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AP Mak 10" what the next best thing

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#1 HCR32

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Posted 10 July 2012 - 06:10 AM

Owning an AP Mak 10" is something special I dont own one and I know what it would be like. Anyway it would be probably more special then I can dream. Chance of getting one zero to none. So what the next best Mak that is available and can put up a fight??

#2 Cotts

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Posted 10 July 2012 - 07:12 AM

I think TEC made a large(10"?) Mak/cass but these are also rare instruments. You'll most likely be able to get a 10" or larger Mak/cass if you look into the APM/Matthias Wirth customized scopes with Russian Intes glass. They are the best quality scopes of this type that are actually available.

there is also the Mak/Newt configuration which Mr. Wirth also puts together. You can get a 10" of this type as well.

They can be seen at the APM website.

Dave

#3 jmiele

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Posted 10 July 2012 - 07:50 AM

I'm with Cotts on this. I have a TEC MC200/F15.5 and it's an awesome instrument. The 8" is also a rare bird..

Best, Joe

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#4 RAKing

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Posted 10 July 2012 - 07:55 AM

Intes-Micro will build a 10 inch Mak for you with deluxe optics. That is probably the best "that is available".

I have a little TEC 6 and they are very hard to find. Yuri only made 50 of these and mine isn't going anywhere soon. :) IIRC, he made small batches of the bigger sizes (8 and 10 inches), too. They offer stunning views and are also very expensive.

I also have an STF-Mirage Deluxe 8 inch, but I don't think they made anything bigger. It is another incredible scope - I think the Russians do very good optics.

Santel made a 9 inch, but I don't know how hard they are to find.

Hope this helps,

Ron

#5 Eddgie

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Posted 10 July 2012 - 08:16 AM

If you can't afford the AP, you may not be able to afford some of the other choices mentioned either.

Assuming budget is the issue, then probably the Intes Micro MK91 will be about the largest "affordable" MCT that can be somewhat easily found on the used market (I don't think they are made in serial production anymore). I have seen these sell from between $3500 and $4000 USD.

These have excellent optics.

APM lists Intes Micro - Alter M1015 for about $9200 Euros.

Not exactly sure what the appeal of this kind of scope would be. The size and weight make it almost an observatory type scope.

My guess is that the resason that these are so expensive is becuase the demand is so low that they are likely only made on demand.

And they are so highly specialized that most people would not want to spend that kind of money.

Especially when you can get a perfect 10" Newtonian for a fraction of the price that will do about as well on extended targets and offer a much wider true field.

But if it is a big MCT that you want, the MK 91 is about the most afforedable large aperture MCT that generally shows up on the used market at a "reasonable" price.

#6 brianb11213

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Posted 10 July 2012 - 08:22 AM

Cautionary tale: even small Maks cool slowly. Maks over 7 to 8" probably never will cool to ambient, without a considerable amount of assistance with active fans etc. It really doesn't matter how perfect the optics are, if the scope isn't cooled to ambient.

#7 elwaine

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Posted 10 July 2012 - 09:06 AM

My 8" Intes Alter m809 (formerly Cotts' m809) is no slacker when it comes to putting up great views. It weighs only 22 lbs and cools well with the fan assist. Because they are underrated, resale values are much lower than what they should be. I've been thinking of selling it but not sure I want to part with such a fine scope for 3Gs or so.

#8 Paul G

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Posted 10 July 2012 - 09:08 AM

Valery Deryuzhin of Aries Instrument Company has sold 10" Mak-Cass scopes with the same optical design as the AP (he designed the optics for the AP Mak) and similar cooling. In a post here on CN in 12/2008 he said he was selling his personal 10" Mak, and someone here on CN recently purchased one from Aries, he could give you the specifics. Maybe Valery can join this discussion with more up to date info.

#9 EddWen

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Posted 10 July 2012 - 11:14 AM

A Mak design will cool at the same rate as a SCT of similar size when exposed to the night sky. The meniscus of a Mak is thicker, but cools rapidly. The mirrors of either a Mak or SCT are similar in size and mass and cool at similar rates.

