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Are Unitron objectives lenses bad?

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#76 RichA

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Posted 24 April 2021 - 01:23 AM

 Here is the problem , when someone states that a scope can take XYZ power that is ones opinion if the image is good. No disrespect to anyone but that is not a valid indication of optical quality, it is a  personnel judgment.  Also there can be  a simple  reasons as to  why an image degrades at high power so the optics might be fine.  I can't count how many eyepieces I have found that at one point were disassembled and put back together wrong. Again they still form an image just one that  as a  good as it could be. I have seen objectives  that were backwards  in the cell for years and people of said the image was great !  It took me a few minutes to find the problem and another few to fix it. The result was a telescope that now gave an image that it should have. I can't stress enough it is not difficult to test optics. Many tests  like checking  the proper alignment of the air space just requires placing  the lens under a common CFL bulb and observing the pattern of the interference fringes.   Correctly done star testing  and/or bench testing removes the bias and you get the real quality of the optics. 

   The other thing that many don't appreciate is how variable figuring optics actually is. It is not like machining parts were one can make millions of them to tight tolerance. Glass and pitch act differently all the time. Go up into the ATM Forum and see the issue people have in figuring optics. Modern day technique can get SOME optical designs  to 1/2 to 1/4 wave almost all the time without any need to test but others require testing, correcting, testing etc to get them to at least 1/4 wave  if not better. That is using modern techniques but we are talking about optics made 60 years ago so the variability can be much greater.  

 

                - Dave 

Variability when people push glass in their basement by hand, or use crude grinding machines, primitive manual spherometers, techniques culled from ancient texts to make telescopes.  But machines make most of the average optics today do it start to finish with no human hand contact and with reasonable and consistent results.  The problem in those days was that they only had "X" amount of time to produce a lens and maintain a profit and not all makers had the skill, apparently.


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#77 LukaszLu

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Posted 24 April 2021 - 05:29 AM

The lack of repeatability in optics is not necessarily the result of manual work and primitive devices. All you need is weaker material and failure to comply with costly technological regimes. It is enough that someone decides to do something faster - because it means cheaper. Glass heats up during processing - and as it heats up, it also changes its size and geometry. This effect alone creates problems with obtaining repeatable geometry. Add to that the issues related to the quality of glass, its proper annealing, etc. - and you will have a whole host of reasons why optics made without human intervention, on the best computerised devices, will not be repeatable.


Edited by LukaszLu, 24 April 2021 - 07:59 AM.

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#78 DAVIDG

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Posted 24 April 2021 - 08:40 AM

"  ,,,,,.,and you will have a whole host of reasons why optics made without human intervention, on the best computerised devices, will not be repeatable."

   Exactly ! That understanding comes when you have actually made optical surface .Pitch and glass do not act the same all  the time  I personally know the  Master Opticians that made the corrective optics for the Hubble, the ones in the camera on the New Horizon missing to Pluto and the ones in the IR camera on the Voyager mission and the finally figuring was done by hand  not machine. They tested, corrected by hand and tested again.  So those "crude" methods are still the ones used today to make precision optics.  Cumberland who makes the optics for Questar still hand corrects the final figure on their optics. It takes time and that cost money so you get what you pay for.

   I 100% agree that time is money and optics need to made in a time frame that a profit can be made. What this lead to is what I have been trying to get  amateurs too understand, that is the quality of the optics in their scope is the most variable parts not the least. It has been my experience being in this hobby for 40+ years now,  that many amateurs assume that they are always getting high quality optics and never question that. If the images doesn't live up to expectation it has to be some other reason like the eyepiece, seeing, the need for  $300 focuser, a $1000 carbon fiber tube,  etc. 

  So getting back to the point of this thread is that many people buy Unitron's because they believe  they are getting an excellent mechanical scope which I agree they are, and along with that,  excellent optics. When the theory about the optical quality is  challenged that  turns out that may  not be the case. 

    It maybe true that the odds of getting a good optics in an Unitron made in the 1950's is better then others but it is not a given so learn to test optics so you know what your buying. It is not hard to star test a refractor correctly using an eyepiece that gives the correct magnification  and using a green filter or  an optical flat or pan of oil to double pass autocollimation. Then you know what your paying for and better yet know the image will be what you expect.

