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4" Apochromatic Hyper Shootout

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#326 t.r.

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Posted 06 September 2008 - 05:30 PM

Used these for years in the military and now for retirement with refractors! :grin:

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#327 lineman_16735

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Posted 06 September 2008 - 08:22 PM

I've said it once and I'll say it again. The TSA is a sleeper in the 4" apo market. I have just been tickled pink with mine and for a scope junky like me to hold onto a scope for more than a year it has to be special. Great read D!
 

#328 m9x18

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Posted 06 September 2008 - 11:04 PM

Thank you, Dr. D, Farah, June and Ridwan... Excellent work, and an informative read. Aside from the test results, I learned a bit about star tests and telescope optics (contrast, under/over correction)... I wish I had the opportunity to join you guys for a weekend, what I could learn! Thank you for sharing


Right-o Pasquale! I agree. Also, it was like we were invited to one of the grandest star parties ever. What do most experienced observes tell most novices? They say go to a star party and look through different scopes. That's exactly what Daniel did. He took us to a virtual star party and through his exhaustive tests and keen observations enlightened us to what was seen through each eyepiece. Through his tenured eyes, detailed reports and highly respected opinions, we were given a tremendous glimpse into the night sky that many of us may never otherwise have.
 

#329 TxStars

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Posted 07 September 2008 - 07:02 AM

Ahh I knew that the trusty old FC-100 would com in with high marks.
Thanks for the review.
 

#330 Dave Novoselsky

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Posted 07 September 2008 - 08:41 AM

Both are killers , I keep a FS 102 forever myself , because a perfect triplet I still can buy new any time, but not a perfect doublet.


Daniel, its a shame that you did not used the Aries Safix to tune a little bit the spherical aberration of some scopes to the level of perfection :-) , I have had one time a TSA with same little issue as yours, the Aries Safix fixed it perfectly


clear skies

Markus Ludes

btw: the best doublet apo I have ever seen and used is in my biased opinion a perfect NIKON 100/1200 ED ( I owned 6 pc, but only 3 of them where perfect )


Markus, until I got one of those three perfect Nikon 100/1200 EDs out for a couple of sessions, I don't know if I'd agree with you. I do now, the Nikon is a simply incredible 4" doublet or triplet. Beautiful optic, and marvelous workmanship, Zeiss or Tak level -- Pentax level as well.

I also agree that some of the older 4" scopes, such as the FCT 100, the Nikon, the TMB, etc are 'keepers.' You can always buy current prefection, but that Nikon or the Tak FCT are long gone and cannot be replaced.

Now, what the heck is an Aries Safix, and where does one buy one if one wants one? Dave
 

#331 Dave Novoselsky

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Posted 07 September 2008 - 08:47 AM

Hi Bill,

greatly appreciated :bow:

Ridwan,

We just got done with the 4" scopes and now you wonna do 5" scopes, you must be crazy :lol: OK, there are less 5's than 4's to compare. :grin:

To Dave N. it was a great honor to speak to you on the phone this morning. :bow:


Dan, the 'honor' was all mine. By the way, if you are up for it, I have a heck of a variety of 5" refractors, current and 'vintage' -- and in one case, almost unique (the famed APOMax.) TMBs, APMs, the 'perfect 5'AP (130 f/8.35, Tom Back 'vetted') current TMB 130SS, etc. Also have the APM answer to the old AP Superplanetary, the APM 130 f/9.25. Want to set up Shoot Out round II? Dave
 

#332 Dave Novoselsky

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Posted 07 September 2008 - 09:20 AM

NOT A BASH, BUT HONEST APPRAISAL

This part of Daniel's review brought out something I was trying to say before but had some objections raised when I said so, the critical issue of QC. Here is a section taken from Dr. D's excellent study of the 4" APOs:

"WILLIAM OPTICS FLT110-TEC vs. WILLIAM OPTICS FLT110-TMB

Now this would be an interesting comparison. Once again, the FLT110-TMB is an air spaced triplet, designed by TMB, but the optics are by William Optics. I had second thoughts about how I was going to present this particular refractor because there were four problems right from the go. I think people should know that I wasn’t going to share this at first but read on.

The first problem occurred when my crew and I first examined the optic on the William Optics FLT110-TMB. I will try and post photos. It’s not at all unusual to see a little bit of dust inside of the inner optic when a refractor is new, but this optic was nothing like that. The entire inner optic was caked with dust as if it had literally been sitting on an optical bench for weeks on end and was just put into the OTA. I asked the guys to look at it and they were stunned at how caked the dust was.

The second problem was the 2” to 1.25” visual adapter that came with the OTA. There was so much slop when it was placed in the focuser, we could actually jiggle it inside. Although we didn;t use it, we still checked it. Understand that William Optics has a very smart and unique tapered design on the barrels of their adapters, but there was still something wrong here. The third issue was the focuser, which kept slipping back when the tube was pointed upwards. Whenever we tightened the tension screw, it would prevent it from slipping, but would not allow us to adjust focus upward. I realize that there are some other screws which require some tools to adjust it, but I have to ask myself, for a $2800 OTA, why wasn’t this already done at the factory and what about all the other inconsistencies?