I frequently use my Questar and never seem to have an issue with cooling.

A-P 10" Maks cool without fans in ~15-20 minutes.

I have a big Mak with fans that cools within ~15-20 minutes.



Cautionary tale: even small Maks cool slowly. Maks over 7 to 8" probably never will cool to ambient, without a considerable amount of assistance with active fans etc. It really doesn't matter how perfect the optics are, if the scope isn't cooled to ambient.



#10 houser23

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Posted 10 July 2012 - 02:20 PM

Why would you be after a AP Mak when you own a perfectly good scope in the Mewlon 250? :scratchhead:

#11 Eddgie

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Posted 10 July 2012 - 02:55 PM

While the Mewlons seem to enjoy a high reputation, the ones that I have seen test reports on suggest that there are many Celestron SCTs out there with better optical quality.

Also, the total central obstruction of the Mewlon as compared to the 250mm f/15 MCTs is much larger. While the CO itself is often less than 30%, this design also has a spider vane which is equivilent to perhaps another 2% obstrution, bringing the system over 30%. The f/15 MCTs tend to have much smaller central obstructions and of course do not have any secondary spider.

In addition, based on these tests, the Mewlons seem to be in the "Very good" catagory, vs Intes Micro which tends to almost always be in the Excellent catagory.


Mewlon 210 with .894 Strehl after being repaird for astigmatism

Mewlon 210 with .925 Strehl (wich would have been much better if the astigmatism were removed)

Mewlon 210 with .94 strehl

Mewlon 210 with .042 Strhel

By comparison, here are a couple of Intes Micro scopes...

Alter 809 with .981 Strehl

Intes 703 with .98 Streah


But the price of the MCTs is simply so high that a premium mirror 10" Netwonian will match them for performnace and offer far wider fields of view, making these big MCTs seem to be a very poor value proposition.

And I have seen C11s that bench tested better than the 210 Mewlon, and with their slightly bigger aperture, I would expect them to perform at least similarly to the 250.

To be fair, I looked around to see if I could find any bench tests on the 250 and could not, but considering that none of these included is above .95, I don't know why anyone would expect the 250 to be better. But the fact is that I do not know this for sure. I can only go by the fact that no other Mewlons I have seen tested have been on par with the Intes Micro scopes.

And of course the AP would be close to perfection. Mr. Christen I don't think could sleep at night if it were not.

Again, I would question the wisdom of spending $9000 on a 10" MCT (if you could get one for this price) when you could duplicate the performance with a high quality 10" Newtonian if you didn't mind loosing some true field of view by going to a 20% diagonal. Who cares that this scope would have coma if you are only going to use if for the same narrow field viewing that an f/15 MCT could provide. And with a Paracorr, you could have wide fields as well.

I simply don't understand why someone would spend so much money on a 10" MCT when it is so easy to match their performance at a tiny fraction of the price.

#12 Erik Bakker

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Posted 10 July 2012 - 03:25 PM

Why would you be after a AP Mak when you own a perfectly good scope in the Mewlon 250? :scratchhead:


Jeff, you're the man :bow:

There is every reason to be a proud owner of the Mewlon 250 or the A-P 10" Mak. A-P makes great scopes for sure, I had an EDFS 130 for a decade. But so does Takahashi. If you have one of either, stop looking for the other. Start observing with what you have and keep doing that.

As for refractors, I prefer the Tak fluorites to the A-P triplets for visual use. When I bought my A-P in 1997, I had to wait for 3 months. Now the A-P refractors have wait-times in years, perhaps even decades for some scopes. They are good, but not THAT good. Honestly. Been there. For the money involved, get a (bigger) available scope from Tak, TEC, Zeiss or whatever other quality make you fancy. I have also seen some incredible Matthias Wirth scopes with Russian optics. Buy what is available and enjoy the universe with that. If you so desire, put your name on an A-P waiting list and see what happens. Or buy used. But be prepared that the quality is superb, but in many cases not superior to the other top makers.

That's just my experience. YMMV.

