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Have you ever heard of the Schupman telescope?

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#26 kfrederick

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Posted 27 November 2013 - 07:24 AM

Be nice to have a talk on some new designs as we have Ed Jones developer of the off axis CHief design And John Wall developer of the Hipo And Peter Wise developer of the wise newt and Zerocromat and Mike Jones who devoloped the wide band Chief . I have one of Ed s Chiefs a 20 f8 /and a 17 wideband chief made with Mike . Here these guys are the invent guys !!show them respect and learn . There are many designs ATM should be all over .

#27 kfrederick

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Posted 27 November 2013 - 07:41 AM

I will start with my 20 inch f8 Chief It uses a regular newt primary and a 6 inch flat to fold it the primary is tilted so it is unobstructed and the images is corrected by two 4 inch lens that Ed Jones came up with second time out I used a 4.8 nangler with it . The wide band Chief was Mikes work on this design to make a better CHief it has a Hyperbolic primary and spherical secondary optics the image is corrected with two 4 inch lens . I think the 17 has the smallest spot plots than any telescope APO 17 .. On the 17 with the help of Dave O We made a better way of holding the top optics IMO Here is the only pic I have with ED and the 20 unobstructed

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#28 Crayfordjon

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Posted 27 November 2013 - 10:40 AM

Ed's design is certainly good, there you see, there are some of you ATM'ers who are interested in innovation and new ideas, I researched dialytes for many years before I hit gold with the retro focal dialyte, it has been developed by others who have certainly improved on the initial concept. :cool: :cool:

#29 Ed Jones

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Posted 27 November 2013 - 11:06 AM

I think the Schupmann is more limited by astigmatism than color in the field but you're right it does have a small field of view. I think you are referring to this Zerochromat design. It's an interesting design but doesn't cover the full visible range 400 to 750 nm. Compare it to this 7 inch F/10 Jones-Medial.

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#30 DAVIDG

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Posted 27 November 2013 - 12:33 PM

Schupmanns are design to be long focus instrumentts for doing high resolution planetary, double star and lunar work.
For an ATM one has to consider how difficult the design is make vs the cost and performance. The fact that multiple examples of Schupmanns have been made by amateurs is a big plus for the design along with the fact that a book has written on how to make them. It is has 5 surfaces and depending on the design either all 5 are spherical or 4 out of 5 are. It is made from two pieces of cheapest optical glass you can buy that is BK-7 and the tolerance are much looser then a typical achromat let alone some more exotic design that don't perform as well and have more elements.
I made three optical set on my kitchen table. As for testing it was done using a typical knife edge test and Ronchi screen. The only device I had that the average ATM doesn't is an optical flat to do double pass autocollimation but if your going to do lens work an flat is piece of equipment you need. Flats show up on places like Ebay and for not much money.
Here is a picture of 4" f/12 I made. The cost of the optics and OTA was under $100. What 4" APO can you buy for under $100 ?

- Dave

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#31 Crayfordjon

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Posted 27 November 2013 - 02:00 PM

Nobody has bothered to shew the originator of this thread the difference between a classical dialyte as concieved in the 18th century, the Schupmann, and the RFD.

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#32 Chuck Hards

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Posted 27 November 2013 - 02:05 PM

I'm having a hard time correlating figure 2 with the photo of Dave's 4". Looks like a different optical layout.

#33 DAVIDG

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Posted 27 November 2013 - 02:38 PM

Chuck,
Here is the optical layout and spot diagram for my 4" f/12. It is the typical optical layout made by Atm's. The small field lens in the above drawing has been replaced by a small spherical field mirror. It is easy to make and reduces the size of the OTA by folding the light path back on itself. What is not shown is a built in star diagonal to place the focuser on top of the OTA as you see in pictures I've posted of the Schupmanns I've made.
You can also see from the spot diagram that the in focus row of spots which is the middle row show all the wavelengths well within the Airy disk. Hence zero false color.

- Dave

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#34 Chuck Hards

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Posted 27 November 2013 - 02:43 PM

Ok Dave, I see it now. Thanks!

