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Zeiss Coudé telescope rebfurbish

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#51 Peter Ceravolo

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Posted 23 January 2019 - 11:45 AM

Small question: I won't be at the observatory for the next few days, but the housing, is that made of aluminium or steel?

The only things that I can recall being made of aluminum are the large bearing cages to keep the balls apart. Everything is steel and weights a million pounds... :-)



#52 Peter Ceravolo

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Posted 24 January 2019 - 02:07 AM

Today I had a look at the Zeiss synchronus drive the "SYNFA 1".

 

I'm an optics guy, I push glass, but I do pretend to know something about mechanics. When it comes to electronics, I plug it in and pray that it works.

 

I'm scared....

 

I'm interested in preserving as much of the original Zeiss equipment as possible, but I suspect if anything in this mass of electronic stuff blows the whole unit is toast.

Ultimately the plan is replace the classic drive with a modern servo system.

 

IMG_9228.JPG

 

IMG_9230.JPG

 

IMG_9249.JPG

 

IMG_9247.JPG

 

IMG_9248.JPG


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#53 Peter Ceravolo

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Posted 24 January 2019 - 02:22 AM

Here is a drawing of the system from the manual.

 

Synfa.jpg


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#54 Peter Ceravolo

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Posted 24 January 2019 - 02:24 AM

And a shot of the insides.

 

IMG_9244.JPG


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#55 mikerepp

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Posted 24 January 2019 - 07:37 AM

Just a suggestion, it looks like you may have some electrolytic capacitors in the circuit.   If you plug it in directly to 110V they may leak if they have not seen any voltage in a while.  Plug it into a variac with the voltage at a very low setting and over a day or so bring the voltage up gradually.   This will allow the caps to "regenerate" and not go bad.   Its not a guarantee but I have used this method with success on old radios.

The relays should be fine, they may need the contacts burnished.  You can use a business card to burnish the contacts.  Place it between the contacts with some slight pressure closing them on each side of the card.  Pull the card back and forth to clean the contacts. If they are really bad a burnishing tool will help.  Don't file the contacts some contacts are made with layers of different materials the file will destroy them.  I was an engineer for a relay company many years ago.  Burnishing tools were verboten but all of us had them. flowerred.gif


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#56 Benach

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Posted 24 January 2019 - 08:20 AM

mikerepp: can you show me a picture of a burnishing tool? I am not native English and I don't know what kind of tool you mean.


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#57 mikerepp

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Posted 24 January 2019 - 09:36 AM

Capture.JPG

 

Here is an example.  Very thin piece of metal with a very fine abrasive.   As I said a business card will usually take care of any tarnish or residue on the contacts.  Hope this helps.



#58 Peter Ceravolo

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Posted 24 January 2019 - 11:25 AM

Just a suggestion, it looks like you may have some electrolytic capacitors in the circuit.   If you plug it in directly to 110V ..

Thanks Mike, I wish you were next door!

 

You're probably familiar with the "Dirty Harry Dictum"... " A man's gotta know his limitations"... :-)

 

The opto-mechanical work for the Zeiss refurb is fairly straight forward for me to handle. But in the interest of not pouching what is probably still working, I'm going to leave the drive alone, not plug it in. I'm hoping that I'll find someone with the right skill sets to refurb the electronics.


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#59 RalphMeisterTigerMan

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Posted 25 January 2019 - 12:18 AM

I remember viewing through this particular telescope many times, before the .5 metre Cassegrain replaced it. Even though the views were quite impressive, it looked really small in the middle of that massive dome.

 

I'm curious, was the Zeiss bino-viewer also included with the telescope?

 

RalphMeisterTigerMan



#60 Benach

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Posted 25 January 2019 - 02:58 AM

I'm curious, was the Zeiss bino-viewer also included with the telescope?

 

In our case, it was. Pity it only accepts 0.965" eyepieces. Not sure if Peter has one.



#61 Kokatha man

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Posted 25 January 2019 - 04:01 AM

...as an addendum to Mike's comments, older electrolytic capacitors/condensors (I think I can see several in the above images btw) usually have a paste as the electrolyte...these dry out over time & as he says, one of the most common fault in old electronic gear is these failing due to aforesaid.

Burnishers came in all types from those with an abrasive coating to those that resembled a flat piece of thin, hardened steel with a very finely dimpled surface like a very fine file, best for avoiding damage to the contacts per se...we used these on the old Siemens relays in telephone exchanges before crossbar which was then replaced by fully digital switching finally...

I had not heard of the "regeneration" technique Mike mentions but at the very least all circuitry should be examined physically & components such as capacitors etc tested for shorts etc.

