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Are Unitron objectives lenses bad?

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#26 oldmanastro

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Posted 21 April 2021 - 05:21 PM

 That maybe true but many amateurs pay premium prices for certain brands with the expectation they are getting exceptional  quality optics. Then they  go years believing the image they are viewing  is as good as it gets. A little bit of education on how  to test optics and now you know what your getting vs assuming.  In this thread we have seen photographic proof of both a not so great lens and ones that is. 

   There is another thread going on right now about the whereabouts of 6" Unitron. It was mentioned that one in good condition might sell for $50,000. I'm sure a buyer won't be too pleased to find out after a purchase when the optics were tested that they had issues when  the talk in the thread,  most believe it would the 'Holy Grail' of telescopes to view with.

 

                - Dave 

I guess everyone on this list has learned to test their optics in one way or another and everyone has experienced that frustrating moment when you get a substandard optic or the exhilaration of getting a top notch one. We left our assumptions behind  years ago but it was fun seeing through that first 60mm refractor thinking that it was great  even though the lenses were at most fair.

 

The $50,000 6" Unitron is a fascinating thread .I hope that it is found and the optics are great.


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#27 GreyDay

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Posted 21 April 2021 - 05:27 PM

you got to love all the added toys you can put on these refractors   Now if you get a super objective with that scope you have a real keeper you can put in the living room.

And if you don't get a super objective you're playing "pimp my Towa" :)


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#28 CHASLX200

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Posted 21 April 2021 - 06:18 PM

I have never had a bad refractor out of so many other than a Meade 7" ED.  I think the lens was fine but that darn cell before the cell fix was the problem that none of us knew about at the time i had mine. Not even Meade knew.


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#29 Bonco2

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Posted 21 April 2021 - 06:38 PM

For those that can't do a lab test on any telescope. I suggest double star tests for stars that are close to the telescope's resolving power. If you get  perfect concentric spurious disks and a thin concentric first diffraction ring and a clean view of the dim secondary, I'd say you got good optics. On a steady night do lunar and or planetary observations up at high magnification up to 80X + per inch of aperture. See how it holds up and/or where it breaks down. Might take several nights to make the evaluation but it's easy to do. I'll not deny that lab tests are the most unbiased way to evaluate. But how many of us have that as an option? For me I'm not going to invest in that but understand about those that do.

Bill


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#30 PiSigma

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Posted 21 April 2021 - 06:52 PM

you got to love all the added toys you can put on these refractors.   You can add a 40mm finder to a 128, counter weights,  clock drive,  sun screens and you have a miniature 155.  Not many scopes from other makers will do that.   Now if you get a super objective with that scope you have a real keeper you can put in the living room.

Amen to this.

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#31 CHASLX200

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Posted 21 April 2021 - 06:55 PM

Amen to this.

Now that is something i would be happy to pay well over 2k for if one local ever popped up.  Not heavy enough or big enough to be trouble to take out in a flash like my 4" was. Kinda looks like a 2.4" the more i look at it.


Edited by CHASLX200, 21 April 2021 - 06:56 PM.


#32 starman876

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Posted 21 April 2021 - 07:21 PM

And if you don't get a super objective you're playing "pimp my Towa" smile.gif

There are always objectives available and usually go for a fair price.


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#33 starman876

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Posted 21 April 2021 - 07:23 PM

Amen to this.

What a beautiful scopewaytogo.gif



#34 starman876

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Posted 21 April 2021 - 07:24 PM

Now that is something i would be happy to pay well over 2k for if one local ever popped up.  Not heavy enough or big enough to be trouble to take out in a flash like my 4" was. Kinda looks like a 2.4" the more i look at it.

it is the Unitron 2.4"  I have pimped  out a few like that.   They look so awesome.


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#35 davidmcgo

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Posted 21 April 2021 - 07:59 PM

I’m with you on the setup being annoying and needing great care to avoid getting gashed by those tips but what other 60mm refractor lets you keep a firm hand on the tripod without casing the scope to shake?

 

Fixed legs would be a bit simpler but much more difficult to store or ship.  So I’m sure that was the driving consideration.

 

Dave

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


Edited by davidmcgo, 21 April 2021 - 08:00 PM.


#36 DAVIDG

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Posted 21 April 2021 - 09:25 PM

For those that can't do a lab test on any telescope. I suggest double star tests for stars that are close to the telescope's resolving power. If you get  perfect concentric spurious disks and a thin concentric first diffraction ring and a clean view of the dim secondary, I'd say you got good optics. On a steady night do lunar and or planetary observations up at high magnification up to 80X + per inch of aperture. See how it holds up and/or where it breaks down. Might take several nights to make the evaluation but it's easy to do. I'll not deny that lab tests are the most unbiased way to evaluate. But how many of us have that as an option? For me I'm not going to invest in that but understand about those that do.

