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Are Unitron objectives lenses bad?

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#51 Wisconsin Steve

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Posted 22 April 2021 - 08:35 AM

Let's stay on topic please as we are drifting quite a bit -  Are Unitron objectives lenses bad?

 

Thanks!

 

Steve


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#52 GreyDay

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Posted 22 April 2021 - 10:04 AM

Let's stay on topic please as we are drifting quite a bit -  Are Unitron objectives lenses bad?

 

Thanks!

 

Steve

A less than favourable Unitron review : http://www.scopeview.../Unitron114.htm

 

"By the time you’ve upped the power to 100x with the 9mm Orthoscopic (‘Sym’), the Model 114 has gone all soft and you know it won’t take much more. The Unitron just won’t take my 7mm Takahashi MC orthoscopic"

 

To put that statement into perspective I regularly use a 7.5mm haloween plossl on all of my 60mm scopes with no issue, on occasion i'll use a 6mm BCO or the Bertele B6mm that came with the pentax. All of my 50mm Towas will easily do 120x so you have to wonder what went wrong with some of these Unitrons?


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#53 starman876

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Posted 22 April 2021 - 10:23 AM

A less than favourable Unitron review : http://www.scopeview.../Unitron114.htm

 

"By the time you’ve upped the power to 100x with the 9mm Orthoscopic (‘Sym’), the Model 114 has gone all soft and you know it won’t take much more. The Unitron just won’t take my 7mm Takahashi MC orthoscopic"

 

To put that statement into perspective I regularly use a 7.5mm haloween plossl on all of my 60mm scopes with no issue, on occasion i'll use a 6mm BCO or the Bertele B6mm that came with the pentax. All of my 50mm Towas will easily do 120x so you have to wonder what went wrong with some of these Unitrons?

you need to view through one that has good optics.  I have had dozens of 114 and 128 unitrons and only a few had lenses that were not very good.   The Unitron lenses were not always made by the same shop.  Nihon Seiko subcontracted everything out.  The very early Unitrons all had good lenses.  They were made by craftsman that were left over from WWII.  As they retired new lens makers opened up shop.  Some of those shops were nowhere near the quality that the early shops were.    Have you checked your lense to make sure it is adjusted properly in the cell?


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#54 ccwemyss

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Posted 22 April 2021 - 11:01 AM

A less than favourable Unitron review : http://www.scopeview.../Unitron114.htm

 

"By the time you’ve upped the power to 100x with the 9mm Orthoscopic (‘Sym’), the Model 114 has gone all soft and you know it won’t take much more. The Unitron just won’t take my 7mm Takahashi MC orthoscopic"

 

To put that statement into perspective I regularly use a 7.5mm haloween plossl on all of my 60mm scopes with no issue, on occasion i'll use a 6mm BCO or the Bertele B6mm that came with the pentax. All of my 50mm Towas will easily do 120x so you have to wonder what went wrong with some of these Unitrons?

Hard to know without context, but that sounds like a classic case of the elements being backwards in the cell. Did the reviewer check them?

 

Chip W. 



#55 DAVIDG

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Posted 22 April 2021 - 11:02 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 


Edited by DAVIDG, 23 April 2021 - 09:04 AM.

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#56 GreyDay

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Posted 22 April 2021 - 11:02 AM

you need to view through one that has good optics.  I have had dozens of 114 and 128 unitrons and only a few had lenses that were not very good.   The Unitron lenses were not always made by the same shop.  Nihon Seiko subcontracted everything out.  The very early Unitrons all had good lenses.  They were made by craftsman that were left over from WWII.  As they retired new lens makers opened up shop.  Some of those shops were nowhere near the quality that the early shops were.    Have you checked your lense to make sure it is adjusted properly in the cell?

I don't own one, but i have tried two.. look at post #6 on page one.

