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Old 17-05-2019, 04:19 PM
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Paul Haese
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AG12 correction resolved

It has taken nearly 12 months to go through every conceivable permutation of what could be causing the poor star shapes on the frames of the AG12.

First I obsessed about the collimation for months, many hours of checking and rechecking. Ensuring I was improving my accuracy all the time.

Then I went over all the adapters on the scope. I checked the ones that OOUK had made and the ones I had made by Precise Parts. A friend made an adapter and adjusted the OOUK ones to ensure everything was 100% square. The OOUK ones were not square and threads were running out by several thousandth of an inch.

Then I went over the installation and gluing of the mirrors in their respective cells. Making sure nothing was pinching or causing astigmatism. I found some astigmatism in the secondary but fixing that did not fix the problem.

Then I checked over the position of the focuser and the centre of secondary. That checked out fine.

In the end I took the advice of a friend who suggested that it was the corrector. I ran a laser through the corrector on a flat mirror and it was a little out. However when I ran the laser through the corrector and the scope at the same time it was significantly out. Even though the scope showed perfect collimation each time. So I ran another experiment which demonstrated that the threads on the Wynne corrector were too loose and not square to the line. I got a different result each time rotating the corrector around and using the tightening ring. After that I decided to use another corrector. I had to wait for some parts from TS in Germany which took some time but it confirmed what I was thinking. The OOUK Corrector is faulty.

The attached image confirms that theory. Taken with a TS GPU corrector. To boot it is sharper than the AG12 corrector. This image shows the corners and the centre. All looking good.

Now to get the corrector replaced or refunded for the cost of it.
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Click for full-size image (Test image GPU to AG12.jpg)
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  #2  
Old 17-05-2019, 05:32 PM
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Rigel003 (Graeme)
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Good news after an amazing saga. Most wouldn't have the patience to follow this through to a solution. Let's hope you get some financial satisfaction from the company.
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  #3  
Old 17-05-2019, 05:33 PM
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Slawomir (Suavi)
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Fantastic news Paul.

It was a long and not easy journey for sure, but now you have a beautiful perfectly collimated instrument and you must have learnt a lot about telescopes
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  #4  
Old 17-05-2019, 05:38 PM
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I wish you luck with OOUK....but at least, to coin a timely phrase, you are now "moving forward".
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  #5  
Old 17-05-2019, 06:44 PM
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That's awesome Paul, glad you finally figured it out. I'm still struggling with mine (ONTC newt), but I think I'm one step closer after some more experiments tonight.
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Old 17-05-2019, 06:59 PM
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Quote:
Originally Posted by Paul Haese View Post
It has taken nearly 12 months to go through every conceivable permutation of what could be causing the poor star shapes on the frames of the AG12.

First I obsessed about the collimation for months, many hours of checking and rechecking. Ensuring I was improving my accuracy all the time.

Then I went over all the adapters on the scope. I checked the ones that OOUK had made and the ones I had made by Precise Parts. A friend made an adapter and adjusted the OOUK ones to ensure everything was 100% square. The OOUK ones were not square and threads were running out by several thousandth of an inch.

Then I went over the installation and gluing of the mirrors in their respective cells. Making sure nothing was pinching or causing astigmatism. I found some astigmatism in the secondary but fixing that did not fix the problem.

Then I checked over the position of the focuser and the centre of secondary. That checked out fine.

In the end I took the advice of a friend who suggested that it was the corrector. I ran a laser through the corrector on a flat mirror and it was a little out. However when I ran the laser through the corrector and the scope at the same time it was significantly out. Even though the scope showed perfect collimation each time. So I ran another experiment which demonstrated that the threads on the Wynne corrector were too loose and not square to the line. I got a different result each time rotating the corrector around and using the tightening ring. After that I decided to use another corrector. I had to wait for some parts from TS in Germany which took some time but it confirmed what I was thinking. The OOUK Corrector is faulty.

The attached image confirms that theory. Taken with a TS GPU corrector. To boot it is sharper than the AG12 corrector. This image shows the corners and the centre. All looking good.

Now to get the corrector replaced or refunded for the cost of it.
Gee Paul - sounds like climbing an Everest!

You are really good at this stuff - you should honestly consider starting a telescope tuning/repair business!

Look forward to the images.