#13 Starhawk

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Posted 10 July 2012 - 03:30 PM

.042 Strehl Mewlon 210, Eddgie? I'll bet the owner thought about complaining on that one!

-Rich

#14 Paul G

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Posted 10 July 2012 - 06:09 PM

Again, I would question the wisdom of spending $9000 on a 10" MCT (if you could get one for this price) when you could duplicate the performance with a high quality 10" Newtonian if you didn't mind loosing some true field of view by going to a 20% diagonal. Who cares that this scope would have coma if you are only going to use if for the same narrow field viewing that an f/15 MCT could provide. And with a Paracorr, you could have wide fields as well.

I simply don't understand why someone would spend so much money on a 10" MCT when it is so easy to match their performance at a tiny fraction of the price.


I've used a 10" Newt optimized for planetary observing and it was a fine instrument. But my 10" Mak has better thermal characteristics, is coma free, is permanently collimated, and rides comfortably on a Mach1 mount. Every scope has its niche.

#15 JJK

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Posted 10 July 2012 - 08:56 PM

While the Mewlons seem to enjoy a high reputation, the ones that I have seen test reports on suggest that there are many Celestron SCTs out there with better optical quality.

SNIP

And I have seen C11s that bench tested better than the 210 Mewlon, and with their slightly bigger aperture, I would expect them to perform at least similarly to the 250.

SNIP

I simply don't understand why someone would spend so much money on a 10" MCT when it is so easy to match their performance at a tiny fraction of the price.


Eddgie, with all due respect, I have yet to see a C8 or C11 that outperforms either my AP 10" Mak-Cass or Tak Mewlon 300. They do not even come close in terms of planetary, Lunar, or DSO visual work. The AP & Tak seem to have smoother optics and can be pushed, with good effect, to greater magnification when needed.

That said, the AP Mak-Cass is too rare to lust after (unless one likes to be frustrated and/or depressed) and a Tak Mewlon 300 is considerably more expensive than a C-11 (though I've seen used Mewlon 250s for tempting prices). The Celestrons SCTs represent good value, and I can see them filling a niche in my arsenal someday, but they are generally not blessed with precision optics or mechanicals.

#16 jmiele

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Posted 10 July 2012 - 10:04 PM

I don't agree with using selected test results to base your case on. Eddgie tends to do that regularly. Individual test samples like thought found at Wolfgang's site are isolated. They may reflect accurate results for that sample but are NOT something to justify quality assurance by a maker. An 1/8th wave mirror by Celestron is bound to be produced every now and then just by accident given their volume. But if Eddgie wants to believe that an average C-8 or 11 is going to beat up an AP Mak or Tak Mewlon....fine. The problem is his posts mislead folks that are doing google searches or searching posts at CN. Eddgie, your Great Celestron mirror was as much a fluke as the bad Takahashi was and NOT something folks should be basing buying decisions on!


Joe

#17 Eddgie

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Posted 10 July 2012 - 10:58 PM

Nowhere did I say that a C8 or C11 was going to beat a 10" f/15MCT.

If you can find where I said that, then please point it out and I will apologize.

What I did say was that the quality of the Mewlons tested by Rohr did not show them to be at the same quality level of the Intes Micro scopes, and I provided links to tests that show this.

I also said that Rohr has several reports of Celstron SCTs that are made to the same quality as some of the Mewlons tested.

Nowhere did I say that a C8 would outperform any of these scopes.

The numbers speak for themselves. The Mewlons don't seem to have as consistently excellent quailty as the Intes Micros.

Please don't put words into my mouth.

I did say that you could match the performance of the AP 10" scope with a Newtonian built with the same small secondary mirror and premium optics.

It would be larger, but it would perform at well, but at a fraction of the price.

But nowhere did I say that this or that Celestron would outperform anything. I only said that Rorh has tested Celestrons with as good or better optical quality as the Mewlons in the links I provided.

Like this one:

C11 With .95 Strehl

Or this one:
C11 With .966 Strehl

Again, I am not saying that either of these would match the AP 10". The central obstruction is much to large.

I only said that I have seen Celestron scopes tested with higher quality than the Mewlons I referenced.

