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A Blog of Optical Tests

John

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John

John

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I came across this blog of an optical tester based in Austria. Many scopes and other optics are covered here from a wide variety of brands. Depends on how much interest you have in these things I guess but I found browsing though interesting anyway !:

http://interferometrie.blogspot.com/

Quite a lot of the reports and narratives are in English but some are in German.

Perhaps one for a rainy evening ?

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stuy

stuy

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Yes very interesting link, I too have spent many an hour reading herr Wolfgang Rohrs  test results on Astro foren!! 

But it doesn’t bode well for Orion optics reading the test on an Orion optics 24” poor show that ( if it is true??) But this is a well respected tester of optics , does make me wonder with accompanying test certificates of the honesty of sum telescope manufacturers 

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Ricochet

Ricochet

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The OO tale is quite a well known story and is probably one of those that contributes to the often given advice to buy second hand OO scopes of known good quality. How such an event happened I do not know, as any manufacturer individually testing and certifying their products should be able to spot problem items before they leave the factory.

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wimvb

wimvb

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Very interesting reading. Thanks for posting this, @John. I'd seen this blog before, but forgotten about it. According to the  blog, there were two similar OO incidents, one is reported in German.

The other interesting factoid is the generally excellent quality of Skywatcher ED and triplet optics. And it seems that since the blog was written, SW have taken the advice to heart and improved their products (quality of their lens cells).

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John

John

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On 20/07/2018 at 23:02, niallk said:

Next we need a 'Show Us your Interferometry Report' thread...!

They do actually have one on another forum. Oddly it's not proved that popular :dontknow:

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John

John

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On 20/07/2018 at 08:13, chiltonstar said:

Very interesting. Some interesting comments re one of the OOUK scopes!

Chris

Yes, as an OO 12" dob owner I was a bit shocked. The performance of my scope has been very good though so I'm still a happy camper but I'm not placing much worth in the paper test results that come with it !

The Synta/Skywatcher ED120 results do rather stand out in a more positive way though, as they do in Herr Rohr's tests as well. Synta got that one right :thumbright:

 

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chiltonstar

chiltonstar

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9 hours ago, John said:

Yes, as an OO 12" dob owner I was a bit shocked. The performance of my scope has been very good though so I'm still a happy camper but I'm not placing much worth in the paper test results that come with it !

The Synta/Skywatcher ED120 results do rather stand out in a more positive way though, as they do in Herr Rohr's tests as well. Synta got that one right :thumbright:

 

Yes, I think someone at OOUK might need to take action to address the comments about the OOUK dob if it is true, and if it isn't true!

The ED120 does seem to be universally (with one exception) highly acclaimed - I drool every time I look through one.

Chris

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jetstream

jetstream

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On 23/07/2018 at 02:15, chiltonstar said:

Yes, I think someone at OOUK might need to take action to address the comments about the OOUK dob if it is true, and if it isn't true!

Interesting that a couple of court systems assigned liability for the "mishap" ..... and that they needed to pay installments. Hmmm...

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John

John

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19 hours ago, jetstream said:

The description of the Tak TSA120 seems to match my observations with it. What a telescope!

Is it possible for you to indicate how much better than an ED120 Gerry ?

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jetstream

jetstream

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5 hours ago, John said:

Is it possible for you to indicate how much better than an ED120 Gerry ?

Yes, but not in a too sophisticated way John.. I notice a difference on doubles and Izar is an example. The stars are cleaner looking and this double just pops into view giving a better presentation. Overall the TSA120 is a better star splitter, the GOTO mount has opened up this facet of observing for me.  It gives a better view of Jupiter as well and same goes for lunar giving a crisper view- this scope is really sharp.

Back to stars- I have noticed that faint stars will disappear as you up the mag past a certain point, with there being a sweet spot for them. The TSA 120 will hold the stars with quite a bit more mag than the SW120ED for some reason. M13 is superb in the Tak giving views that have only come from more aperture previously.

The Tak bests the 120ED on nebula as well, not sure why.  It also shows the background sky "texture" ( dust,very faint neb etc) better along with the traditional favorites like the NAN, with very good no filter views of things.

For me a really good telescope will "grab" your attention and hold it, repeatedly giving wow moments and the TSA120 does this. It give crystal like views of the sky, it is quite amazing actually.

I must state that my SW120ED is a very good telescope.... and its getting beat.

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RobertI

RobertI

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On 19 July 2018 at 21:53, John said:

I came across this blog of an optical tester based in Austria. Many scopes and other optics are covered here from a wide variety of brands. Depends on how much interest you have in these things I guess but I found browsing though interesting anyway !:

http://interferometrie.blogspot.com/

Quite a lot of the reports and narratives are in English but some are in German.

Perhaps one for a rainy evening ?

Very interesting read, mostly as expected I guess except for the achro pretending to be a semi-apo, and the sorry tale of the OO 24". I didn't get right to the end (reading on a very slow ipad 2) but it would be very useful if he included a summary table of the results.

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rl

rl

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Does anyone know of any OO mirrors tested independently that have actually confirmed the zygo reports they issue with the more expensive mirrors? I did a quick google search and could'nt find any. It may just be a case of the problem mirrors being more newsworthy, but I'm a bit surprised at the silence on this point as there are plenty of premium refractors that independently test ok. As an owner of three 1/10 wave OO mirrors I'd feel a bit more comfortable if there was a body of evidence to say their own testing could be relied upon.  That little piece of paper is a major part of both their business model and my decision to buy....

I have to say that all three mirrors perform excellently on the sky with none of the artefacts shown in the tests on that website, but occasions to test them to their full potential are limited,  as is my ability to mentally turn diffraction rings into wavelengths!

RL

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