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4" Apochromatic Hyper Shootout

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#301 Daniel Mounsey

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Posted 05 September 2008 - 04:19 PM

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:
 

#302 Daniel Mounsey

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Posted 05 September 2008 - 04:22 PM

Hi Charlie,

It would depend on the climate as you mentioned but it's very interesting to get your feedback. Thanks for sharing this. :)
 

#303 Chris Schroeder

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Posted 05 September 2008 - 04:24 PM

Thank you Daniel for the great review, I really enjoyed reading it.
 

#304 Jason B

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Posted 05 September 2008 - 08:09 PM

Daniel,
That was one great read. Thanks for sharing all your hard work!

Are your fingers/hand recovered from all that typing?
 

#305 spaceydee

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Posted 05 September 2008 - 08:38 PM

Well, I've decided not to trade up! :) Thanks for the review!
 

#306 Daniel Mounsey

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Posted 05 September 2008 - 09:17 PM

Daniel,
That was one great read. Thanks for sharing all your hard work!

Are your fingers/hand recovered from all that typing?




Jason,
:lol: No, my fingers are still tired. Judging by the way you look in that picture, you look a bit worked yourself :lol: Seriously though everyone, thank you so much for all the kind words. You have all been worth the work, seriously. :smirk:

Yes, the doublets are still keepers IMO. I will end up with an FC or FS again.
 

#307 Zhengyi

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Posted 05 September 2008 - 09:27 PM

Thanks for the review Daniel. Great work.
 

#308 Rusty

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Posted 05 September 2008 - 10:33 PM

Great job, Dr. D - making the comparo effort is especially appreciated! :waytogo:
 

#309 APM M.Ludes

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Posted 06 September 2008 - 04:30 AM

Daniel,

you getting my full applause here for your review.
I believe to you and your team that you did the best possible objective review you can with the given scopes.
I found from my self a very little disagreement in your test, espacialy regards the scope you got to me, but thats the only thing I would differ with your result.

You did a very fair and superlative job with your Team, congratulations from my side !!!!!!!!!!!

I like to say a word about the question regards contrast between FS and TSA, I know both modells very well, have tested many and sold many, I am always coming back to the FS 102 ( in case my own testing show on the specific sample it has best sphericlal correction and perfect centering)

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.

But our sky is not a optical bench .

The Triplet has another better contrast from the his better colorcorrection.

False color from chromatical aberration is a aberration and a aberration is a fault , a optical fault , and such optical fault degrease one of the many diffrent contrasted we dealing with .

The TSA does not have that level of fault on the chromatical aberration.

Therefore the FS 102 has the higher contrast due 2 perfect elements only with less scatter , and the TSA has the better contrast at the colorcorrection side >
final result : both meet each other in the center and show to your eye the same degree of contrast.

The FS loose a bit contrast due left chromatical aberration, the TSA due the use of a third element.

I self found if both are equal perfect , Jupiter want the TSA , because the better colorcorrection show you little hint of fine belt details better.
But Doublestars want the FS :-)

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

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

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 )
 

#310 Fomalhaut

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Posted 06 September 2008 - 05:03 AM

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
 

#311 islandsteve11

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Posted 06 September 2008 - 06:54 AM

Daniel

Thank you from the bottom of the little black lump of coal I've got for a heart. :rofl5:

Truly WELL DONE! :salute:
 

#312 ryderc1

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Posted 06 September 2008 - 07:39 AM

Hi Charlie,

It would depend on the climate as you mentioned but it's very interesting to get your feedback. Thanks for sharing this. :)


Hi Dan-

Needless to say, I was bummed out about the cold weather issues with the TMB CNC Classic tubes in my west of Boston location. I owned three different scopes before I figured out the cause for their suboptimal winter performance(two 100/800's and one 105/650). Too bad because the optics themselves were world class and in warmer weather were superb performers.

Someone else I know in NH had similar issues with a LOMO 80/600 triplet in a carbon fiber tube. On cold winter nights he had to remove the eyepiece and tilt the nose of the scope down and let the warmer internal air escape the tube to restore thermal equilibrium. He needed to do this for about 5 minutes every 30 minutes or so.

The critical factor was the amount and rate at which temperatures were falling; if too much too fast the scopes just couldn't keep up and views would suffer.

My experiences and his taught me to avoid non metal OTA's in my climate for winter viewing.