The next and worst problem of them all was the optic itself. It had been cooling for three hours while we evaluated the other refractors. There was so much spherical aberration outside of focus, it stayed all night long. When the scope was pointed at Saturn, we could see a nasty glow around the planet and something was surely wrong and it wasn’t the dust but more so, the severe aberrations in the star test. The in-focus star test revealed a very tiny airy disc with lots of scattered light all around it. This is what happens to the airy disc when alot of the light is not concentrated in it. This was a case of major spherical aberration. I decided to notify William Optics about the problems.

I wanted to give them a chance to fix the issues because I felt it was the right thing to do before presenting this review and I even told them I was using it for a review. After explaining the problems with William Optics, I was told that I would receive a new and proper OTA that would be inspected. We finally got the second unit in for testing and inspected it. The first thing I checked for was the dust inside and once again, it was caked with it, just like the first one but in various other parts of the glass inside. I'll post pictures of this one too. The new 2” to 1.25” adapter fit better though and the focuser was adjusted properly but then came the worst. We set the scope out to cool for two full hours and once again, it had a severe amount of under-correction, so much in fact, that the images were very soft at higher magnifications of around 180x to 200x and I could see that nasty glow around Saturn again. At this point, it was like bringing
a pocket knife to a gun fight when comparing it to the FLT110-TEC. It’s quite possible that the spacing of the optics was the culprit. I brought this issue up with William Yang in New York at the North Eastern Astronomical Forum, better known as NEAF. He explained that improper spacing of the elements was most likely the cause.

I’m not here to bash anyone, but I gave William Optics the opportunity to replace the first scope and even said it was for my review, and in my opinion, they were given a fair opportunity to correct it. I will let you now that out of every scope that was tested in this review, the FLT110-TMB was the least favorable. The optics in both FLT110-TMB’s were unacceptable and should never have even left the factory this way, especially at $2800. I love the fantastic TEC model we tested though, which sadly is no longer available.

We still have the FLT110-TEC in 1st place , the FSQ, TV101, NP101 in 2nd place, the Vixen 103, 100ED, Orion 100ED in 3rd place, TV102IS in 4th place, Antares in 5th place and the FLT110-TMB in last place."

Now this is simply not acceptable from ANY manufacturer, let alone, as Dan points out, for a scope in this price range. It does not matter how well a scope is designed, or what glass it uses -- FPL 51, 53 or Unobtanium -- if the final assembly is this sloppy. And how the heck can you claim even minimal QC if something this obvious gets out? Next, isn't it a sign of indifference or plain contempt for the intelligence of the consumer base when a REVIEW SCOPE and a second go out in this condition?

WO, AT, and several other companies purchase optics from one or more manufacturers outside their own plants, including from the one source that makes the optic in question here. Vic at Stellarvue would NEVER have let one slip through his QC in this condition, nor would Mike at AT here in the US, if one considers Norman Oklahoma civilization (sorry Mike, just kidding.)

Now I do not question WO's ability to put together a superb scope, as the other WO scope in this shoot out established, nor do I question that they can pick fine opticians to design and build a scope, including Tom and Yuri at TEC. But all the marketing in the world will not replace QC. Letting a scope go out in this condition also evidences a disregard for the observing community.

I think some of the new WO designs are just great, the new 98 carbon FLT cleary cutting edge, well priced, and quit attractive. But until these QC issues are resolved, and reported in tests like Daniels and in several other instances I have seen, there will always be a question in my mind. That is now even greater as I understand from several sources in the industry that WO intends to close down its US presence and maintain sales and, most importantly, QC from Taiwan.

Dave
 

#333 Eddgie

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Posted 07 September 2008 - 10:53 AM

Yes, this to me is what is lacking in most of these reviews.

Use of these kinds of targets is the STANDARD for Camera magazines and many Japanese specialty magizines.

I cancelled my subscriptions to Sky and Telescope and Astronomy because I felt like I was getting astro-news faster on the web, and the ONE area they COULD have contributed real value (equipment evaluations) was never adderessed to the level that I wanted to see.

They never did comparisons, they never published independent optical evaluations. In the end, their reviews were simply too subjective (as I believe this one was) to have a high reliablility factor.

And to me, I have become far more interested in off-axis performance.

Now to be fair? I LIKE to write reviews myself, and I do it all the time.

And when I evaluate optics, I DO use a star test.

But when I want to COMPARE optical performance, I use resolution and contrast test targets. These targets make it FAR less subjective than looking at something like Jupiter.

And the targets allow for off axis comparison.

I don't want to discount the work the reviewers did because I think that subjective evaluation IS valid.. I BELIEVE that it is possible to tell an outstanding 4" telescope from a not so great one when viewing Jupiter. But when the optical quality is very close, small differences in exit pupil can destroy the subjective comparison.

For this reason, to me, to do a really exaustive comparison, you have to be faultless in your matching of exit pupil, and you need a stationary, and you need a stable and known target.