#35 DAVIDG

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Posted 27 November 2013 - 02:51 PM

I have a book case full of books on optical designs and many of them show wonderful performance on paper but to get that performance the system needs to be able to be built to tolerances needed.
That is one of great features of a modern Schupmann. The average guy can build them. Here is a picture from Stellafane a few years ago were 5 of them showed up. They range in diameter from 4" to 7".

- Dave

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#36 Chuck Hards

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Posted 27 November 2013 - 09:08 PM

^ Isn't that the only strip of level ground on the entire mountain?

#37 Crayfordjon

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Posted 28 November 2013 - 03:11 AM

Chuck the second figure diagramatic only, it does correlate with the layout of the Schupmann system. Actually the Retro is not too difficult to make, but it involves more work making the small lenses. I am of course addressing the optical engineer element on the ATM forum who would find making an RFD an interesting project.

#38 wiseone

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Posted 30 November 2013 - 06:22 AM

Very interesting spots - very good over a wide range of colours. The retrofocal dialyte design can be made to be good over a reasonable range of colours, certainly for the visual range (490nm to 620nm). The most interesting thing about the attached spot diagram is the relative insensitivity to focus. The Schupmann spots show a very much greater tightness on focus position - about 50 times that of a dialyte, which is possibly why the Schupmann has a reputation for being rather 'tweaky'.
You can't have everything in a design - all is a compromise.

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#39 Crayfordjon

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Posted 30 November 2013 - 08:14 AM

The Retro has a greater range of design capabilities than a Schup, which is limited by the design of the corrector system, and is a Schup truly APO? a retro definately is. :cool:

#40 DAVIDG

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Posted 30 November 2013 - 01:07 PM

When it comes to a Schupmann being "tweaky", these statements are coming from people that have never built one. There have been a number of Schupmanns built over the years. The largest being the 1 meter Swedish solar telescope that holds the record for the highest resolution ground based solar images. http://www.solarphys...rmer03meter.pdf When the "Pro's" picked this design they understood the optical excellent of it and robustance of the design. A Schupmann has much wider tolerances then a typical achromat, yet has much better color correction and better then any typical APO. It is also easier to test the optics.
Here is a picture of another homemade Schupmann by Gerry Logan from 2012. It is a 7" f/10 in which Gerry added an optical flat to fold the light path so the OTA is only about 3 feet in length.

- Dave

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#41 Crayfordjon

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Posted 01 December 2013 - 02:00 AM

Yes we have heard of the metre swedish scope usual, but what we are trying to do is introduce new ideas into ATM, and our experience is that new ideas are rejected on a knee jerk regularity, Why?, I find this fascinating this resistance to change.

#42 Schubert

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Posted 01 December 2013 - 02:39 AM

A schuppman is tweaky yes, but so is a newt.
If you ever collimated a newt and found it hairy, donĀ“t bother with a Schuppman. It has 1 extra set of alignmentscrews at the relay-mirror.
Those are the screws you use to tune out atmospheric dispersion as well.
It just plain works if you make a good solid tail-piece assembly which holds the focuser, diagonal and the relay-mirror and allows you to tweak them all.

Furthermore a Schuppman is relatively light.
A 30cm schuppmann has about the same mount-requirements as a 7 inch Apo.

#43 wiseone

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Posted 01 December 2013 - 05:47 AM

As the Schupmann design is so good, it seems odd that it has never been commercialised. In a similar vein, the Schiefspeigler design has also not been commercialised - I made a 4 1/4 inch Schief back in 1976, and made much use of it, showing dozens of schoolchildren at my son's school the wonders of the night sky. Even a party of nuns! It was 'tea and stars' and was a resounding success - and provided free. All under the wonderful South African skies.

The dialyte refractor that I designed from John Wall's 30 inch dialyte worked very well indeed, but was far too expensive to make, and I had trouble with the triplet lens in the corrector chain of lenses. Not commercially feasible.

The latest configuration makes use of an absolute minimum of corrector lenses (one singlet and two identical doublets), and even has half the lateral colour of the original design, with identical performance on-axis. It has the bonus of not being 'tweaky' at all.

#44 kfrederick

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Posted 01 December 2013 - 08:59 AM

Yes we have heard of the metre swedish scope usual, but what we are trying to do is introduce new ideas into ATM, and our experience is that new ideas are rejected on a knee jerk regularity, Why?, I find this fascinating this resistance to change.