 

The "good" one i tried performed well, the second wasn't as sharp, noticeably less sharp!. i star tested them and in both the rings were round no pinching or collimation issues but the rings were not well defined on the second scope. As i said earlier the good scope i'd have bought if it hadn't been so expensive. I like Unitrons, look good, well built you can spend a lifetime collecting all the accessories if thats your thing. The second scope i was offered as an OTA only was the right price and in good condition, I'd have bought it if it had performed as well as the first one... but it didn't!.  It was soft at high mag, a Kenko 60x910 i compared it with was sharper and had more contrast using the same diagonal and ep's. That's why i still don't have a Unitron.


Edited by GreyDay, 22 April 2021 - 11:05 AM.


#57 Bomber Bob

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Posted 22 April 2021 - 11:22 AM

Nihon Seiko subcontracted everything out.  The very early Unitrons all had good lenses.

 

- What are the odds that the 2 x 1950s Unitrons that I bought randomly & years apart were above-average?  IOW:  It points to consistent quality / reliability during that time period.

- 1950s Edmund 3" & 4" refractors are excellent to outstanding.  The objectives were made in Japan (possibly Carton).

- Even Towa sourced from the better / experienced makers in the 1950s & 1960s, and the ones I've tested (mostly 60x800s) had reliable quality.

- Like other importers, Unitron lost some of those makers, such that they looked at adapting Edmund objectives to their OTAs.

 

IOW:  OP, buy a 1950s Unitron, and you have the best shot at an excellent or better sample.


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#58 clamchip

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Posted 22 April 2021 - 01:49 PM

If you go about half way down the page to "Nihon Seiko' you will see it

noted the 4 inch objectives came from many sources:

http://home.europa.c...ope/tsjapan.txt

 

Robert


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#59 starman876

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Posted 22 April 2021 - 02:38 PM

If you go about half way down the page to "Nihon Seiko' you will see it

noted the 4 inch objectives came from many sources:

http://home.europa.c...ope/tsjapan.txt

 

Robert

I rest my case


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#60 Terra Nova

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Posted 22 April 2021 - 04:16 PM

how did we get from lenses to tripods?

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#61 CHASLX200

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Posted 22 April 2021 - 06:18 PM

A less than favourable Unitron review : http://www.scopeview.../Unitron114.htm

 

"By the time you’ve upped the power to 100x with the 9mm Orthoscopic (‘Sym’), the Model 114 has gone all soft and you know it won’t take much more. The Unitron just won’t take my 7mm Takahashi MC orthoscopic"

 

To put that statement into perspective I regularly use a 7.5mm haloween plossl on all of my 60mm scopes with no issue, on occasion i'll use a 6mm BCO or the Bertele B6mm that came with the pentax. All of my 50mm Towas will easily do 120x so you have to wonder what went wrong with some of these Unitrons?

 

 

A less than favourable Unitron review : http://www.scopeview.../Unitron114.htm

 

"By the time you’ve upped the power to 100x with the 9mm Orthoscopic (‘Sym’), the Model 114 has gone all soft and you know it won’t take much more. The Unitron just won’t take my 7mm Takahashi MC orthoscopic"

 

To put that statement into perspective I regularly use a 7.5mm haloween plossl on all of my 60mm scopes with no issue, on occasion i'll use a 6mm BCO or the Bertele B6mm that came with the pentax. All of my 50mm Towas will easily do 120x so you have to wonder what went wrong with some of these Unitrons?

My best refractors could take a 3mm and Barlow and still look good with the Taks and TMB. My 4" Unitron from 1960 did 400x fine.  Deep sky just looked so good in that scope in a dark sky.  M22 with a dark sky back ground and tiny little stars to the core.


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#62 godelescher

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Posted 22 April 2021 - 06:31 PM

Just wanted to say thanks for all the responses. I consider this question very well answered. It seems like there is somewhere between a 5 and 15% chance a unitron objective is less than ideal. I thought bomberbob put it pretty succintly saying he's had worse odds with Towa and better odds with Royal Astro.