Like I say, I am not surprised by their ranking though. I would have expected the Taks and Televues to finish high. Where I have seen optical bench test results, these scopes are almost always tested as being the best.

But to put the TV101 behind a 110mm scope in a 4" telescope test is clearly to me unfair.

In fact, if the Tak BEAT it, that would indicate that something was seriously WRONG with the WO. It SHOULD have beat the Tak if the quality was as good. The fact that it only TIED the Tak tells me that it was not up to the quality standards of the Tak.

Why not compare a Televue NP 127 to the WO 110? Again, this represents about a 17% improvement in light gathering! Would THAT be fair??? I think not! But this represents a 25% light gain over the 110mm scope, which has 17% light gain over the other 4" scopes in the field. No, of course not..

My big problem here is that the EYE is being treated differenty here when the scopes are used at different magnifications or when the inherent brightness and resolution is different (Line resolution is a function of aperture and not quality).

So, I enjoyed reading the test, but I do still challange the testing methods.

All that being said, my bet was that based on bench testing I have seen done in Germany and Japan, I would have expected the Televues and Taks to tie for first place or perhaps take 1st and 2nd place honors. To me, the 110mm scope have a hugely unfair advangate simply by virtue of the fact that it provided a 17% brighter image and the DETECTOR in this case (the human eye) is GREATLY influenced by a 17% brightness factor on planets.

And my concern about not matching magnifications EXACTLY was for the exact same reason. If the exit pupil differes by as much as .05mm on Jupiter, the results to me are inconclusive.

And I was really disappinted by a lack of off-axis performance evaluations. To me, low power viewing characterists are JUST as important as on-axis performance (more for me since I tend to use my small refractors as COMPLIMENTARY to my larger deep sky and planetary telescopes).

For all the "Hype" about the Hyper Shootout, It simply confirmed what I already knew.. Tak and Televue make some of the best optics you can buy. But I learnd that a long time ago by Looking at Rohrs tests, and tests coming out of Japan...

Regards.
 

#334 Eddgie

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Posted 07 September 2008 - 11:07 AM

Yes, you do what I do. I find that it is FAR more repeatable and far more sensitive than using astronomical targets.

I can EASLY see the differences between two telescope using printed media. It is MUCH easier to differentate a good scope from an outstanding telescope this way.

I use this all the time even when comparing telescopes of different sizes. As I mentioned earlier, I compared an 80mm ED scope to a much larger achromat, and without DOUBT, the small ED scope was far superrior.

But when I tested on PLANETS, the bigger scope did well. It seemed to MATCH the smaller scope (it SHOULD have done better though, and that was why I tested it). The thing is though, the extra BRIGTNESS of the larger scope let my eye work better.

But when I tested them in controlled conditions, it was CRYSTAL clear that the smaller scope was MUCH higher quality. On the test target, I was resolveing more detail in the smaller scope and the contrast was better in the smaller scope...

So, that is why I learned that if you ARE using astronomical targets, you have to match apertures and exit pupils EXACTLY..

With a telsecope like the TV 101, this gets very hard. There is not enough granularity in available eyepieces. To me, the only way to do it fairly would be to use a couple of Nagler (or other high quality) zoom lenses. This would allow you to use the EXACT same eyepice to make the comparisons, which would eliminate as many variables as possible (eyepiece tone, exit pupil, eyepice quality).

But even WITH all of this, when you use a planet, you inflict HUGE variablity. Seeing conditions, alone can change the view from moment unless seeing is ABSOLUTLY perfect. Even the position in the sky and the angle of incidence of the target through the earths atmosphere can influence the outcome.

For making A/B comparisons, Test targets are the only way to go... I just don't know why most amateurs haven't discovered this long ago.

Regards.
 

#335 andydj5xp

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Posted 07 September 2008 - 11:12 AM

.....
Now this is simply not acceptable from ANY manufacturer, let alone, as Dan points out, for a scope in this price range. It does not matter how well a scope is designed, or what glass it uses -- FPL 51, 53 or Unobtanium -- if the final assembly is this sloppy. And how the heck can you claim even minimal QC if something this obvious gets out? Next, isn't it a sign of indifference or plain contempt for the intelligence of the consumer base when a REVIEW SCOPE and a second go out in this condition?
.....
Dave


Dave,

I vividly remember the many reviews you were publishing here on CN in the years 2001 and following. Mainly your reviews about the high quality TMB scopes triggered me to get my 115/805 from Markus in march 2003. See my review on CN

here

It was a very nice scope and I've been very grateful to you for those informative reviews and also to Markus Ludes for this high quality refractor.

Reading almost every review about these scopes later I'm of the opinion that the trouble did start when - for whatever reasons - the partnership of Thomas Back and Markus ended. With the advent of scopes "designed by T. Back" the reputation of the up to then "TMB" scopes - better would have been "TMB/APM"-scopes - automatically was transfered to the new line. But this line was quite another animal and - according to the many reports later - not of the same outstanding quality as the products from the cooperation of the russian optics manufacturers, Markus Ludes and Tom Back.