I know, the facts hurt sometimes, but these are just facts. I did not attempt to compare performance of Celestrons, only quality.

And these links pretty much bear out my messeage.

I said that the tests of the Mewlons I have seen have shown them to have optics that are no better than many Celestron SCTs, and I provided the data.

People may call me names if they choose, but unless they can produce something that discredits the facts I have provided, then a reasonable person I think would have to accept that Mewlons do not appear to be made to consistently near perfect levels of optical quality.

Neither are Celestrons.

Intes Micro Deluxe scopes though.. Now that is a different story.




#18 Erik Bakker

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Posted 11 July 2012 - 02:05 AM

Strehl can be an indication of the quality seen at the eyepiece, but not necessarily so. It is a measure of the large scale geometric surface. Carl Zambuto elaborates on that subject here. I too have seen Celestrons with quite high Strehls that certainly looked better than some other SCT's. But never were they anything like the stunning optics in my Questar 7, nowhere near. At the eyepiece this was easily seen, both on the bench with an artificial star and on the night sky. Nowadays, scopes with 0.95 Strehl are considered by some as on the verge of acceptable. Yet the many Zeiss APQ's I've seen came with interferometric test reports in the 0.95-0.97 area. But the results at the eyepiece in these APQ's were exceptional, especially in the APQ 100/1000. In APQ100's with comparable Strehls, I preferred the image in the 100/1000 over the 100/640.

Under the night sky, a scope will always reveal it's inner self. And so will the observer. If these two match at a given moment in time, we have a satisfied user of a certain scope. Sample-sample match we might call that.



#19 vahe

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Posted 11 July 2012 - 06:47 AM

Yet the many Zeiss APQ's I've seen came with interferometric test reports in the 0.95-0.97 area. But the results at the eyepiece in these APQ's were exceptional, especially in the APQ 100/1000. In APQ100's with comparable Strehls, I preferred the image in the 100/1000 over the 100/640.


Zeiss provided polychromatic Strehls for thei APQ’s, (Strehl based on three primary colors) as far as I know no other manufacturer offers polychromatic Strehls for their telescopes for the simple reason that when tested with monochromatic light the numbers will always be much higher.

For example TEC-140 has a Monochromatic Strehl of 0.99, the polychromatic Strehl for that same scope according to Yuri will be somewhere around 0.93, you can see why manufacturers prefer to give you the most meaningless number, it sells better.

As for the APQ 100/640 vs 100/1000, all else equal the long focus version will always produce superior image.

Vahe

#20 jmiele

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Posted 11 July 2012 - 06:54 AM

Eddgie, I not going to call you names, nor did I. I said you cannot use a couple of test reports to credit or discredit a manufactures work. All these test show are "what" is "possible". Not what the standard output of the maker is. When you start making claims and posting "the same BTW" charts over and over, you are giving folks a false sense of things.

It'll tell you what. You want a new C14 Edge? Let's call a dealer and split one. We can have them ship it to Wolfgang for testing. If it comes back with a 93 Strehl you keep it. Anything below that, I keep it. I will donate it to the local school in your name. The kids will just have to early that diffraction limited isn't always based on seeing. :)

The bottom line is random samples from ANY maker don't mean a hill of beans. If fact, they mean less as they are normally being tested for a reason. Someone believes they have a problem, or a superb optic. The numbers you quote mean so little top makers like Carl Zambuto, don't even supply testing data any longer. They believe the eye should decide. Buy a new Zambuto equipped Starmaster and you're not getting the data sheet from Carl any more.

You're a smart guy and I respect much of what you post. It's a puzzle to me why you would insist "the data speaks for itself" (you did say that, correct?) to proclaim that Takahashi is an inferior maker and Celestron is better, simply based on several random samples.

You go on making your strong opinions known, I'll do the same. Do try to keep the emotion out of it though. It's unbecoming. :) Oh, and my offer stands for the C14.

