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MANAGED!! : Separating Konica 85mm Rear Doublet...
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PostPosted: Sat Dec 05, 2015 4:27 am    Post subject: MANAGED!! : Separating Konica 85mm Rear Doublet... Reply with quote

Today I received a Konica 85mm 1.8 Lens (The last/latest version). Overall the lens is mint, however there were tiny round spots inside the rear group. The seller had made full disclosure so I knew that there was problem with one of the rear lens elements. I have repaired / cleaned many lenses, so I presumed that this wouldn't not be difficult to clean if it was fungus or haze. However after opening the lens from the rear, I realized that it appears to be vaporized glue or something in between the sealed group. This group has 3 lenses, the rearmost lens was easy to take out with the lens spanner, however the remaining two appear to be sealed together . I have tried heating (first under light bulb and then in oven slowly raising temperature with each try upto 230F) but it didn't help. Now I soaked the group/doublet in acetone, but after a few hours, nothing seems to have changed. I am pretty sure that the lenses are glued with some modern epoxy. Does anyone have any suggestion regarding how could the lenses be removed to clean the elements from inside?

If anyone can help, then it would help me save this lens, else its just going to be a paperweight. Thanks in advance.

(Group in the rear)


Last edited by starlights on Tue Dec 08, 2015 3:39 pm; edited 1 time in total


PostPosted: Sat Dec 05, 2015 7:04 am    Post subject: Re: Request for help : Separating Konica 85mm Rear Doublet.. Reply with quote

starlights wrote:
If anyone can help, then it would help me save this lens, else its just going to be a paperweight. Thanks in advance.

Those two pieces are cemented together. What this cement is actually made of I dont know, but I remember trying to separate cemented elements a long, long time ago and I ended up shattering one of them. This stuff is strong.
But supposing you do succeed in separating the two elements, do keep in mind that they are centered relative to each other at the factory and it is not very likely you will be able to re-center them with the same degree of precision. I think this aspect is likely to affect the image to a far greater degree than the presence of a few spots.
How bad are those spots BTW? Even if they covered 50% of the lens surface, this would only produce light falloff equivalent to one f-stop. In the event, you would be stuck with a slightly darker, but perfectly usable 85mm. Not quite the paperweight you fear. Smile


PostPosted: Sat Dec 05, 2015 12:47 pm    Post subject: Reply with quote

Most probably your dublet is glued with UV cement and not with Canada Balsam - the lens is not old enough to use Canada Balsam.


PostPosted: Sat Dec 05, 2015 2:40 pm    Post subject: Re: Request for help : Separating Konica 85mm Rear Doublet.. Reply with quote

konicamera wrote:
starlights wrote:
If anyone can help, then it would help me save this lens, else its just going to be a paperweight. Thanks in advance.

Those two pieces are cemented together. What this �cement� is actually made of I don�t know, but I remember trying to separate cemented elements a long, long time ago and I ended up shattering one of them. This stuff is strong.
But supposing you do succeed in separating the two elements, do keep in mind that they are centered relative to each other at the factory and it is not very likely you will be able to re-center them with the same degree of precision. I think this aspect is likely to affect the image to a far greater degree than the presence of a few spots.
How bad are those spots BTW? Even if they covered 50% of the lens surface, this would only produce light falloff equivalent to one f-stop. In the event, you would be stuck with a slightly darker, but perfectly usable 85mm. Not quite the paperweight you fear. Smile


I was hoping you would reply - always great to have experienced gurus Smile

The hazing is quite bad - it has rainbows and looks similar to what a lens would look like if someone used vasline coated fingers to handle it, only that its inside of the doublet.

If i fail to separate them successfully then I suppose my only other option would be to find a broken-beyond-repair 85mm and use the doublet from there - but then what are the chances of finding that?

Else, I could reassemble this and use it as soft focus lens - really soft focus lens Very Happy


PostPosted: Sat Dec 05, 2015 2:43 pm    Post subject: Reply with quote

dan_ wrote:
Most probably your dublet is glued with UV cement and not with Canada Balsam - the lens is not old enough to use Canada Balsam.


I think you are right - however I have read that the UV cement can be separated but the newer japanese epoxy cannot.
As a last resort, I will try to boil the doublet in a double pot setup, but I am hoping that someone here can advise me on a better known technique.


PostPosted: Sat Dec 05, 2015 2:48 pm    Post subject: Reply with quote

Oh - and if anyone here has a junk KH 85mm, then I would be willing to buy the doublet off of them...


PostPosted: Sat Dec 05, 2015 3:04 pm    Post subject: Re: Request for help : Separating Konica 85mm Rear Doublet.. Reply with quote

starlights wrote:

I was hoping you would reply - always great to have experienced gurus Smile

The hazing is quite bad - it has rainbows and looks similar to what a lens would look like if someone used vasline coated fingers to handle it, only that its inside of the doublet.