Since Markus as a vendor could get into problems mentioning these facts I'm doing it because he deserves it. BTW, I'm currently not a customer of Markus and have no other intention than to recall this history.

Andreas
 

#336 Daniel Mounsey

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Posted 07 September 2008 - 01:01 PM

I''ve been away from the forum and just got busy with something again

Markus,

Thanks for the kind comments and constructive feedback, I will respond with more detail

Ed,

Thanks very much for the comments regarding exit pupil which I intentionally omitted from the review. I am not at all offended and very much appreciate your constructive feedback. Please allow me an opportunity to respond when I get a moment so we can discuss it.

Dave N.
Thanks again and to everyone for the overwhelming response, I am deeply honored. Farah, Ridwan, June and the gang were also what made the review possible, not just me. Be back shortly to reply to some very interesting topics :)
 

#337 Pasquale

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Posted 07 September 2008 - 01:05 PM

"...But even WITH all of this, when you use a planet, you inflict HUGE variablity. Seeing conditions, alone can change the view from moment unless seeing is ABSOLUTLY perfect. Even the position in the sky and the angle of incidence of the target through the earths atmosphere can influence the outcome.

For making A/B comparisons, Test targets are the only way to go... I just don't know why most amateurs haven't discovered this long ago."

Hi Eddgie, and anyone else who can clue me in!

I'm fairly green in the technical aspects of this hobby, I primarily look through my scopes at stuff overhead and while away the hours. But, my curiosity toward the technical side of this hobby is forming... As a result, my questions are for my learning and understanding.

I understand how a sterile lab environment with an inferometer and other testing procedures can identify the actual performance of an optic. It takes the variables of fluctuating field conditions out of the equation. My question is: do different optical systems perform differently when you include seeing conditions? Do some telescopes perform better with varying conditions, or do they all perform the same with identical / similar seeing conditions? If the answer is yes (I don't know the answer, that's why I'm asking), then wouldn't a test under actual conditions be more representative for the end user of how the telescope will perform for them? Thanks in advance for explaining this to me!
 

#338 Eddgie

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Posted 07 September 2008 - 04:57 PM

In general, my own experience is that if the apertures are similar, the effects of seeing will be similar.

The problem with seeing though is that it changes CONSTANTLY. Unless your seeing is literally PERFECT (.00" Scintillation), then you don't know if it was .03" when you were looking though one scope and .05" when looking through the other scope. IT is CONSTANTLY varying form MOST scopes other than Hubble and other telescopes above the atmosphere.

And the reason that test charts or targets work so well is because first of all, they are CHEAP.. Mine cost a dollar each.. LOL. So you don't NEED a lab to compare two telesecopes. But a good test chart would be the best if you wanted to get the most accurate result. They have special patterns that can quickly show how good one telescope does vs another.

So, using charts is about the most effective way and amateur can test and get a really accurate comparions.

Lacking charts, a target with a variety of different patterns and shadings is the next best thing.

Next time you have a dollar (I know, we all seem to be moving money through the astro-equipment market) take out a 20mm Plossl and use it as a magnifying glass and LOOK at the back of a crisp Fiver. You will be AMAZED at the amount of really incredible detail there is printed on modern currency. In particular, look at Abe's face on the back of the $5. You can actually see the freaking BUTTONS on his VEST!

Aim a few telescopes set up side by side and aim it at one of these and you will be shocked at how pronounced the differences can be. Just pan around the bill looking at different features.

Generally what you will find is that there will be tiny features or details that are sometimes dectable with one scope that aren't QUITE visible in the other. There is a wealth of line spacing, low contrast, and high contrast detail on most printed money..

Also, because you can do this under brighter conditions, your eye is stopped down (the pupil is constricted) which SHARPENS your vision.

With all the interest on telescopes I am surprised that the big telescope dealers haven't started selling a special chart.

But if you ever PRICE them, you find out that they typically sell for around $200.... Ouch!

But they sell for that much becuse short of true optical bench equipment, they are about the best way available to do testing.

I enjoyed the review actually, because it did kind of confirm what I belive to be true.. Good quality IS visible at the eyepiece. A telescope with really excellent quality SHOULD be able to stand out.

But when quality is near perfection (as in the Tak, TV, Ziess, AP, and a few others) it becomes MUCH harder to actually see these differences on astronomical targets and it puts pressure on the testers to be as careful as possible to eilminate all variables.

Not at all surprised that the WO scopes were matched or beat by smaller scopes though. I have suspected that the quality of these scopes varies quite a bit. Perhaps from Strehl .9 to .96. The only quality test I saw on one of these (Rohrs) put it at .91. Hmmm.. That would mean that with a Strehl of .91, it should perform similarly to a PERFECT telescope 90% of the aperture... WOW.. It DID! It was a bit better than the Teleuve 101!

See, it is all connected together...

(Note... You won't actually find that there is a direct relationship between Strehl and the performance of a smaller aperture. I am not saying that in absolute terms that a 5" telescope with .85 strell will perform exactly as a telescope that is only 85% the aperture. The human eye would still favor the larger scope becasue of the added image brightness on planets.