John K.
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  #7  
Old 18-05-2019, 08:30 AM
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Nice to see you have it sorted, Paul.

Its always good to solve one of those pesky issues!
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  #8  
Old 18-05-2019, 09:52 AM
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Paul,
I could have warned you if I new that you were using an OOUK corrector.
When I was salvaging one of their "Hyper-Super" 10" ODK disasters, I turned up a jig on the lathe and screwed in the corrector so that the lens housing was spinning true. Well, one of the three lenses was running out so badly that I had to reduce its diameter by 3mm in order to bring its optical centre to the optical axis. With a meniscus lens even a small wedge error will displace the optical centre a lot more than one would expect. The OOUK people don't seem to worry about such things.
… and the spacers and the mounting of the lenses...
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Old 20-05-2019, 01:29 PM
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Well, that's good and bad news I guess?...mostly good, as at least you know now that you can have a working telescope, just need to get a new corrector. Perhaps go with a non OOUK one .....

Mike
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Old 20-05-2019, 01:54 PM
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Good God I admire your dedication Paul. By now I would have had Mike caber-toss it into the Molonglo.

A lot of money, frustration and grey matter finally giving results it should have out of the box.
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Old 20-05-2019, 02:21 PM
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Originally Posted by LewisM View Post
Good God I admire your dedication Paul. By now I would have had Mike caber-toss it into the Molonglo.

A lot of money, frustration and grey matter finally giving results it should have out of the box.
How to handle a defunct OOUK Wynn Corrector
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  #12  
Old 20-05-2019, 03:52 PM
LewisM
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How to handle a defunct OOUK Wynn Corrector
So, we can officially call you a tosser and be completely correct. Nice
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  #13  
Old 20-05-2019, 05:52 PM
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Thanks guys for the all the responses. It has been a tough time, but I had lots of good advice and ideas from quite a few people. I found that persistence pays off ultimately and yes it should have worked out of the box.

Quote:
Originally Posted by codemonkey View Post
That's awesome Paul, glad you finally figured it out. I'm still struggling with mine (ONTC newt), but I think I'm one step closer after some more experiments tonight.
Lee I feel your pain. I made a map of the possible causes of the problem and then systematically tried every conceivable solution to the problem. Finally once all possible causes were eliminated it became obvious that is was the corrector.

Quote:
Originally Posted by John K View Post
Gee Paul - sounds like climbing an Everest!

You are really good at this stuff - you should honestly consider starting a telescope tuning/repair business!

Look forward to the images.

John K.
Hmm not like climbing Everest John; and since you are the only person I personally know who has made the summit of Everest I am going to assume it was quite a lot tougher this this little mole hill.

I am not sure I would like to offer such a service. I can think of a few others who are infinitely better at this than me. Though never say never.

Quote:
Originally Posted by Stefan Buda View Post
Paul,
I could have warned you if I new that you were using an OOUK corrector.
When I was salvaging one of their "Hyper-Super" 10" ODK disasters, I turned up a jig on the lathe and screwed in the corrector so that the lens housing was spinning true. Well, one of the three lenses was running out so badly that I had to reduce its diameter by 3mm in order to bring its optical centre to the optical axis. With a meniscus lens even a small wedge error will displace the optical centre a lot more than one would expect. The OOUK people don't seem to worry about such things.
… and the spacers and the mounting of the lenses...
These are also my suspicions Stefan, that not only are the threads at fault but the lenses are causing problems too. I would be highly interested if you wanted to take a look at this for me though. Happy to pay for a fix too.

Quote:
Originally Posted by strongmanmike View Post
Well, that's good and bad news I guess?...mostly good, as at least you know now that you can have a working telescope, just need to get a new corrector. Perhaps go with a non OOUK one .....

Mike
Yes those are my thoughts too Mike. At least I know I can use the scope and the optics do appear to be quite sharp. That is quite a relief . If the corrector I have got cannot be fixed by someone here then I will be looking at something like a Paracor or maybe an ASA corrector which I believe are quite good. I don't think I will try to get OOUK to "fix" it, as that appears to be not possible.

Quote:
Originally Posted by LewisM View Post
Good God I admire your dedication Paul. By now I would have had Mike caber-toss it into the Molonglo.