 

                       

 

                - Dave 


Edited by DAVIDG, 24 April 2021 - 09:43 AM.

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#79 ccwemyss

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Posted 24 April 2021 - 03:26 PM

and you will have a whole host of reasons why optics made without human intervention, on the best computerised devices, will not be repeatable.

Machine made optics are quite repeatable. But it depends on the tolerance and distribution function you use to define repeatability. It's fairly easy to machine manufacture optics within 1/2 wave, which is probably fine for eyeglasses. There is no technological reason that prevents telescope manufacturers from mechanically turning out 1/20th wave optics. For example, semiconductor manufacturing regularly works with tolerances of a few nanometers. But it also costs $15B to build a chip fabrication plant.

 

The issue is that the telescope market, which is small, doesn't support the cost. The manufacturers do get to take advantage of the advances in optical fabrication equipment that larger markets develop. But even then, beyond a certain tolerance, the costs hit a knee in an exponential curve, where calibration, purity/quality of materials, and other factors combine. So, considering the price sensitivity of the majority of customers, they set the tolerances at a level that they can hit pretty consistently with a reasonably narrow distribution, while generating enough profit to easily cover the cost of returns when a unit is on the low end of the curve and the customer is knowledgable enough to recognize it. By their definition, they are achieving repeatability. 

 

With Unitrons, we see variation because of changes in Nihon-Seiko's sources, and also changes in quality from sources over time, as well as unit-to-unit variations within sources at a given time. Just as hand-figuring can consistently produce excellent optics, it can also produce greater variability. It's clear that Unitron didn't enforce strict tolerance standards on their objectives throughout their history. Because of their definition (or lack of definition) of repeatability, we end up answering the the original question by saying, "No, some are quite good. But there is no sure fire way to know unless you test them."

 

Chip W. 


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#80 LukaszLu

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Posted 24 April 2021 - 04:13 PM

I am not a specialist in this field, but it seems to me that the part of the problems that arise from material issues, such as glass annealing, may appear after many, sometimes even several dozen years. This effect also contributes to making modern optics seem more reproducible. The question is how this modern optics will look like in 50 years ...


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#81 grif 678

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Posted 24 April 2021 - 06:01 PM

I still think the folding tripods on the 60mm and 75mm models suck! Both eq. and alt-az. They are a cheap, half-a$$ design. And don’t even get me started on the pointy feet! If you don’t loose an eye with that spike or wind up with a fencing scar on your cheek while swinging the lower leg member out to unfold it, you’re sure to tear up your floor if you attempt to set it up indoors without shielding the tips! I really hate Unitron tripods! Plus, with their fixed length and locking spreaders there is no way to make allowances for sloping uneven surfaces unless you set up on a freshly tilled field or recently watered lawn. It’s just cheap! That’s the only reasonable explanation of its adoption over sliding legs. angry.png

I totally agree with Terra. I have two small scopes mounted on unitron 114 mounts ( the best available altaz mounts), but both mounts have vixen sliding wooden legs.


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#82 Bomber Bob

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Posted 25 April 2021 - 07:59 AM

I know a lot of people absolutely love unitron mounts and mechanicals, but how are the views? I've never looked through a unitron, but I've heard mixed reviews

As you can see from the posts, your odds of getting a decent Unitron OTA are good.  Your odds of getting an excellent / outstanding Unitron mount are near 100%.  My ASTRO, Edmund, & Goto fracs had better optics, but only my Goto had a competitive mount -- in the 1950s age group of my Unitrons (gotta keep it Fair!).

 

I seriously considered putting my Uni 142 EQ on a pedestal, and using my Sears (AO) OTA on it -- perfect combo!  (Even now, when I want to use high-power on my fracs for observing or imaging, I use my tall pedestal Meade StarFinder EQ.)  A motorized 142 / 152 EQ on a 4" or larger diameter tall pedestal would be near-perfect for regular use, and could be made to be a beautiful Display, too.

 

Still, there's something about Unitrons as delivered (like my circa 1955 Model 142):

 

Unitron 142 S13 (Complete spectros 35mm Accessories).jpg

 

A Bonus for BB:  It accepted my spectros Big Prism & Big Kellners with 35mm barrels - talk about opening up the throttle!


