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Final call for lens doublet separation.

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It doesn't sound like everything in the tutorial I wrote will apply to you in this case, however some of it may be of interest: Dead Link Removed (look under Ultimele Tutoriale tab)
If you or anyone here needs some Canada balsam, please let me know. You can dissolve it with several different types of solvents. You can also use a clear/high grade rosin if you need to...it will have about the same optical properties, actually.
Jon
 
Good news. The Hasselblad 80mm front doublet came apart today in the jar of Methylene Chloride it's been in since 7-26-13. I'm going to be using some liquid Canadian balsam in a little bottle I bought from Canada on ebay.Hope it's the right stuff. I didn't like the idea of dissolving the hard sticks in my dusty house. I would have never been able to keep specks out of it as it dissolved.
 
Tom1956 said:
Good news. The Hasselblad 80mm front doublet came apart today in the jar of Methylene Chloride it's been in since 7-26-13. I'm going to be using some liquid Canadian balsam in a little bottle I bought from Canada on ebay.Hope it's the right stuff. I didn't like the idea of dissolving the hard sticks in my dusty house. I would have never been able to keep specks out of it as it dissolved.
Click to expand...

I got mine from the tree.:smile:

Price was right, too.:laugh:
 
Just to chronicle progress for future searchers, Now I have the 2 separated elements on the work table. I'm finding it strange that while acetone was ineffective at separating them and that methylene chloride (DCM) was what did the job, just the opposite on cleaning the residue. Soaking pieces of cotton with DCM, did practically nothing at scrubbing the glue residue off the face of the glass. Acetone seems much more effective at that. I have both elements clean now. I will go over then again, then do the standard Q-tip and cotton swab lens cleaning, and proceed with the balsam gum. So far, so good--no damage done.
 
Now what I'm wondering for a month from now, when it comes to black re-edging of the doublet, is if acrylic base black should be used, to avoid possible bleeding from an oil base paint re-dissoving the sap at that time and leaching into the sandwich. I might note that there is quite a bit of edge surface area, as the edge of the back element is ground at quite an inward angle. I certainly don't like the idea of a black sharpie pen. Not exactly a hard substance in thicker coats.
 
Tom1956 said:
Now what I'm wondering for a month from now, when it comes to black re-edging of the doublet, is if acrylic base black should be used, to avoid possible bleeding from an oil base paint re-dissoving the sap at that time and leaching into the sandwich. I might note that there is quite a bit of edge surface area, as the edge of the back element is ground at quite an inward angle. I certainly don't like the idea of a black sharpie pen. Not exactly a hard substance in thicker coats.
Click to expand...

Black lacquer. I've used RustOleum flat black with success, over 20 years ago and everything is just fine. If the edges aren't exposed to light within the lens, it doesn't matter if the paint is flat, semi flat, or gloss. If the cemented pair mounts in a metal cell, there will not be room for any but the very thinnest coat of blacking. It doesn't matter how durable whatever you use is, as it will not see any wear except for reassembly. Quite a few old lenses wre just smoked black.

Edit - I forgot to mention that you can make a black lacquer with shellac and lampblack.
 
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I never had a problem with a Sharpie pen. As Mr. von Hoegh correctly notes, thickness is important. You don't want it to be too thick or you'll just scrape it off as you re-install the element. Good luck.
Jon
 
It's strange that this thread popped up today after these weeks, because I was going to pull it up for a final update for the archives. My job turned out beautiful. As good as I could ever hoped for. As far as edge blackening I just used a magic marker. But as for the overall job, my first one, on a Hasselblad lens no less--the job turned out beautifully. Thanks everybody.
 
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I have kept my eye on this thread for weeks and what can I say - good job! It takes some serious cohones to take on a task like this and you succeeded!
 
Thanks guys--EvH, JG, and the rest. To put the matter to bed with the intent to inspire others to jump on some repair job you're afraid of, put it in atother perspective. On this one, what did I have to lose? A 250 or 350 dollar lens if I fouled it up? Think about something else. Like a Cancer Center of America commercial. In that light, a botched-up lens job still has me being a lot better off than THOSE people. So get out your tools and your guts, use some sense, refuse to be beaten, and it'll work out. There's no excuse for knucklehead-boob work.
 
Knuckleheads have boobs?
 
Thanks, Jon. You can always be counted on for a serious explanation.:smile:
 
When I was a kid I got caught looking at at my dad's Playboy magazines. I got a knuckle to the head for looking at boobs.
 
"I'm learning in school about plants."
"Botany?"
"No, I don't have any money."
 
:laugh::laugh::laugh:

Of course, now we know what they expire on...
 
E. von Hoegh said:
Whatever solvent is used, patience is the key. It might take anything from a week to a month or more.
Click to expand...

So figure the maximum time it could take-- then doublet.
 
VPooler said:
I have kept my eye on this thread for weeks and what can I say - good job! It takes some serious cohones to take on a task like this and you succeeded!
Click to expand...

Bah. It's just a lens; it was originally assembled by normal human beings, so it stands to reason that one can repair it competently.
Now, if he'd been working on a truly special lens - like a Goerz Dagor - it really would take cojones (note sp.) And talent, and incredible skill, and superhuman and -natural powers, because these lenses are special. The person who designed them is special, the men who made them were special, and the photographers who use them are special, because they use them. And of course the photographs made with them are most special of all.:smile: Even the subjects which are photographed become special.:laugh:
 
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Sorry, English is not my first language :tongue: But you are right, designed and built by humans, although in a specialized shop.
 
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