A lot of money, frustration and grey matter finally giving results it should have out of the box.
Don't worry Lewis, there were several times I nearly did exactly that. I guess the important thing to remember is that I wanted good optics, a carbon tube, a sturdy primary assembly, a very stable focuser area and stable secondary. I got that but did not get the 50mm corrected field that the Wynne was supposed to provide.
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Old 21-05-2019, 06:33 AM
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Quote:
Originally Posted by Paul Haese View Post


These are also my suspicions Stefan, that not only are the threads at fault but the lenses are causing problems too. I would be highly interested if you wanted to take a look at this for me though. Happy to pay for a fix too.

I wouldn't mind having a go at it. If the lenses don't have too much wedge errors, I can rework the housing and make spacers that will hold the lenses in good alignment.
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Old 21-05-2019, 07:58 AM
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strongmanmike (Michael)
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Quote:
Originally Posted by Paul Haese View Post

Yes those are my thoughts too Mike. At least I know I can use the scope and the optics do appear to be quite sharp. That is quite a relief . If the corrector I have got cannot be fixed by someone here then I will be looking at something like a Paracor or maybe an ASA corrector which I believe are quite good. I don't think I will try to get OOUK to "fix" it, as that appears to be not possible.
What has been OOUK's suggested approach on the matter?

Mike
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Old 21-05-2019, 08:18 AM
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Originally Posted by Stefan Buda View Post
I wouldn't mind having a go at it. If the lenses don't have too much wedge errors, I can rework the housing and make spacers that will hold the lenses in good alignment.
Ok, can you PM me with your mailing address and I will send it ASAP. Thanks for doing that.


Quote:
Originally Posted by strongmanmike View Post
What has been OOUK's suggested approach on the matter?

Mike
Mike, it's not so much any suggestion which, but their idea is that it must be operator error and I have not set it up properly. Based on what I have seen; the threads on the adapters they made from camera to the corrector, machining of the tube rings, anodizing, general attention to detail and stories I have heard would suggest that they will just simply send it back and say there is nothing wrong with it, when I know this is not the case. They don't want to acknowledge that their production is the cause. I had to provide photos of the tube rings to get two of them replaced. They knew there were 4 rings damaged but they only replaced two. When I told them about that they said I did not tell them there were 4 when in fact I said all of the rings were damaged, they sold me the scope and did not know how many rings were sent . It's just more behavior the like that Steve witnessed. It just becomes frustrating and annoying. So it is better to see if it can be fixed here (once again thanks Stefan) or if it can't move on and buy a large corrector which will work. I think you might have got the last of the good correctors.
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Old 21-05-2019, 04:43 PM
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Well done Paul, your perseverance is a credit to your patience and drive!
What a p/r disaster that company is Australia though- gee I wouldn’t touch them with Mikes’ big caber after all that!
You’re in excellent hands with Stefan though, and I’m looking forward to seeing some amazing images soon!
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Old 22-05-2019, 11:21 AM
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Fantastic result Paul. It seems a bloody long road.

I hoped going to OOUK from GSO would have solved your original issues.

Now Paracor or ASA corrector

Dave
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Old 26-05-2019, 04:21 AM
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Hi Paul,
there seems to be some bad press about Orion Optics UK.
https://myastroshop.com.au/ssmassey/...-10-review.htm


Here's their OOUK 3" Wynne corrector:
https://www.astroshop.eu/telescopes/...ph-ota/p,57567


and they really carry on about how good it is:
Quote:
Wynne corrector: The design of the AG corrector was determined after months of calculation and field tests with different cameras and telescopes. He is not only used in the AG models, but works so incredibly good at the telescopes of other manufacturers with other mirror sizes and aperture ratios. The corrector, which reduces the image to 0.95-fold , consists of 4 elements of special glass, arranged to two single lenses and a cemented doublet. As a result, the light from the telescope on a flat image plane of 60 mm diameter used, without color aberration. The basis of the design is the use of some rare earth glasses and the computer-aided choice of the radii of curvature of the lenses. Due to the complex construction, even world-famous astrophotographers can no longer find any mistakes in the pictures.

So - how did Mike manage to get such a good telescope? -
is he using the same model corrector?
What has changed?


cheers
Allan
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  #20  
Old 26-05-2019, 07:51 AM
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Now that makes it very clear why companies like AstroPhysics, Takahashi and a very few others can command such high prices. Their gear almost always works out of the box. Even Tak can have its focuser issues at times.

Greg.
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