But in real life, the Strehl method of subtracting the Strehl from the aperture doesn't do bad job of predicitng the performance on test charts (and consequencly on real astronomical targets).

I mean you guys deserve a big round of appause.

And I BELIEVE your outcome... More or less.

In the shootout, I would have expected the Tak and Televues to finish neck and neck.. In my mind,they DID because the 110mm scopes had a VERY big aperture (ie, image brighness) advantage.

Wait until you start doing the comparisons with $5 bills though..

And with the printed material, judging off axis performance is where you often see the MOST difference between the ED scopes and the premium scopes.

And this.. I might be beating you guys up a LITTLE unfairly. See, I was in the market about 6 months ago for a new 4". I don't think TINY differences in color correction really mean that much in terms of absolute visual performacne. Bit differences in design DO greatl affect off-axis performace.

I passed on a Chinese f/7 ED scope becasue no one (including Stellervue) could assure me that they would be outstanding off-axis performers..

Because of this, I decided to bit the bullet and pay more for a used Televue 101. But I always wondered if I had made a mistake and could have picked up a new f/7 ED scope as a widefield scope.

I was hoping that the Hypershootout would do more to compare the overall sharpness of the scope. I rarely use my 4" as a planetary scope because well, in my own experience, 4" telescopes don't make all that great of planetary scopes. MN66 us a better planetary scope.

But NOTHING beats small refractors for wide field observing. They can fully illuminate a 3 degree to a 4.5 degree field (TV 101) and show it much sharper at the edges than any reflector can. But between them, some are clearly better than others. The superb Celestron 80ED scope I had was amaging in terms of contrast, but it fell apart with th the 31mm Nagler in it.. Edge of field was streaky... SO, I sold it.

Ny recommendations are to include test charts in the future, and focus as much on off-axis performance as on-axis performance. Use a single zoom to as closly as possible match magnification (exit pupil is what you are REALLY matching), and give a more balanced assessment that includes off axis behaviors.

Man I WISH I could participate in one of these shootouts.. I have to do it one or two scopes at a time.. Bummer...

Looking forward to your next test!
 

#339 Daniel Mounsey

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Posted 07 September 2008 - 07:22 PM

Daniel,


How comes that 2 scopes with perfect startest, one is a doublet with little chromatical aberration and the other one, a triplet with virtual no chromatical aberation has the same visuel contrast ?
Due better glas or better coating in the triplet ? Could be , but is here not the case ,NO !

The perfect doublet has the better contrast from using only 2 lenses due less scatter and reflections , you can see that on the optical bench.


I think you are right. As you well know, there are so many possible variables here, so I am sometimes a bit aprehensive to state why, but I think your point is strongly considered. I have learned that the more I found out when evaluating telescopes, the more questions I discover that need answering. I have also learned that the more discoveries I make, the more I realize how little I actually know. I throw in the towel, you win. I know you are very particular when it comes to optics. You are also very blunt and to the point whenever we hang out or talk, and I like that.


Daniel, its a shame that you did not used the Aries Safix to tune a little bit the spherical aberration of some scopes to the level of perfection :-) , I have had one time a TSA with same little issue as yours, the Aries Safix fixed it perfectly

So maybe in your next review you play a little with this tool , just a friendly recommentation

Keep going such wonderfull work

clear skies

Markus Ludes



Markus,

I considered the Safix and I had the two you gave me at one point. But I would rather the telescopes optics do the right thing first, so I don;t have to introduce any more elements into the optical path. If the refractor is already well corrected, then no corrector is needed but I think Ridwan would of enjoyed having some fun with the Safix since he literally spends entire evenings just star testing. He loves learning about optics and loves star testing. He also loves viewing planets all night long too.

btw: the best doublet apo I have ever seen and used is in my biased opinion a perfect NIKON 100/1200 ED ( I owned 6 pc, but only 3 of them where perfect )

:lol:

Honest to goodness, I never forgot, even to this day about this scope. I remember asking you what the best 4" refractor you ever tested was and this was it. Sadly they are enormously expensive and nearly impossible to acquire, but I'll tell you what, if you could ever get your hands on that unit again, I'll ask Tamiji to let me barrow that TSA unit and I'll bet you anything, it will give that Nikon a dead serious run for the money. His 4" is that good.

It's not about aperture, it's about the experience of actually witnessing two of the greatest optics at the cutting edge of optical performance seeing light bend to a single point! It just astounds me! :grin:
 

#340 Daniel Mounsey

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Posted 07 September 2008 - 07:48 PM

Dear Daniel,
Thank you very much for your utterly comprehensive, informative, honest and, last but not least, courageous ;.) review, which I have been waiting for since you had announced it here.
One additional question: You may also have evaluated some of the legendary short-focus Fluorite triplet apochromats such as the Zeiss APQ-100/640 or the Takahashi FCT-100/640 when they were still available. How would you judge these from your memory (in approximate comparison with the ones you've just described)?
Best greetings: Chris


I have so wanted to take a closer look at these two beautiful instrumenst but I have not tested either yet, but I appreciate the inquiry. :smirk:
 

#341 Daniel Mounsey

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Posted 07 September 2008 - 07:56 PM

Charlie, you comment regarding tube currents are important to consider, depending on your temp drop. Our temp drops from where we usually view are not that bad, so we don't endure as much trouble in this case. I have had a few challenges with reflectors because just a 2 deg. F. difference can easily reak havoc with them.
 