Enjoying both threads on these scope btw! smile.gif

#62 mikerepp

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Posted 25 January 2019 - 08:44 AM

kokatha man,  I was shown that variac trick by an old time ham operator.   He went back to the early days of ham radio.  Very smart guy.  I was a 3rd class radio operator working as a DJ in a local am radio station back then.   We were working on the transmitter one night trying to eliminate a spurious harmonic.  We were working with the manufacturer over the phone and were really having a time of it.  Mr B. had heard us on the air and drove out to the station just to check it out.  After hours spent with the manufacturer he knew in 30 minutes how to fix it.  We replaced a crystal oscillator that the manufacturer swore  would never go bad no more issues.

Just remember when cleaning the contacts, less is better.  Silver cadmium contacts can be ruined with too much burnishing.  Once relay contacts are clean and functioning the contacts will stay clean thru use.


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#63 Peter Ceravolo

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Posted 25 January 2019 - 01:00 PM

I remember viewing through this particular telescope many times, before the .5 metre Cassegrain replaced it. Even though the views were quite impressive, it looked really small in the middle of that massive dome.

 

I'm curious, was the Zeiss bino-viewer also included with the telescope?

 

RalphMeisterTigerMan

 

Yes the telescope does not have the visual wow factor of a straight through tube. Below is a pic of the instrument in the Vancouver observatory.

My Zeiss does have a pile of accessories in various states of repair. I'll post pics later.

 

Zeiss telescope 2 small.jpg


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#64 JohnH

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Posted 25 January 2019 - 01:39 PM

Just a suggestion, it looks like you may have some electrolytic capacitors in the circuit.   If you plug it in directly to 110V they may leak if they have not seen any voltage in a while.  Plug it into a variac with the voltage at a very low setting and over a day or so bring the voltage up gradually.   This will allow the caps to "regenerate" and not go bad.   Its not a guarantee but I have used this method with success on old radios.

The relays should be fine, they may need the contacts burnished.  You can use a business card to burnish the contacts.  Place it between the contacts with some slight pressure closing them on each side of the card.  Pull the card back and forth to clean the contacts. If they are really bad a burnishing tool will help.  Don't file the contacts some contacts are made with layers of different materials the file will destroy them.  I was an engineer for a relay company many years ago.  Burnishing tools were verboten but all of us had them. flowerred.gif

What about using that antiox stuff in spray cans used on vintage pots etc?



#65 Oliveira

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Posted 25 January 2019 - 04:58 PM

Hi Peter.

 

Take a look at this wire ring bearing maker:

 

https://www.youtube....h?v=Xa1M0WwY2_4

 

https://www.franke-gmbh.com

 

Good luck.


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#66 Oliveira

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Posted 25 January 2019 - 05:17 PM

I had never heard of wire race bearings, but apparently it's the way to go when you need large diameters at a low price that fit in a tight space.

It's no surprise that the craftsmen that built these telescopes have either long retired or passed on, so it would seem that Zeiss is not able to support their classic instruments. I researched and called many companies that work with wire bearings to see if the mount was salvageable. 

Hi,

 

From Wikipedia:

 

Wire race bearing:

 

...

The first wire race bearing was invented in 1934 by Erich Franke, co-founder of Franke & Heydrich KG in Aalen, Germany (nowadays Franke GmbH). As a young design engineer of Carl-Zeiss-Werke in Jena, Franke intended to design a very space-saving bearing for an optical device. The aim of his thoughts was a much closer relation between bearing and enclosing design to keep it as compact and as lightweight as possible.

 

And form technical information:

 

http://www.franke-gm...acebearings.pdf


Edited by Oliveira, 25 January 2019 - 05:20 PM.


#67 Peter Ceravolo

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Posted 25 January 2019 - 07:41 PM

Thanks Oliveira,

I tried contacting a few companies, but non would help for very understandable reasons. This is an old instrument that would be hard for them to deal with, and even if they would help the price would be very high.

Peter



#68 Peter Ceravolo

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Posted 26 January 2019 - 12:14 AM

Here are the accessories that came with my Zeiss. All except the last pictured, the full aperture solar filter, are not very useful in this day and age.

Give Naglers or give me death...

 

All the optical parts are weathered or damaged/incomplete to some degree, and the coatings are probably mag fluoride, not very good. Of course they will be kept for historical reasons, but will be the last priority for refurb, if touched at all.

 

IMG_9250.JPG

 

This is the solar/lunar planetary plate camera that uses a projection system to magnify the image.

 

IMG_9251.JPG

 

This astrograph is interesting, but I was not able to find any details of it's optical design. The coatings are not great, mgf2, there will more than likely be a lot of ghost images if paired with a large format CCD camera. And of course the lenses need to be touched up because of surface degradation.

 

IMG_9253.JPG

 

This full aperture solar filter might be useful, but there are pinholes....

 

IMG_9265.JPG


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#69 Peter Ceravolo

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Posted 26 January 2019 - 12:28 AM

IMG_9259.JPG

 

The 150mm f/15 semi - apo objective was tested with a Ronchi grating and high quality optical flat and whitish light LED.