Charlie
 

#313 Dave Novoselsky

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Posted 06 September 2008 - 08:38 AM

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 famous 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


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
 

#314 Daniel Mounsey

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Posted 06 September 2008 - 09:27 AM

Hi Daniel, great shootout review!! Do you have any idea where in the list a TMB 105/650 (or SV/TMB 105/650) would fit? I have had the SV version for several years and am very impressed. Performance is better than the TV102 I also had.


Eddie,

As I mentioned, I would be happy to try an answer questions like this. Sorry I didn't answer this earlier. About three years ago, a friend of mine named Darren Thibodeau had three scopes, an FSQ106, FS102 and the 105 you just spoke of because a friend of his was considering selling it for something else, but had no idea as to how good it actually was. It amzes me what people stumble on without even realizing it, haha. I go through the trouble to find wonderful scopes and he just had no idea. That night, I only got a chance to use the 105. To this day, that apo remains vivid in my memory and I'll tell you why. I did not make it part of this review because I was unable to test it side by side with the others, but I spent a good amount of time viewing Jupiter with it and star testing it. Out of every apo I've star tested, the 105 was absolutely perfect and I mean perfect! No false color and both rings so identical, that it was literally impossible to tell the difference from inside or outside of focus. Seeing was great that night and Jupiter just snapped right in. When star tests in triplets are like this, they snap like crazy and that's the sign of a fantastic scope. I'm sure it would have been right up there with the best. Best star test I ever saw. :)
 

#315 Alan A.

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Posted 06 September 2008 - 10:33 AM

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
 

#316 MrGrytt

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Posted 06 September 2008 - 11:03 AM

Out of every apo I've star tested, the 105 was absolutely perfect and I mean perfect! No false color and both rings so identical, that it was literally impossible to tell the difference from inside or outside of focus. Seeing was great that night and Jupiter just snapped right in. When star tests in triplets are like this, they snap like crazy and that's the sign of a fantastic scope. I'm sure it would have been right up there with the best. Best star test I ever saw. :)


I had also thought the 105/650 was sadly missing from the shootout. The 100/800 is potentially even better and should surely be in the shootout if it was still available. Sadly it isn't, and the demand for great 4 inch optics is still there.

My sample of the 105/650 is excellent and gives similar star test results to those you describe. Definitely a keeper. The only times I've seen better star test results were when testing optics that were significantly slower.

Harvey
 

#317 Jared

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Posted 06 September 2008 - 11:59 AM

Thanks much for posting this, Daniel! I own a William Optics FLT-110-TEC that I knew was special from my first views through it. Nice to know it wasn't an aberration. It's the only scope I have ever owned that I never once thought of selling. Now I've just to to make sure I avoid looking through any Tak TSA's (for fear of creating scope envy). :)
 

#318 Denimsky

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Posted 06 September 2008 - 12:55 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?
 

#319 Eddgie

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Posted 06 September 2008 - 02:36 PM

Hello Daniel.

Doing reviews is a lot of work, yes? I am sure everyone here appreciates your efforts. I do, and I did enjoy reading the review.

No offense intended, but I was not all that taken with many aspects of the review though.

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.

Again.. I absolutely intend no offense. I consider these forums an open dialog and wanted to share my own thoughts on the matter.

And I DID enjoy the review, and I am NOT surprised that the TAKs finished on top and that the Televue's were close behind and that the 110mm scope did better than the Televues.

My regards,
Ed
 

#320 Starlighter

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Posted 06 September 2008 - 02:45 PM

With it constantly shrinking, I'd think using a dollar bill for testing purposes would have serious disadvantages.
 

#321 andydj5xp

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Posted 06 September 2008 - 03:24 PM

Eddgie: "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."


Ed,
you are the first person to recommend the very same thing I've done for some years now with great success. My test target is shown in the attached picture.

Andreas

Attached Thumbnails

  • 2627708-Testvorlage_1.jpg

 

#322 Eddgie

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Posted 06 September 2008 - 03:32 PM

LOL.. Yes, but that means that the details is getting even more challanging to see!
 

#323 nirvanix

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Posted 06 September 2008 - 03:43 PM

Thank you Daniel, what a wonderful review. You have a talent for writing. I felt that I was standing right along side you in that hyper shoot-out.

Please write more stuff soon!
 

#324 Pasquale

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Posted 06 September 2008 - 03:50 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 :waytogo:
 

#325 Starlighter

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Posted 06 September 2008 - 04:35 PM

I see you're not using the US dollar. Maybe your method is a good one after all. :lol:
 


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