#342 Daniel Mounsey

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Posted 07 September 2008 - 07:59 PM


Interesting thought. I am fortunate enough to own both of the two scopes you mention, the FCT 100 and the Zeiss 100/640. Now that mosquito season is about over, and as I have several of the modern 4s Dan tested, I'll try to get you an answer sometime in the next couple months. Dan, if you are planning on coming out in my direction in the near future maybe we should get together and run some comparisons. Dave


Dave,

I am seriously considering this. I could air a couple of packages out your way and we could spend some time viewing and testing since you have so many great scopes.
 

#343 Daniel Mounsey

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Posted 07 September 2008 - 08:04 PM

Hi Daniel,

Outstanding review. You brought out some great points on evaluating optics. I was wondering if you could make any further comments on the TMB 115 you looked through and if you have had a chance to look through other samples.

Thanks,

Alan


Hi Alan,

No I have not tested any other one. On a more critical level, I noticed a bit more light scatter around planets. Zones have a differnt look about them in the star test. Have a look at some of these samples by Markus Ludes on star testing. Note that in some cases you need to use a wratten #56 or #58 green or #15 yellow .
 

#344 Daniel Mounsey

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Posted 07 September 2008 - 08:10 PM

Harvey,

I really wished I had the 105 you spoke of during the tests, but since I could not A,B them, I could not include it. After Darren returned it, I struggled to get it back and failed. I know it would have been up there with the best for sure. It snapped in incredibly! :(
 

#345 Daniel Mounsey

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Posted 07 September 2008 - 08:16 PM

Excellent review Daniel!

Is it TMB 102 not TMB 105?
I've never heard of TMB102 (I know 100/800 and 105/650).

Is it a new model or very old model?


BTW, Jared, I'm glad you like your FLT110-TEC. I loved our test unit.

DH,
Dave N. could probably answer this question better. I'm quite sure the one I tested at Darren's that night was a 105 but I'm pretty sure the 102 is no longer available, someone please correct me if I am wrong about this. Dave's like a TMB historian and was there with Thomas Back when it all happened. Dave knew Back pretty well.


BTW, please forgive all these responses. I'm trying to reply to all questions or comments in order, Sorry!.
 

#346 Dave Novoselsky

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Posted 07 September 2008 - 09:24 PM

We'll talk about it. May be feasible. Dave
 

#347 Dave Novoselsky

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Posted 07 September 2008 - 09:28 PM

Daniel,



btw: the best doublet apo I have ever seen and used is in my biased opinion a perfect NIKON 100/1200 ED ( I owned 6 pc, but only 3 of them where perfect )

:lol:

Honest to goodness, I never forgot, even to this day about this scope. I remember asking you what the best 4" refractor you ever tested was and this was it. Sadly they are enormously expensive and nearly impossible to acquire, but I'll tell you what, if you could ever get your hands on that unit again, I'll ask Tamiji to let me barrow that TSA unit and I'll bet you anything, it will give that Nikon a dead serious run for the money. His 4" is that good.

It's not about aperture, it's about the experience of actually witnessing two of the greatest optics at the cutting edge of optical performance seeing light bend to a single point! It just astounds me! :grin:


One of the perfect Nikon 100.f12s Markus was talking about is here at Casa Novo. It would be a LOOOONNNG package to ship by air, but we should talk about that. Dave
 

#348 Dave Novoselsky

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Posted 07 September 2008 - 09:40 PM

Question, Dan. The FSQs you tested, were they the older flourite models or the newer, shorter ED quads? I had one of the older ones and it was quite good visually, especially with the extender Q attached. I just got an ED version and the new extender ED from Art. Haven't had that rig out yet -- was planning on it but cloudy tonight here -- but maybe I missed it in your report but couldn't tell which version you used.

Any thought on the newer 106 vs the original? Have you tried the new one yet? Dave
 

#349 Daniel Mounsey

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Posted 07 September 2008 - 10:37 PM


First, to include a 110mm telescope in a 4" refractor competition is not at all proper. There reason is that at the same magnifications, the 110mm scope is going to have a much much larger exit pupil.. I do the math on this all the time and you can too. Even small differences in magnification of two 102mm telescopes can greatly influence the area that the light pencil exiting the eyepiece influences the receptors on the retina. A difference for exampe of 15x in two 4" telescope is sufficient to completly destroy any direct comparisons.



Hi Ed,

OK, now I can respond to your query.