Bill

  A far better test is to use a  star test were you look at a defocus star with a green filter and using eyepiece of a  focal length that is the same or near the f-ratio of the test. The patterns on each side of focus should be the same , if they are not,  you have an issue. You can also add a central obstruction with  a simple cardboard mask so you can test it just like a Newtonian or any telescope that has a central obstruction. 

     A great book on testing refractors is old one by Taylor " The Adjustment and Testing  Telescope Objective" which has great fold out chart that shows many defocus star test images caused by defects in the lens. 

  You can view it on line https://archive.org/...ttest00cookrich

 

                          - Dave 


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#37 Terra Nova

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Posted 21 April 2021 - 10:25 PM

I’m with you on the setup being annoying and needing great care to avoid getting gashed by those tips but what other 60mm refractor lets you keep a firm hand on the tripod without casing the scope to shake?

 

Fixed legs would be a bit simpler but much more difficult to store or ship.  So I’m sure that was the driving consideration.

 

Dave

I prefer sliding legs.


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#38 RichA

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Posted 21 April 2021 - 10:41 PM

I have tested a bunch of Unitrons and found a mixed bag of  excellent, good and a few just down right bad.  One 4" lens was so bad I could not believe it.  I could not get straight DPAC lines out of that lens no matter what I did.   The old straight letter lenses are the best.

Thing about a 4 inch Unitron is, they are so costly today, they might be worth getting a regrind done if  the objective was poor.  I've only had 2 Unitrons, a 60mm and 4" and  the 4" was very good.


Edited by RichA, 22 April 2021 - 05:39 PM.

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#39 GreyDay

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Posted 22 April 2021 - 02:06 AM

There are always objectives available and usually go for a fair price.

Not here in Europe, Unitron/Polarex scopes fetch a hefty price and they're rare. I would have bought the good one i tried but my friend wanted double what i paid for my Asahi. i just couldn't do it. i could have bought the "ok" performing OTA but again it was expensive and i knew i'd have trouble locating parts to make it a complete outfit.



#40 LukaszLu

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Posted 22 April 2021 - 05:20 AM

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

Honestly, this tripod is a complete bizarre. It looks like a product based on a child's imagination about how a tripod should work. Looking at the metal spikes made of a nailed piece of galvanized sheet, you can understand why the term "Japanese car" made people laugh in those days ...

 

The worst thing is the inability to lock the legs firmly with the metal paws holding the tray. It is practically impossible to move this tripod from place to place without having to correct the position of the legs again. But it has nice thick legs and is made of beautiful wood which is worth revealing by removing the original varnish and replacing it with oil and wax.


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#41 CHASLX200

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Posted 22 April 2021 - 05:50 AM

I could never judge optics by looking at a out of focus star. Just give me Jupiter and it's moons at very high power and i will know right away if the seeing is steady. Just never had any probs with all my old school slower Newts or the high end Zambuto faster Newts.  Just that one 18" F5 Nova mirror was a dud as well as most of the SCT's i have owned and some cheaper made Newts by Celestron were not that great.

My 1960 made 4" M-152 would show M13 like no other scope in a dark sky.



#42 photiost

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Posted 22 April 2021 - 05:54 AM

  A far better test is to use a  star test were you look at a defocus star with a green filter and using eyepiece of a  focal length that is the same or near the f-ratio of the test. The patterns on each side of focus should be the same , if they are not,  you have an issue. You can also add a central obstruction with  a simple cardboard mask so you can test it just like a Newtonian or any telescope that has a central obstruction. 

     A great book on testing refractors is old one by Taylor " The Adjustment and Testing  Telescope Objective" which has great fold out chart that shows many defocus star test images caused by defects in the lens. 

  You can view it on line https://archive.org/...ttest00cookrich

 

                          - Dave 

Wonderful publication !! 

 

I was able to download a copy in PDF. 



#43 LukaszLu

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Posted 22 April 2021 - 06:26 AM

It is worth remembering that the image quality is not only the precision of the detail and the lack of defects or aberrations. What distinguishes old high "F" optics from today's "fast" refractors - even those expensive apos and low dispersion ED/fluorite lenses - are usually great contrast, natural color, very plastic ("three-dimensional") appearance of planets, etc.

 

A few days ago I described my problems with the Polarex 114 lens and attempts to overcome obvious optical flaws, which ended in a catastrophe and smashing the part of the Flint. However, the truth is that despite these drawbacks (no Newton's rings, non-axial secondary reflection suggesting a wedge-shaped abnormality in the airgap), and even despite serious Flint damage, this lens produces outstanding images of the Moon... I noticed that compared to my other 60mm lenses - even those with the greatest detail - the Polarex lens has a strange ability to reveal very dark details that remain black, invisible in other lenses. For example the earthshine is perfectly visible through the Polarex, although there was no trace of it when I compared the image with several other lenses.