Joe

#21 jmiele

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Posted 11 July 2012 - 06:58 AM

BTW Eddgie I edited my post to lower the Strehl from 95 (my original post) to a 93. To make things more appetizing. :)

Joe

#22 JJK

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Posted 11 July 2012 - 07:21 AM

Nowhere did I say that a C8 or C11 was going to beat a 10" f/15MCT.

If you can find where I said that, then please point it out and I will apologize.

What I did say was that the quality of the Mewlons tested by Rohr did not show them to be at the same quality level of the Intes Micro scopes, and I provided links to tests that show this.

I also said that Rohr has several reports of Celstron SCTs that are made to the same quality as some of the Mewlons tested.

Nowhere did I say that a C8 would outperform any of these scopes.

The numbers speak for themselves. The Mewlons don't seem to have as consistently excellent quailty as the Intes Micros.

Please don't put words into my mouth.

I did say that you could match the performance of the AP 10" scope with a Newtonian built with the same small secondary mirror and premium optics.

It would be larger, but it would perform at well, but at a fraction of the price.

But nowhere did I say that this or that Celestron would outperform anything. I only said that Rorh has tested Celestrons with as good or better optical quality as the Mewlons in the links I provided.

Like this one:

C11 With .95 Strehl

Or this one:
C11 With .966 Strehl

Again, I am not saying that either of these would match the AP 10". The central obstruction is much to large.

I only said that I have seen Celestron scopes tested with higher quality than the Mewlons I referenced.

I know, the facts hurt sometimes, but these are just facts. I did not attempt to compare performance of Celestrons, only quality.

And these links pretty much bear out my messeage.

I said that the tests of the Mewlons I have seen have shown them to have optics that are no better than many Celestron SCTs, and I provided the data.

People may call me names if they choose, but unless they can produce something that discredits the facts I have provided, then a reasonable person I think would have to accept that Mewlons do not appear to be made to consistently near perfect levels of optical quality.

Neither are Celestrons.

Intes Micro Deluxe scopes though.. Now that is a different story.



This is what you said.

"While the Mewlons seem to enjoy a high reputation, the ones that I have seen test reports on suggest that there are many Celestron SCTs out there with better optical quality."

What do you mean by "many"? Did you mean to suggest that the optics in Celestron OTAs on average is better than that of Tak Mewlons on average? While my observation sample set is not large (15 Taks, dozens of Celestrons), I have not yet seen a comparable size Celeston outperform a Tak (and of course not outperform an AP Mak-Cass).

In my experience, I have yet to see a Tak scope of any kind perform poorly (that doesn't mean they are all up to spec). I have yet to look through a C8 or C11 that would outperform even an AP155 f/7 (that doesn't mean there aren't exceptions).

The central obstruction difference of the AP Mak-Cass and Celestrons is not the only thing that separates the two different designs. The thermal characteristics of the AP are better, and the quality of AP's scopes optics, including that in the Mak-Cass, is much more consistent and of higher grade (figure and smoothness, as judged by the telescope's performance) than those made by Celestron. That doesn't mean to me that Celestron OTAs aren't worthy of consideration. Frankly, I can see getting a C14 someday.

#23 Eddgie

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Posted 11 July 2012 - 07:57 AM

"While the Mewlons seem to enjoy a high reputation, the ones that I have seen test reports on suggest that there are many Celestron SCTs out there with better optical quality."

This statement does not equal "A C8 or a C11 will perform better than an MCT or Mewlon". Nowhere did I say that the OP should buy a Celestron 8" or 11" SCT. My own recommendation was an Intes Micro 9", or a high quality 10" Newtonian with optimized secondary mirror size.

My post simply states that from a quality perspective, the Mewlons that have published tests on the internet don't seem to have quality that is serially in the excellent catagory, and that there are many Celestron telesopes that have been tested that have been shown to have better optical quality.

You inferred something that I in NO way said, that the performance of these scopes would be better than others.

Telescope performance is a combinatino of quaility and design. The design of an MCT with a very small secondary obstruction makes it very difficult for an SCT with a larger central obstruction to perform as well unless it is a bit larger.

And I published two links to Celestron telescopes that bench tested with better Strehl than the 5 Mewlon tests I posted. Rohr has tested many Celestron SCTs with Strehl above .95.