One can see that the spherical correction is quite good and figure very smooth. The Ronchi lines are not straight, they tend to curve in one direction suggesting some astigmatism. It's probably a little stress caused by the cell.

 

IMG_2325.JPG

 

Here is a 6" f/15 Jeagers achromatic objective for comparison.

 

Jeagers6F15-1.JPG

 

Of course the 40 or so year old objective is weathered. The exterior surfaces, at least, need to be re polished. Although it would be expensive, modern AR coatings would be desirable.

 

IMG_9257.JPG


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#70 Kokatha man

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Posted 26 January 2019 - 02:28 AM

Whilst still in awe about these marvellous old (now) telescopes...& appreciative of their historical significance as well Peter (& Benach!) - I cannot help but be slightly disappointed by the pictures & comments re the objective lenses here...particularly with the Ronchi comparison with a 6" Jaegers! :(

 

Notwithstanding, a wonderful account of your work & the challenges in renovating/restoring an "iconic" piece of equipment! waytogo.gif   



#71 Peter Ceravolo

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Posted 26 January 2019 - 02:58 AM

Whilst still in awe about these marvellous old (now) telescopes...& appreciative of their historical significance as well Peter (& Benach!) - I cannot help but be slightly disappointed by the pictures & comments re the objective lenses here...particularly with the Ronchi comparison with a 6" Jaegers! frown.gif

 

Notwithstanding, a wonderful account of your work & the challenges in renovating/restoring an "iconic" piece of equipment! waytogo.gif   

 

I wouldn't be too hard on the Zeiss objective, it's quite good given it's nature and vintage. In my 40 years in optics, I do not expect perfection from anyone given the typical challenges one encounters fabricating astro telescopes.

 

The small amount of astigmatism is relatively insignificant, the previous owner never saw astigmatism in the images. The semi-apo aspect implies relatively sensitive substrate compared to the cheap as borscht BK7 and F2 type glasses that can withstand thermo-nuclear ware fare... :-)

 

What really sets this telescope apart is the massive and unique mechanics, not the optics. To be honest, I didn't know the Zeiss Coudé existed until I saw the Cloudy Nights Classified ad. I did a web search of the Zeiss instruments and I was hooked. This telescope would be fun to refurb and perfect for my wife's solar imaging desires....:-)


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#72 Diego

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Posted 26 January 2019 - 11:41 AM

Wow this rebuild is just Soo awesome!!! The detail to finish is top notch. Great work Peter!!!

A friend of mine used to manage a small observatory in the middle of the city. The dome was on top of a tall building. He took me one night and upon arrival I was greeted by a 6" Zeiss coude. At the time I didn't know how it worked, but when I saw the fixed eyepiece I instantly fell in love. This model hade 2 handles that rotated to point the telescope. Once the target was found he triggered the tracking. The base was different than this model. It has a large heavy V fork foot.
It is currently abandoned and deteriorating 😞. If I could I'd buy it...but bringing it down the 10 story building is quite the chore. My friend no longer runs the place and lost all connections...to make matters worse the place is about 4 hours away from me. Buying one of these old beasts ain't easy here as they are usually owned by some bureauoctatic governmental department. Maybe I should try to get more info on the place. I feel it is well worth it! Looking forward on how the project advances!

#73 RalphMeisterTigerMan

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Posted 26 January 2019 - 02:53 PM

It is nice to see the bino-viewer in the accessory case. It was not brought out very often, but I distinctly remember viewing the moon through the 6-inch Zeiss and the bino-viewer. Do not remember which eyepieces were being used but...WOW! Some views you never forget, this is one of them.

I also remember just showing up at the GSO on a Sat. Night in early 1985. Myself and two other observers were observing a very short period variable star actually getting brighter in the eyepiece with just a few hours! That was incredible!

I also remember using the eyepiece turret! Pretty cool!

 

RalphMeisterTigerMan



#74 RalphMeisterTigerMan

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Posted 26 January 2019 - 02:57 PM

They may only be .965-inch eyepieces for the bino-viewer. But do not forget, we are talking about Zeiss .965-inch eyepieces! Regardless, the Lunar bino-viewing experience was unforgettable!

 

RalphMeisterTigerMan



#75 RalphMeisterTigerMan

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Posted 26 January 2019 - 03:06 PM

I realize that enhanced aluminum coatings were not available when this telescope was manufactured. Did Zeiss use a type of protected silver or just regular aluminum coatings on the two first surface mirrors? I imagine there would have been the cost of significant light loss in exchange for the convenience of the Coude focus.

But still, the views were amazing even if there was considerable light loss due to 2 reflections as well as a third in the form of any star diagonal assisted viewing.

 

RalphMeisterTigerMan




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