 

I've never looked through a Unitron, so I don't know. I think I'd like to see what all the fuss is about with the apparently outstanding mechanical build of the mounts and hardware. I'm a total sucker for good mechanical builds. I'd heard it mentioned on several occasions that people were unhappy with the optics, so that made me pause.

 

I'd like to find a nice Unitron to buy, "but," I thought, "if the optics aren't there, should I bother?" Anyway, that's how I came to ask this question; trying to decide if I should chase a Unitron.

 

At this point I'm just enjoying the conversation, whether it evolves into tripods or whatever else, it's fun to read. Thanks.


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#63 CHASLX200

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Posted 22 April 2021 - 06:45 PM

Even if the optics are not great it is so nice to look at.


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#64 Terra Nova

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Posted 22 April 2021 - 06:53 PM

The 1950s 2.4”, 3”, and 4” Unitron’s I had were definitely the best.


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#65 Terra Nova

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Posted 22 April 2021 - 06:58 PM

Well since the OP has opened up the topic, I like the old brass engraved block-lettered Unitron eyepieces too! I have a full collection and they’re quite good. I was always particularly partial to the 9mm and 7mm Symmetricals. I also have the 4, 5, and 6mm orthos and they’re quite nice on double stars.

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#66 Defenderslideguitar

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Posted 22 April 2021 - 07:07 PM

I resist the urge to stray off topic and mention the golden age of the 1950's for the best quality made Gibson Fender Martin guitars.....but maybe there is something about the 50's to 1960 Unitrons that bring  more consistent quality optics   as described above.......

 

This topic has spread some education around that I and perhaps others benefitted from.....also puts a premium on buying from someone trusted and in the know

 

Coming to a classified section near you soon......:

 

WANTED:   1950's Unitron  


Edited by Defenderslideguitar, 22 April 2021 - 07:08 PM.

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#67 Terra Nova

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Posted 22 April 2021 - 07:11 PM

Out of a half dozen or so Unitron’s up to 4”, the single one that ai have settled on to keep is my circa 1955-56 62mm model 114.


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#68 John Rose

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Posted 22 April 2021 - 07:13 PM

The first Explore Scientific refractor I ever saw and looked through was disappointing. Really disappointing. An AR102. The AR and ED ES scopes I have seen since have been really good. Of the first four Stellavue refractors in my area, two were really nice. The other two were really disappointing.

 

My 4" Unitron is really nice. According to the Unitron sticker adddress inside the box it is no newer then early 1956. It compares favorably with a Parallax 4" F15 with a Research Grade Vixen objective. The focuser on that scope is far better!

 

A friend has a 4" Unitron. It is really disappointing. Was it always so? Or did some thing happen to it? Like a previous owner took apart the objective to clean it and misassembled it? I have seen a large refractor objective dissasembled and it had 6 spacers instead of three and the alignment marks were no where near each other. The previous work had been done by a "professional optician".  So  I am not in a hurry to blame the manufacturer of old scopes.

 

Richard Buchroeder in an issue of The Amateur Telescope Makers Journal described a 4" Unitron as abominal. He was lucky and aquired a Zeiss lens to replace it with.

 

I have a Unitron 114 which has very nice optics. It had been left in a barn for at least twenty years according to the seller.  Pretty good overall condition.

 

I believe that like most scopes today, most of them were good or better and there were some poor ones.

 

John


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#69 GreyDay

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Posted 22 April 2021 - 07:17 PM

I'd like to find a nice Unitron to buy, "but," I thought, "if the optics aren't there, should I bother?"

I get this... If a scope has average optics it would spend most of it's time in the house instead of under the stars. In a way it's the same reason that i haven't bought a Takahashi or other good quality ED, because i know when i do it'd be my scope of choice and my classics would end up being unused.