I agree with you up to a certain point. The 110's and 115 were intentionally added to show observers that even aperture doesn't always win out. I included discussions on exit pupils and how it may effect our perception of contrast and decided to omit it because I've learned a few things in the past regarding the topic. One, is if the review tends to get a bit too technical; it's doesn't attract as broad an audience and people easily tend to get side tracked on the subject instead of focusing on the actual topic the review was intended for. For observers like yourself and many others, the exit pupil subject is easily understood and I don't want to imply that people can't absorb the information, but I like simlicity. The next issue is that there have been countless discussions here on CN regarding exit pupil. If you go back and read the review you may recall this quote......

"The FLT110-TEC has a bit more light grasp than the other scopes but there’s a twist to this, so hang tight." end quote

That twist was the TSA102 and the TMB102. This sentence was placed in the review for exactly the reasons you raised because I know how people start getting into exit pupils. Another thing That I hope you have not overlooked is the airy disc. Regardless of the magnifications/exit pupils used, that does not necessarily detract from the fact that the airy disc has light scattered around it. There is not an exact rule or fixed magnification that determines this. For that reason, I also included this next statement from the review and I quote.......

"I personally prefer not to state how bright a star should be or what magnification you should use during the star test, there are too many variables involved here"



Now the exit pupil issue applies even when apertures are identical. Here the need to match the magnificaiton is EXTREMELY important.


Not necessarily and we all easily proved this. If I alter magnifications slightly higher or lower than the other telescope, that doesn't prevent me from seeing the light scatter around the airy disc or the planet when comparing one refractor to the other.



In order to FAILRY test two telescopes side by side, the eyepieces have to provide almost the EXACT same exit pupil. To say that this telescope had "more contrast" because the sky looked blacker is HIGHLY subject to influence of the sizes of the exit pupil.


Not necessarily either. This is a quote regarding contrast......

"I would describe contrast as a striking dissimilarity in pigmentation between features. Pretend we have two telescopes of equal aperture. Should we assume that because one telescope yields a darker background, that automatically means it has higher contrast? In my opinion no. Assuming both telescopes are of equal aperture, it’s quite possible that one instrument may not be transmitting as much light at the eyepiece for whatever the reason and you could mistakenly interpret that to mean it has higher contrast. A better way to test for contrast is to point both telescopes a star cluster for example and observe how the fainter stars appear in each instrument. If one telescope is revealing the faintest stars just as brightly as the other instrument and it still yields a darker background, then it’s probably safe to say it has higher contrast.

. In all likelhood, if the telescope with the "Best Contrast" (ie, blacker sky, which really doesn't have anything at all to do with contrast by the way) If you look though one and you see the sky background being brighter, this is more likely a function of the magnification giving a slighly larger exit pupil or better light transmission, and not any contrast improvement in the telescope. Assuming the exit pupil is IDENTICAL, the scope with the brighter sky background could actually have slightly better light transmission, or it could be that the eyepices you used. Maybe one was a very high light transmission eyepice, vs one with less light transmission.


Lets say you are observing a dark star field and you bring Sirius into the field of view. Remember that inferior optics scatter light all over the field of view and this can disrupt the striking dissimilarity.


See, dollar bills have EXTREMELY fine detail in them It is AMAZING how fine the detail can be! I put the telescopes the same distance from the dollar bill in a dark hallway at night.
My regards,
Ed


I learned this from Al Nagler many years ago and it's wonderful and it's a very wonderful way to test, I agree, but I enjoy viewing planets with the telescope since that is one of the things it was intended for to begin with. If I am unable to evaluate a telescope using stars, then I don't see the purpose of concerning myself over which telescope is better on planets. There are many reasons why the background could be brighter or darker in a telescope, but I have to be practical. Now I'm going to paste your post here once again and I have a little something here for you in the end to consider.

First, to include a 110mm telescope in a 4" refractor competition is not at all proper. There reason is that at the same magnifications, the 110mm scope is going to have a much much larger exit pupil.. I do the math on this all the time and you can too. Even small differences in magnification of two 102mm telescopes can greatly influence the area that the light pencil exiting the eyepiece influences the receptors on the retina. A difference for exampe of 15x in two 4" telescope is sufficient to completly destroy any direct comparisons.

The 110mm Telescope also 14.7 inch of light collection vs only 12.57 for the 4". This represents a 17% improvement in light gathering in the 110mm scope. This means that if you match the power with a 4" scope, the target is going to be 17% brighter in the 110mm scope. The 17% increase in BRIGHTNESS of the low contrast detail on planets is going to make a telescope even with less than perfect optics likely outperform the smaller telescope in both resolution AND low contrast detail detection. Brightness is actually a CRITICAL element for planetary observing.

Now the exit pupil issue applies even when apertures are identical. Here the need to match the magnificaiton is EXTREMELY important. In order to FAILRY test two telescopes side by side, the eyepieces have to provide almost the EXACT same exit pupil. To say that this telescope had "more contrast" because the sky looked blacker is HIGHLY subject to influence of the sizes of the exit pupil.. In all likelhood, if the telescope with the "Best Contrast" (ie, blacker sky, which really doesn't have anything at all to do with contrast by the way)is being used with an exit pupil even 10% in diameter smaller (.8mm vs. .72mm), the telescope with the larger exit pupil will show the sky to be brigher. In a 4" telescope, this is the difference between 157X and 171x). So, the magnifications have to be almost IDENTICAL to use sky brightness as a contrast comparison, which I don't think it really is...