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#83 Terra Nova

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Posted 25 April 2021 - 09:21 AM

I totally agree with Terra. I have two small scopes mounted on unitron 114 mounts ( the best available altaz mounts), but both mounts have vixen sliding wooden legs.

As much as I like sliding legs and dislike folding legs terminating with deadly weapons, I’m a purist and have the original legs with the original mount with the original cradle with the original OTA. For practical use however, I also have a set of hinged rings that fit the 114 tube, attached to a Vixen/ADM rail. I often use the 114 OTA on either my Vixen Porta II alt-az mount or my C-Omni CG-4 equatorial mount. It’s a wonderful setup to compliment the great optics.



#84 steve t

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Posted 25 April 2021 - 09:22 AM

Someone please correct me if I'm wrong, but back in the late 1970's or early 1980's there were whispers of a famous telescope maker, located in northern Illinois, that had refigured the objective of a few 4" Unitrons. I may just be repeating an old urban  legend, but if true...


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#85 Terra Nova

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Posted 25 April 2021 - 09:30 AM

Someone please correct me if I'm wrong, but back in the late 1970's or early 1980's there were whispers of a famous telescope maker, located in northern Illinois, that had refigured the objective of a few 4" Unitrons. I may just be repeating an old urban  legend, but if true...

Roland Christian?


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#86 clamchip

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Posted 25 April 2021 - 10:47 AM

I always thought my Unitron 150 with Tinsley mounting was one of the prettiest

telescopes I ever owned.

Robert

 

post-50896-0-05129200-1521729185.jpg


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#87 photiost

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Posted 25 April 2021 - 04:25 PM

...

 

I seriously considered putting my Uni 142 EQ on a pedestal, and using my Sears (AO) OTA on it -- perfect combo!  (Even now, when I want to use high-power on my fracs for observing or imaging, I use my tall pedestal Meade StarFinder EQ.)  A motorized 142 / 152 EQ on a 4" or larger diameter tall pedestal would be near-perfect for regular use, and could be made to be a beautiful Display, too.

 

...

 

I often use my RAO Tasco model 7TE with the spare Unitron 114 mount - what a great combination.


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#88 godelescher

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Posted 25 April 2021 - 05:21 PM

I always thought my Unitron 150 with Tinsley mounting was one of the prettiest

telescopes I ever owned.

Robert

 

attachicon.gifpost-50896-0-05129200-1521729185.jpg

It's just... elegant. It's quiet and simple and right.


Edited by godelescher, 25 April 2021 - 05:22 PM.

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#89 grif 678

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Posted 25 April 2021 - 08:35 PM

Even though some of the unitron objectives may be bad, they had to be considered  great scopes due to the craftsman ship, the mounts, but probably not a lot on the folding legs. Unitron really knew how to build up one's excitement with the two page ads they had, showing all the scopes they had. Each scope had it's eyepieces, powers, and all listed in the ads. I still like looking at those ads, brings back many memories, even though I never had a unitron scope, have several mounts for my refractors and my ETX.


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#90 ALman

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Posted 26 April 2021 - 12:31 AM

It's hard to rate scopes of this age as quality maintenance over the years is critical to their care. The uniron objectives I have come across over the years seem pretty OK. Dave Trott is a guy that would know for certain.


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#91 Terra Nova

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Posted 26 April 2021 - 06:54 AM

It's just... elegant. It's quiet and simple and right.

That’s what I love about Al Nagler’s introduction of the Genesis and Renaissance 4” apos on their Gibralter mounts and wooden tripods. He got back to that simple elegance of the classics of a bygone age which ironically now have become classics themselves.

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#92 starman876

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Posted 26 April 2021 - 08:03 AM

Someone please correct me if I'm wrong, but back in the late 1970's or early 1980's there were whispers of a famous telescope maker, located in northern Illinois, that had refigured the objective of a few 4" Unitrons. I may just be repeating an old urban  legend, but if true...

first time I have heard this rumor.  


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#93 Terra Nova

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Posted 26 April 2021 - 09:44 AM

first time I have heard this rumor.  