Not all Celestron scopes I have seen bench tested had better quality than Mewlons he tested, but many did.

You can go to Rohrs site to see tests on numerous telescopes.

Also, I have seen Celestron telescope tests on many other sites, including Yahoo Groups where several amateurs have done Roddier testing, and on Abberatoor, and on a Japanese fan site (hard to find because it is not in English).

This was my message and only this. The Mewlon does not appear to have the serial production quality that Intes Micro, TEC, or AP has in their MCTs. It also has a much larger obstruction than most of these other scopes.

Someone looking for a 10" MCT is likely looking for a high contrast planetary scope, and the Mewlons, based on the quality and the central obstruction is not going to be in the same class as these other scopes.

And I pointed out that many Celestron scopes that have been tested have shown quality that was better than the Mewlon scopes that I have seen tests for.

So, you think I said something that I did not say. Above is what I said, and if read it and don't attempt to read anything into it, you will see that it is all I said.

#24 jmiele

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Posted 11 July 2012 - 08:08 AM

Eddgie, I think amateur/hobbyist testing on Yahoo is not a place to look for consistent test data. I think will can all agree such inconsistent testing my multiple testers is antidotal at best. Perhaps I read more into your statements than I should have. I'll also admit that over time I've learned more about proper cooling of mirrored instruments. During my early experience with mass produced optics (many years ago) I may not have always consider cooling as much as I should have.

As I said Eddgie, you're a smart guy. Your contributions at CN have been many. I guess we go at it a bit as we both are strongly opinionated. :) All in good fun though..

Joe

#25 Eddgie

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Posted 11 July 2012 - 08:18 AM

And this...

In my experience, I have yet to see a Tak scope of any kind perform poorly (that doesn't mean they are all up to spec). I have yet to look through a C8 or C11 that would outperform even an AP155 f/7 (that doesn't mean there aren't exceptions).


About 3 years ago, a forum member that knew that I was into star testing contacted me. He had upgraded from a 4" Tak refractor to a 5" Tak refractor, but was concerned that the image in the new scope was no better than the image in the 4".

I was sketptical that he was star testing properly, so I worked with him in setting up the test properly.

He sent me images of the testing, and based on that, I suggested that the scope appeared to have more than a little spherical abberation. I suggested that he return the scope and request a new one.

Unknown to me, he was also in contact with Roland Christen, and was also sharing the test data with him. Mr. Christen did not offer to attempt to quantify the error (I did), but also agreed that the scope had some problem that was of sufficent magnitude that the owner had reason to be concerned, considering that it was a premium quality instrument.

The owner contacted the importer who did not want to replace the scope initially, but with evidence in hand, and two independent evalutions along with the star test data finally exchanged the telescope.

And the owner reported that the replacement performed to his expectations. The replacement also star tested much better than the original sample.

What this told me is that even Tak can sometimes ship a lemon. It is possible that the scope became damaged in shipment, but the error was not a centering or collimtion error. It was some kind of spherical abberation, plain and simple. With a 30% obstruction, the imbalance in the shadow breakout was pretty extreme. This size central obstruction is large enough that it will miminize any higher order sperical abberation, and this is what the scope was showing... Far more spherical abberation than should have been present in a premium telescope.

And of course if you looked at Rohr's page, you would see where Rohr had to correct a defect in a Mewlon that was shipped with a somewhat high level of astigmatism due to a poor method of attaching the secondary mirror to the carrier.

Rohr was able to correct the defect in his lab. Correcting the astigmatism raised the Strehl on that sample by about .05

My advice to you would be to spend as much time as I do looking around the web for bench tests on different telescopes. Soon you will get a feel for who really makes the highest quality telescopes on the market. Tak may make near perfect refractors, but clearly the Mewlons are not made to quite the same quality levels.

And just because a refractor says Takahashi on the side doesn't mean that it will always be without optical problems. This is why I am such a vocal proponent of learning the proper methods for star testing. In the case above, the owner was able to use the star test to determing that there was an optical issue with his Tak that was rather large for a premium instrument.


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