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Unitron 140, fungus question

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7 replies to this topic

#1 39cross

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Posted 22 June 2020 - 09:48 AM

Hi Classicists,

 

A local opportunity has come up to purchase what looks like a complete Unitron 140 (OTA, alt-az mount, 5 eyepieces, travel box, porro prism etc.).  There is a spot of fungus about the size of a dime on the outside edge of the lens.  I imagine it doesn't really affect the view.  But nonetheless there it is, staring you in the face.

 

So I'm wondering what do you think, is this something that might be able to be cleaned up?  And what would be a fair price, given that the rest of the kit is in good shape?

 

Once upon a time I would have dearly wished for such a scope, but my Sears 6339a is pretty sweet (albeit not the mount).

 

Thanks,

RIck



#2 starman876

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Posted 22 June 2020 - 10:27 AM

Mots fungus issues are cleaned up rather easily.  There have been a lot of threads on this issue.  The only time fungus is really an issue when it has etched the glass.  You will see posts about fogged up lenses, but I have found this to be a non issue as it cleans up rather easily.   Depending on the cost of this Unitron the fungus can be a negotiation point for the price of the scope.   These Unitron lenses screw out of the cell and a couple of screws later the lenses are in your hand and the cleaning process has begun.  Cotton balls and various cleaning supplies approved for lenses and soon you will have a lens that looks like new. 

 

https://www.cloudyni...-fungal-growth/

 

here are some pics of a lens I cleaned.  You can see the lens looked very bad.  An hour later is the same lens I cleaned up.  

 

https://www.cloudyni...man876s-photos/


Edited by starman876, 22 June 2020 - 10:33 AM.

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#3 Bomber Bob

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Posted 22 June 2020 - 10:49 AM

Here's the lens from a 1956 Unitron 152 (4" F15 EQ) that I partially restored:

 

Unitron 152 - Delivery S12 (NASTY Lens).jpg

 

Fungus & filth -- scope sat in a barn for years!

 

Here's the lens after a careful cleaning:

 

U152 Restore S005 - Lens Cleaned.jpg

 

Sometimes they look way worse than they actually are.


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#4 markb

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Posted 22 June 2020 - 10:49 AM

+1 on the ease of a fairly effective cleaning of an objective that can be disassembled.

 

I hope the objective is a good one. I put money on it the Sears is so sweet because it's a royal Astro lens, identifiable by the tiny mark on the name plate. Mine was an essentially perfect objective, I would have loved to have seen interferogram on it. Too long, skinny, and narrow for my taste, it went to an excellent home.

 

With air-spaced elements, just be very very careful with the spacers as you will need to reuse them of course. a recent thread mentioned the possibility of replacing them with gradated machinists plastic shims.

 

I haven't hit etched-glass yet but I have had some damaged coatings, a bit unsightly but no noticeable effect on images.

 

Do the search on cleaning, there are lots of opinions.

I use an old photo forum trick, pond's cold cream, to remove the infection, soap and water, and if necessary acetone if the infection is tenacious. One photo lens did require that. By the large pec pads off Amazon, they won't hurt anything and they're tough to beat for that final swipe to remove lint or dust. I use lint-free microfiber towels made for car washing, from Walmart, the large gray ones, or regular lens cleaning or finishing up with breath fog when cleaning an objective. The Harbor Freight ones leave a lot of lint. I see complaints about their use, but anybody with half a brain would only use fresh towels, not old contaminated ones. They're cheap enough to cut up into squares and use up over a couple of years, but I find the big ones nice for clean objective handling. with a quality lens, I don't care how many I use and decide to throw away, or transition to car use. They have the miraculous ability to wick off oils without rubbing or any solvent other than breath fog. Mostly for eyepieces, or for when you accidentally touch the lens on reassembly . . .

 

Nothing beats pecpads for a safe resting place as you're working though, the only problem is they are nonabsorbent.

 

I've never used the cotton pads, but they are classic for safe mirror handling and cleaning.

 

And don't over tighten the cell retainer when you restore the lenses to their home.

 

Mark the relative positions and the, believe it or not, relative directionality of the lenses. It is just too easy to flip an element, I bought two used scopes that had happened to.

 

On that Sears, try putting the mount onto a stable tripod, or use replacement solid legs. I was in the process of making an adapter for mine when I sold it, legs made it completely unusable even though the amount itself seemed decent.


Edited by markb, 22 June 2020 - 01:41 PM.


#5 39cross

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Posted 22 June 2020 - 01:49 PM

Thanks everyone for the helpful advice and links.  You're the best!

 

-Rick



#6 RichA

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Posted 24 June 2020 - 06:30 PM

Hi Classicists,

 

A local opportunity has come up to purchase what looks like a complete Unitron 140 (OTA, alt-az mount, 5 eyepieces, travel box, porro prism etc.).  There is a spot of fungus about the size of a dime on the outside edge of the lens.  I imagine it doesn't really affect the view.  But nonetheless there it is, staring you in the face.

 

So I'm wondering what do you think, is this something that might be able to be cleaned up?  And what would be a fair price, given that the rest of the kit is in good shape?

 

Once upon a time I would have dearly wished for such a scope, but my Sears 6339a is pretty sweet (albeit not the mount).

 

Thanks,

RIck

Which glass does fungus prefer to digest, crown or flint?



#7 Jim Curry

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Posted 24 June 2020 - 07:20 PM

That's about the fungiest lens set I've ever seen.  You did a great job bringing that back to life.

 

Jim



#8 starman876

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Posted 24 June 2020 - 08:06 PM

That's about the fungiest lens set I've ever seen.  You did a great job bringing that back to life.

 

Jim

Thanks Jim.  When I first saw it I thought will this ever come clean.  Well, as you can see it did.  Most people are scared to take their lenses apart tp clean them.  It really is not that hard.  You just have to be brave.




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