eyepieces are cheaper than the 4's and 5's because there is less glass. By those standards, the Monocentrics should be about $50. That they are >$200 says more about the purchasers than the eyepieces.
And if there is a QC problem with them? Well, caveat emptor.
Don

[Mike Hosea]

Pricing strategy is easy to misunderstand from the consumer's vantage point. I'd expect TMB and APM are making a profit on the operation, but these were relatively small manufacturing orders, and there are a lot of details that could impinge on how expensive it is to make a supermono compared to an Abbe ortho. In a free market, pricing is market-based, anyway. As a manufacturer, you just don't make products that you can't price for an acceptable profit, and for that matter you don't make them unless the revenue generated will be worth the lost opportunity cost on other activities. I think this is why Zeiss got out of the amateur astronomy market and projects like TMB SuperMonos and AP SuperPlanetaries (we're waiting for the UltraMonos and the UltraPlanetaries next, followed by the SuperUltraSuperMonos and the SuperUltraSuperPlanetaries ) are coming from smaller operations who are motivated at least in part by the intangible benefit of prestige in attempting to produce planetary eyepieces with the best possible performance. The price of admission isn't necessarily going to make sense when compared to the high-volume mainstream competition, especially since the type of people who sign up for the initial offerings that finance these things are often the spare-no-expense types among us.

[PJF]

I was able to borrow a TMB 6mm for a week. It was too much magnification for my 5" Synta Mak really, but 8mm not available.

Nevertheless, I found it superb on the Moon. It gave better views than a TAL 7.5mm Plossl, which is supposed to be a very high performing budget eyepiece. This is in spite of the 7.5mm being more in the realms of realistic magnification for my scope. The TMB was pin sharp edge to edge, with no flare or reflections. I found the narrow field and 'looking down a tube' presentation was actually very well suited to concentrated observing, and as such more useful than the 'wow' view offered by wider field eyepieces.

Earlier, in daylight, I was able to directly compare a TV Radian with the TMB. I thought the Radian provided a more 'pretty', 'fall in' view, but the TMB offered the best definition of fine detail and colour fidelity. The TMB clearly gave the brighter, sharper view with the most contrast.

It would be rash to draw a conclusion after such a brief period of time, but being rash I would say that an eyepiece like a TMB mono is a 'serious' tool for 'serious' observing. It's not something to impress the neighbours with, it's something to sit down and get on with the job with.

Since I haven't tried UO Orthos, I cannot comment on the issue of whether the TMBs are worth the extra over those. I'm not prone to 'product loyalty', I don't own a TMB, and I can't currently afford one. This is just my two cents to say that in my brief encounter with one, I thought it was really rather good.

[Starman1]

Ultimately, we are reduced to this: that the skies have deteriorated to the point that deep-sky observing is less common than looking at the moon and planets. I use, as evidence for this, the recent explosion in the sale of small refractors (under 8") and the introduction of eyepieces that are only appropriate for objects that can fit in very narrow fields of view.
As a deep-sky afficionado, I desire eyepieces that can be used for both so that I do not have to afford to have multiple sets of high-end eyepieces. That means a type of eyepiece that is good on Saturn, AND the Omega Nebula AND NGC2024 all at the same time. This means, apparently, that a compromise must be made from the standpoint of the planetary observer--a compromise perhaps in absolute fidelity, but not a compromise in utility.
When I try to get a newbie interested in the sky, I almost never show him the planets. It's not because I don't get a good view, or because I don't think he/she would enjoy it. But because seeing is rarely good enough for high-resolution views of the planets, and because deep sky objects can be wonderful even when seeing is mediocre, and because I want the newbie to be involved in more than just the viewing of the 10 brightest objects, I usually recommend scopes that are general-use scopes, not specialty planetary instruments. Likewise, I recommend eyepieces that fall into the same category. So I exclude Orthoscopic and Kellner and Monocentric eyepieces and extol the virtues of Plossls and the like. They may not be perfect for ALPO members, but they provide a more engaging view of the sky through a telescope. I don't want to live in a world where everything is a general-use item, but neither do I want to see all beginners give up on the deep-sky without even trying.
For one thing, instead of getting angry enough about light pollution to want to do something about it, such scope users tend to put up with it because their planetary images aren't damaged as much by the lights.
And I want us all to be angry about it so that things change for the better.
I suppose, in the final analysis, when one says this eyepiece is better than that, we should not ask "How?" but "For what use?"
Don