John I know what you are saying Same thing with the Chief It is better and could be even better!! But even the people who know will say not say . The big boys have no intrest in a better telescope and the ATMs just wont to by a cheep mirror and put it in a tube and call them ATM / Nothing wrong with a Schup why none out there except for ATM ? The pros do not seem interested in a better telescope design .Taking a chance . I respect the work you and Peter have done . And excited to see what you come up with next .

#45 DAVIDG

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Posted 01 December 2013 - 11:36 AM

The "acid test" for a new design is that the average amateur has to be able to make it and it needs to perform to an acceptable level once it is built. The Schupmann design has proven this time after times. I've built three set of optics on my kitchen table. The OTA required only simple tools and the total cost was less then $100 for each telescope. So until these other design show multiple examples of functional telescopes made by different people over a period of few years, they will never become popular. If the average guy tries to make one of these new designs and finds it too difficult, then the design will be forgotten. When some looks thru the eyepiece they better be able to see the difference in the image quality or they will quickly come to the conclusion that building a simple newtonian is a better use of time and money.

I keep seeing talk about some of these new design but I have yet to see a step by step plan on how to build one. For other designs there are books, articles and website that provide the EXACT details on how it is done. This is true of the Schupmann and why it has been built. Showing a one or two examples doesn't cut it. Show the world EXACTLY how to build one, the cost involved, were to get the materials, how to make and test the optics, what the tolerance are and then maybe you'll get a following.

- Dave

#46 DAVIDG

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Posted 01 December 2013 - 05:19 PM

. In a similar vein, the Schiefspeigler design has also not been commercialised - I made a 4 1/4 inch Schief back in 1976, and made much use of it, showing dozens of schoolchildren at my son's school the wonders of the night sky. Even a party of nuns! It was 'tea and stars' and was a resounding success - and provided free. All under the wonderful South African skies.


The Kutter Schief has been commericalized by a couple of companies over the years. It is still being sold by AOK Swiss in both a 4" and 6" aperture. http://www.aokswiss.ch/index_tel.html It is also still popular with ATM's and we have an active site on Yahoo Groups "Schiefbuilders". From the information on this site a number of Schiefs have been built over the years. Again the secret is to provide people with exact plans and information on how it is done and examples of scopes that have been built so they can see it is a doable project. Also when people do look thru the eyepiece they do show great images and show it is worth the effort to make one. Here is a picture of one made by my good friend Gary Fuchs.

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#47 Gary Fuchs

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Posted 01 December 2013 - 11:11 PM

Thanks Dave!

Schiefs and Schupmanns are great scopes.

When I made my Schief an otherwise knowledgeable friend commented that they're hard to collimate. In fact, they're quite easy to collimate--provided you set up the adjustments the way Knab shows. I think it's considerably easier than a Newt. And they seem to hold it quite well too, even through fairly rough handling.

Dave recommended that I follow Knab's method--and I did. Like Dave said, that was well documented and even without a technical/scientific background I was able to understand and implement it. If I can do it...

As for why these scopes aren't more accepted commercially and known, I think it's partly because of the sort of mistaken preconceptions like those I encountered from my friend and others subsequently.

The information and guidance is easily available for either scope. Likewise the materials and tools needed--nothing fancy.

To me it's like choosing a car. Which one is best; which of course depends...a minivan isn't better than a sedan and that's not better than a roadster. Apples and oranges.

Gary

#48 Crayfordjon

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Posted 02 December 2013 - 01:57 AM

David is right of course, the retro is a scope for those who like forbidden fruit,it is a challenge to build by the amateur, perhaps his scope should be aired on a different forum. The Idea of these postings is to introduce a new and exciting system.

#49 Dave O

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Posted 02 December 2013 - 03:06 AM

I've often wondered if 'patents' and 'royalties' (and lawyers) get in the way of commercial production of some of these more modern designs?

#50 Crayfordjon

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Posted 02 December 2013 - 03:26 AM

Probably that too, but there is a reluctance to launch a new concept on the market in case it does not sell in the Telescope market, there is also an inate conservatism too that prevents the sale of something new, and therefore fishy.
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