 

I think these things are just as important - though they cannot be catched in standard testing.


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#44 starman876

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Posted 22 April 2021 - 06:51 AM

Wonderful publication !! 

 

I was able to download a copy in PDF. 

same here. Great to have a copy of that.  



#45 starman876

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Posted 22 April 2021 - 06:55 AM

Thing about a 4 inch Unitron is, they are so costly today, they might be worth getting a regrind done if  the objective was poor.  I've only has 2 Unitrons a 60mm and 4" and  the 4" was very good.

Near the end of Unitron sales they tried to see if they could use an Edmund objective.  They machined out the Unitron 4" cell and tried to make it fit.  It seems that a lot of people were asking for replacement objectives and the tried to provide one.  I have some of these cells.  However, I have not found and Edmund objective that would fit.


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#46 Bomber Bob

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Posted 22 April 2021 - 07:29 AM

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

Great points.  Towa's Solution:  Using a round dowel for the sliding center leg, with a tapered end, short steel spike covered with a rubber cone.  The 1960s Eagle surveyor tripod is a scaled-up version with much thicker slats & dowel...  But most important, it has a second clamp that adds stability, and cuts damping time -- even without a solid spreader.  I have the VersaGo on it, and for 3" & smaller fracs, the chain is sufficient, though I do miss an accessory tray!  Unitron should've gone that route, but they were so conservative (as in resistant to change), and/or just didn't care.  But, so did Goto with their fixed-height tripods.

 

Yes, the OP asked about Unitron objectives.  BUT... makes no sense to put a high-quality OTA on a rickety / problematic tripod.  FYI:  Of all the scope tripods I've used, the CZJ Telementor 2 was the absolute best (but, it was a surveyor tripod design!) -- adjustable & solid.  Shoot!  That EQ mount could've carried my C102 -- the 60mm OTA rode very well indeed!


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#47 Bomber Bob

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Posted 22 April 2021 - 07:35 AM

Thing about a 4 inch Unitron is, they are so costly today, they might be worth getting a regrind done if  the objective was poor.  I've only has 2 Unitrons a 60mm and 4" and  the 4" was very good.

The 1950s 152 I partially restored was one of the Deserving of a 100% Restore & Beautification samples.  But... what a BEAST.  Honestly, the only long 4" achro I'm interested in now would be a Vixen + Saturn EQ or -- even more! -- the blue Carton CST.  Either would be on a pedestal, and proudly displayed with my 6336.  [Highly unlikely, but a Dream Scope for BB:  Finding one of the RARE Meade (Towa) 400 OTAs.  I'd put it on my tall pedestal Meade StarFinder EQ.  Both would get a 100% restore, and what a display they'd make!]

 

ON TOPIC:  OP, in my experience, you can trust a Unitron lens more than Towa, but less than Astro Optical or Yamamoto.


Edited by Bomber Bob, 22 April 2021 - 07:39 AM.

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#48 starman876

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Posted 22 April 2021 - 07:40 AM

Great points.  Towa's Solution:  Using a round dowel for the sliding center leg, with a tapered end, short steel spike covered with a rubber cone.  The 1960s Eagle surveyor tripod is a scaled-up version with much thicker slats & dowel...  But most important, it has a second clamp that adds stability, and cuts damping time -- even without a solid spreader.  I have the VersaGo on it, and for 3" & smaller fracs, the chain is sufficient, though I do miss an accessory tray!  Unitron should've gone that route, but they were so conservative (as in resistant to change), and/or just didn't care.  But, so did Goto with their fixed-height tripods.

 

Yes, the OP asked about Unitron objectives.  BUT... makes no sense to put a high-quality OTA on a rickety / problematic tripod.  FYI:  Of all the scope tripods I've used, the CZJ Telementor 2 was the absolute best (but, it was a surveyor tripod design!) -- adjustable & solid.  Shoot!  That EQ mount could've carried my C102 -- the 60mm OTA rode very well indeed!

how did we get from lenses to tripods?


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#49 Bomber Bob

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Posted 22 April 2021 - 07:54 AM

how did we get from lenses to tripods?

Uh, Terra...


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#50 DAVIDG

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Posted 22 April 2021 - 07:56 AM

 Too many times I have had amateur tell me they have great optics because the image is so good in their scope yet when bench tested the optics show major problems.  Then they look through one of my scope that does have excellent optics and see what they have been missing. So in my opinion looking at the planets or the Moon can fool many that have have quality optics. Optics that test out at 1/2 wave do not produce a image that is  a fuzzy mess and won't come to focus. Most would say the image is good. A simple star test will easily show you what is really going on. 

  So going back to original question are Unitron lens bad ? The answer is some are and some are not but you have to use some type of  test that has no bias to determine that. If not it is your opinion of the image quality.

 

                  - Dave  


Edited by DAVIDG, 22 April 2021 - 08:36 AM.

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