If i fail to separate them successfully then I suppose my only other option would be to find a broken-beyond-repair 85mm and use the doublet from there - but then what are the chances of finding that?

Else, I could reassemble this and use it as soft focus lens - really soft focus lens Very Happy

Thank you for your very kind words. I AM something of a Konica freak, but not much of a guru, Im afraid.
I must say that I am out of my depth when it comes to tackling issues of this sort. The one time when I tried and shattered one of the elements was the last. As a general rule, I prefer not to poke around in lenses unless the problem makes them unusable. At that stage, theres not much to loose anyway.
Unless the lens surfaces are visibly smeared with a film of some type, I suspect the soft focus effect you mention is due to de-centering of the elements relative to one another. If the fingerprint is any indication, the person who put this together was not terribly meticulous and probably didnt make the effort to align things.
Your description, and especially the fact that you couldnt loosen the bond under 230 F degree heat, leads me to suspect that person re-glued the two pieces using some type of transparent epoxy cement. Perhaps the hazing etc. is due to the degradation of a material that was not of very high quality to begin with...?
If you are determined to go ahead, I think soaking the two elements in something for several days may dissolve whatever was used as an adhesive. Did someone mention acetone? If that doesnt work, try cellulose thinner (lacquer thinner in the US). Most epoxies I am familiar with should dissolve after a time.
Do bear in mind that the coatings on the lens elements would probably be gone after such treatment (supposing theres anything left after the oven treatment). But I personally wouldnt worry about this. Spectacular photography existed before coatings came along and a lens without coatings on a couple of elements is still better than no lens at all.
Those are only ideas (of a geek, not a guru Smile ), so only attempt any of this at your own risk.


Last edited by konicamera on Sat Dec 05, 2015 3:19 pm; edited 2 times in total


PostPosted: Sat Dec 05, 2015 3:17 pm    Post subject: Reply with quote

starlights wrote:
dan_ wrote:
Most probably your dublet is glued with UV cement and not with Canada Balsam - the lens is not old enough to use Canada Balsam.


I think you are right - however I have read that the UV cement can be separated but the newer japanese epoxy cannot.
As a last resort, I will try to boil the doublet in a double pot setup, but I am hoping that someone here can advise me on a better known technique.


Boiling works well for Canada balsam - you should be able to separate the element in minutes. If after 10 minutes you don't see top element sliding off, stop, it's not balsam. My understanding is that for UV cement a prolonged soaking in dichloromethane-based solvent is the ticket. But I would also think ahead, because putting these back together may well turn out to be more complicated than pulling them apart.


PostPosted: Sat Dec 05, 2015 3:20 pm    Post subject: Re: Request for help : Separating Konica 85mm Rear Doublet.. Reply with quote

konicamera wrote:
Do bear in mind that the coatings on the lens elements would probably be gone after such treatment .


Lens coatings are produced by chemical vapor deposition and are tough enough to withstand virtually any organic solvent.


PostPosted: Sun Dec 06, 2015 3:40 am    Post subject: Reply with quote

Thanks everyone for responding with suggestions - No luck so far.

I tried boiling the doublet for about 20 mins - no difference, then i put it in a bowl of water and nuked it for about 3 mins (30 sec + 1 min + 1.5 mins) - again no change.

For now its gone back into the jar of acetone until I can figure out something else. The doublet seems to be holding up just fine (too fine actually Smile ) so far..... This is one tough epoxy.


PostPosted: Sun Dec 06, 2015 4:30 am    Post subject: Reply with quote

Zeiss used also glue on Contax SLR lenses, elements are not op-enable Twisted Evil


PostPosted: Sun Dec 06, 2015 6:26 am    Post subject: Reply with quote

Thanks for your encouragement Attila Smile . I wonder if this would work: https://www.optical-cement.com/cements/decementing/decementing.html


PostPosted: Sun Dec 06, 2015 9:21 am    Post subject: Re: Request for help : Separating Konica 85mm Rear Doublet.. Reply with quote

Gardener wrote:
konicamera wrote:
Do bear in mind that the coatings on the lens elements would probably be gone after such treatment .


Lens coatings are produced by chemical vapor deposition and are tough enough to withstand virtually any organic solvent.

That's reassuring to know, considering how prone they are to damage under physical contact.


PostPosted: Sun Dec 06, 2015 9:22 am    Post subject: Reply with quote

starlights wrote:
Thanks for your encouragement Attila Smile . I wonder if this would work: https://www.optical-cement.com/cements/decementing/decementing.html

Too bad they don't specify the ingredients of this potion.