I have no idea if it’s true but I’ve heard it at least once. I’ve also heard Barry Griner of D&G has ‘fixed’ a couple over the years. 


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#94 DAVIDG

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Posted 26 April 2021 - 01:30 PM

I have no idea if it’s true but I’ve heard it at least once. I’ve also heard Barry Griner of D&G has ‘fixed’ a couple over the years. 

 Well, when I visited D&G optics when Barry refigured the 4" Clark objective for  our scope at Mt Cuba  ( Yes  there are bad Clarks too !)  he placed a 3" Unitron  objective on the test stand and showed me how bad it was. It had zones and a turned edge.  There is also an thread in the ATM section were a 4" was refigured that I help provide guidance on  https://www.cloudyni...a-4-fraunhofer/

So again there is actual data out there  from a number of difference source that some of these Unitron objectives weren't the best. 

 

             - Dave  


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#95 starman876

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Posted 26 April 2021 - 02:26 PM

 Well, when I visited D&G optics when Barry refigured the 4" Clark objective for  our scope at Mt Cuba  ( Yes  there are bad Clarks too !)  he placed a 3" Unitron  objective on the test stand and showed me how bad it was. It had zones and a turned edge.  There is also an thread in the ATM section were a 4" was refigured that I help provide guidance on  https://www.cloudyni...a-4-fraunhofer/

So again there is actual data out there  from a number of difference source that some of these Unitron objectives weren't the best. 

 

             - Dave  

Yes, some were not good.   Unitron did not have a test stand.  The only thing they checked were for newton rings.   I think in the later years they stopped checking for that.   It was a shame they did not test their lenses.  I wonder what manufacturers did test their lenses before they were shipped to the USA?



#96 DAVIDG

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Posted 26 April 2021 - 08:19 PM

Yes, some were not good.   Unitron did not have a test stand.  The only thing they checked were for newton rings.   I think in the later years they stopped checking for that.   It was a shame they did not test their lenses.  I wonder what manufacturers did test their lenses before they were shipped to the USA?

  The question is why didn't they test them ? It is not hard as I have shown. My conclusion is that most amateurs just assume that they where getting excellent optics and when there is an issue it something else and not the optics. So manufactures were able to sell optics that greatly varied in quality because no one was challenging them and asking for their money back. 

    There are many small telescopes and binoculars I have seen that have a "Passed  Japanese Optical Institute" sticker on them. When I have tested them they are usually very good. I have a 80mm Selsi with one of those stickers and the lens tests near perfect in Double Pass. So some one was testing the optics coming out of Japan to give US consumers some confidence in the products being imported.  

 

              - Dave 


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#97 CHASLX200

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Posted 27 April 2021 - 06:19 AM

That’s what I love about Al Nagler’s introduction of the Genesis and Renaissance 4” apos on their Gibralter mounts and wooden tripods. He got back to that simple elegance of the classics of a bygone age which ironically now have become classics themselves.

Never had a TV scope.  If they are as good as a Tak then i would love them.


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#98 starman876

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Posted 27 April 2021 - 08:35 AM

  The question is why didn't they test them ? It is not hard as I have shown. My conclusion is that most amateurs just assume that they where getting excellent optics and when there is an issue it something else and not the optics. So manufactures were able to sell optics that greatly varied in quality because no one was challenging them and asking for their money back. 

    There are many small telescopes and binoculars I have seen that have a "Passed  Japanese Optical Institute" sticker on them. When I have tested them they are usually very good. I have a 80mm Selsi with one of those stickers and the lens tests near perfect in Double Pass. So some one was testing the optics coming out of Japan to give US consumers some confidence in the products being imported.  

 

              - Dave 

does anyone know what the "Passed Japanese Optical Institute" Means?  Like what kind of test was done?  What was the Japanese Optical Institute?


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#99 steve t

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Posted 27 April 2021 - 12:05 PM

Of the main things I've learned, by reading the posts from the experts on this forum, is that the saying "in god I trust, everyone else bring data" is very valid.smile.gif


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#100 SandyHouTex

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Posted 27 April 2021 - 10:25 PM

I would be livid if I plopped down $50,000 for a 6 inch Unitron and the lens really sucked.




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