Contrast is best measured using a test card. Judging contrast by sky brightness is not really a sound way to compare contrast. Lets say that you have two telescope with the same aperture and the same focal length. If you look though one and you see the sky background being brighter, this is more likely a function of the magnification giving a slighly larger exit pupil or better light transmission, and not any contrast improvement in the telescope. Assuming the exit pupil is IDENTICAL, the scope with the brighter sky background could actually have slightly better light transmission, or it could be that the eyepices you used. Maybe one was a very high light transmission eyepice, vs one with less light transmission.

Since you did not explicitly state that you made efforts to EXACTLY match the exit pupils of the 4" scopes, then I have to call into question the relevance of these different "Contrast" conclusions.

When I want to test contrast, what I use is a fresh dollar bill. If you have never tried this test, it can be VERY VERY informative.

See, dollar bills have EXTREMELY fine detail in them It is AMAZING how fine the detail can be! I put the telescopes the same distance from the dollar bill in a dark hallway at night. Because there are many differnt printed areas on the bill with different contrast elements, I find that I can EASLY see differences in sharpness and contrast.

I have compared many different telescopes using this method and I find it to be once of the most conclusive tests you can make.. Sky Brightness is to me quite meaningless. I owned an 80mm ED scope that using this test actually showed better contrast than a 120mm refractor. Faint, fine detial was simply more easily resolved in the much smaller (but CLEARLY higher quality) objective.

Next, while the test was supposed to include performance on "Clusters" to me, the most important attribute of how telescopes perfrom on clusters is OFF-AXIS performance. There was an almost total ommission on how these telescope performed off axis.. When you consider that Jupiter only occupies about 1/1000 of the low power view in a typical 4" refractor, this review literally ignored the other 99.9 percent of the field.

I DO however think that on-axis planetary performance is indeed an excellent way to compare two telescopes of the same aperture as long as the magnification is identical. Again, a difference of .07mm in the exit pupil though will skew the outcome, typically with the telescope enjoying the advantage of a bigger exit pupil doing better.

Sorry.. I don't mean to offend.. Only offering constructive critisim of your techniques.

I have no doubt that the Taks you tested came out on top.. Actually I think that Tak perhaps makes some of the finest optics on the planet. If they looked better on Jupiter or Saturn, I am not surprised.

I am just not sure if I agree with some of the other methods that were used to make the "Contrast" comparisons.

It is FAR FAR better to use test charts or something like a dollar bill in dark lighting to do contrast comparisons.

To be fair to you, I no longer read any of the American astronomy magazines because of their failure to adopt more advanced testing methods. Instead, I rely on work being done by amateur testers using optical benches..

If you looked a Mr. Rohrs test site, you would see that some of the WO telescopes did not fare well when compared to the Televue and Tak otpcis. Bench Testing that I have seen from Japan also showed the Tak and Televue scopes to be outstanding, along with Ziess and a few others.

Look at Photo Magazine tests too.. They use test charts to compare off-axis performance in Camera Lenses. They have been doing this for DECADES. Why don't amateurs do this when they do shootouts? The test charts don't lie. They are DESIGNED to show contrast and resolution differences. Nothing else works as well.

So, while I appreciate you and the groups extrordinary efforts, my own desire would be to see people start using less subjective testing methods and CAREFULLY controlling variable like exit pupil.

For any readers that haven't tried it, go point a couple of telescopes at a $5 Dollar Bill about 75 feet away. Making this comparison is easy and offers incredible insight into how telescopes compare. Pan around the bill.. Especially, the back of the bill.. Look at Mr. Lincoln. He offers one of the finest contrast targets imaginable.

I have used US Paper bills for years to compare optical performance and I find it FAR superrior to using the night sky. While it is STILL somewhat subjective, it is far easierl to judge performance this way than using just about anything else the ameture has (including the night sky). If you really want to see how "Sharp" and "Contrasty" two telescopes are, this is the way to go.

If you do the test during the day, slight variences in exit pupil are often eliminated because of the brightness being higher.


Better yet, a contrast/resolution test chart.


Try to think about all this while you're viewing a planet.
 

#350 Daniel Mounsey

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Posted 07 September 2008 - 10:43 PM

Question, Dan. The FSQs you tested, were they the older flourite models or the newer, shorter ED quads? I had one of the older ones and it was quite good visually, especially with the extender Q attached. I just got an ED version and the new extender ED from Art. Haven't had that rig out yet -- was planning on it but cloudy tonight here -- but maybe I missed it in your report but couldn't tell which version you used.

Any thought on the newer 106 vs the original? Have you tried the new one yet? Dave


No, they were the newer versions. I've tested both the older and newer versions but not side by side before, so that would be a difficult call to make. The new model is called the Q and there is now a BABY Q 85mm. Comes with a cigare and birth certificate.
 


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