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#70 LukaszLu

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Posted 23 April 2021 - 05:54 AM

I get this... If a scope has average optics it would spend most of it's time in the house instead of under the stars. In a way it's the same reason that i haven't bought a Takahashi or other good quality ED, because i know when i do it'd be my scope of choice and my classics would end up being unused.

Not necessarily. I have just made my first photographic attempts with the RAO R-74 (76 m). I compared them with the image obtained from the 120 ED refractor and of course they give way a bit, but not much. I think if I compared this classic RAO with a modern apo or ED with the same 76mm diameter, RAO would eat this modern, expensive equipment for breakfast and still be hungry ...


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#71 starman876

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Posted 23 April 2021 - 10:37 AM

Not necessarily. I have just made my first photographic attempts with the RAO R-74 (76 m). I compared them with the image obtained from the 120 ED refractor and of course they give way a bit, but not much. I think if I compared this classic RAO with a modern apo or ED with the same 76mm diameter, RAO would eat this modern, expensive equipment for breakfast and still be hungry ...

I agree with the this completely.


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#72 rcwolpert

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Posted 23 April 2021 - 12:58 PM

I agree with the this completely.

I also agree with “not necessarily”. I had my Mayflower 816 (APL) set up near some Taks and other scopes at a public event looking at a multiple transit on Jupiter and I heard several comments during the night that the 816 gave the best views. After making my rounds to check out the other scopes, I had to agree. So maybe the phrase should be “generally but not necessarily”.


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#73 Bomber Bob

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Posted 23 April 2021 - 01:27 PM

I also agree with “not necessarily”. I had my Mayflower 816 (APL) set up near some Taks and other scopes at a public event looking at a multiple transit on Jupiter and I heard several comments during the night that the 816 gave the best views. After making my rounds to check out the other scopes, I had to agree. So maybe the phrase should be “generally but not necessarily”.

Yeah, I agree.  Lots of subjectivity involved.  Good as my 1950s Unitron 3" & 4" F15 achros were, both had visible CA that wasn't visible in my Vixen FL80S (F8 fluorite doublet) and AT102ED (F7 ED doublet); and, there's no denying that these inherent defects in traditional achromatics have some "blurring" of the image at the eyepiece.  IOW:  Even if you don't see much false color in your Unitron, damage has been done to some degree.  But... CA doesn't keep me from using my F11 C80 & C102 achros; or, my workhorse Dakin 4" F10.  My Tak FC-50 F8 fluorite edges past my Swift 838 F14 50mm, but the Swift lens is so well made, and the final views are so pleasing to me, that I kept it -- while I sold both the Vixen & AT APOs...


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#74 LukaszLu

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Posted 23 April 2021 - 04:18 PM

I mentioned my comparisons regarding these photos because it is beyond dispute for me that classic optics with a high "F" beats many modern low dispersion lenses in visual observation. The color, contrast, naturalness and three-dimensional feel of the RAO R-74 are incomparably better than what my modern 120mm ED gives. However, it always seemed to me that the superiority of low-dispersion lenses and larger diameters is immediately visible in the case of computer-aided photography, which allows you to pick out details that remain elusive to the eye. I saw this as one of the reasons for the disappearance of long refractors from the market, which coincided with the advent of digital photography.

 

It turns out that even this advantage of modern large-diameter optics is not so obvious. Even the aforementioned chromatic aberration - although, for example in an ED lens, it may not be immediately visible during visual observations, it might be still visible in the photos. In both the RAO and SW 120ED images, a yellowish discoloration is visible at the edge of the Moon's disc, perhaps slightly weaker in ED, but still present. Compare CA in the Mare Australe area:

- 76 mm RAO: https://www.cloudyni...ing/?p=11051892
- 120 mm ED https://www.cloudyni...lor-2020-02-20/


Edited by LukaszLu, 24 April 2021 - 07:58 AM.

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#75 RichA

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Posted 24 April 2021 - 12:56 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 is the key when it comes to old scopes, true.  Whereas I once  tested dozens of ETX90's and they all tested virtually the same. 




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