PostPosted: Sun Dec 06, 2015 6:02 pm    Post subject: Reply with quote

Been doing some more research - one article suggested boiling the doublet in oil to effectively raise the temperature to around 350F.
Another response mentioned about freezing the doublet to help break down the epoxy....

Here are some more interesting articles (posting here for reference later) :

http://www.janostech.com/support/cleaning-instructions-for-optics.html
http://jimshomeplanet.com/lensglue.html
http://www.cool.conservation-us.org/byform/mailing-lists/cdl/1992/0112.html


(will add more)


PostPosted: Mon Dec 07, 2015 5:27 pm    Post subject: Reply with quote

konicamera wrote:
starlights wrote:
Thanks for your encouragement Attila Smile . I wonder if this would work: https://www.optical-cement.com/cements/decementing/decementing.html

Too bad they don't specify the ingredients of this potion.


Check MSDS.


PostPosted: Tue Dec 08, 2015 3:26 pm    Post subject: Reply with quote

So here is the GOOD news! Smile - I was successfully able to separate the doublet by putting it in a toaster oven at 450F Bake for 20 mins. lenses appear intact, and have come apart unscathed.
So whatever epoxy Konica used, gives up at 450F. I quickly tried to clean the residual glue (the marks because of which I had to take the doublet apart) and managed to get most of it off with just a bit of hard wiping. I don't want to get too aggressive, so I am letting the two lenses cool. Then I will try to clean the remaining with alcohol swabs. Suggestions welcome.

Before opening the doublet, I had lightly scratched a line across the side in the black paint to match up the lenses - the line is still there, so that's good.

Now, I need help getting some Canada Balsam - anybody willing to send me a small piece? (Washington DC) or atleast tell me where can I buy some from? How do I make liquid epoxy out of it?

Thanks so much everyone!


PostPosted: Tue Dec 08, 2015 3:53 pm    Post subject: Reply with quote

It may be better if you use UV-Curing Optical Adhesives as they are more easy to work with. You can find more information in the link below.

http://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=196


PostPosted: Wed Dec 09, 2015 1:11 am    Post subject: Reply with quote

calvin83 wrote:
It may be better if you use UV-Curing Optical Adhesives as they are more easy to work with. You can find more information in the link below.

http://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=196


Thank you. I have never used any optical epoxy (or Canadian Balsam) before. Any tips or pointers?


PostPosted: Thu Dec 10, 2015 7:06 pm    Post subject: Reply with quote

Surplus Shack has Canadian Balsam -- I think may be worth a try with easily reversible balsam method before epoxy...


PostPosted: Thu Dec 10, 2015 7:45 pm    Post subject: Reply with quote

Please never rename title, it's harm forum search engine position! Congrats!


PostPosted: Fri Dec 11, 2015 2:08 am    Post subject: Reply with quote

visualopsins wrote:
Surplus Shack has Canadian Balsam -- I think may be worth a try with easily reversible balsam method before epoxy...


You make a good point... Thanks. Since I have never done this before, trying out a reversible process would be a better option. UV epoxy is not reversible i suppose?

Apart for the reversible part, does one method have an advantage over the other? Why not go with CB and stay with it... (?)


Last edited by starlights on Fri Dec 11, 2015 2:10 am; edited 1 time in total


PostPosted: Fri Dec 11, 2015 2:08 am    Post subject: Reply with quote

Attila wrote:
Please never rename title, it's harm forum search engine position! Congrats!


I apologize. I was not aware of this issue. Will keep it in mind for future.


PostPosted: Fri Dec 11, 2015 2:25 am    Post subject: Re: Request for help : Separating Konica 85mm Rear Doublet.. Reply with quote

konicamera wrote:


But supposing you do succeed in separating the two elements, do keep in mind that they are centered relative to each other at the factory and it is not very likely you will be able to re-center them with the same degree of precision. I think this aspect is likely to affect the image to a far greater degree than the presence of a few spots.


Before taking the two lenses apart, I had scratched a thin line running across the side of the doublet (on the black paint) The line is still there and helps me to orient the two pieced together as they were before separation. Last night, I applied a little water to the flint and brought it together with the other lens - in the right orientation, they stuck together (with surface tension) and seem to settle into each other like a perfectly fitting glove. Ofcourse this does not guarantee that I will manage to get them together perfectly aligned (optically) to each other, however the fact that they seem to automatically fit together with such precision suggests that it may be doable. We will see when i get to that stage, but i appreciate you making me aware of this issue before running into trouble. Perhaps because of your post, I thought ahead of time to scratch that line on the side of the lens.

Still debating if i should go with CB or UVEpoxy....


PostPosted: Fri Dec 11, 2015 6:38 am    Post subject: Reply with quote

From my little experience UV glue has the chamr to have a lot of time to adjust the lens to your lliking, and then you can have a relative fast curing time. This is the reason why it is so popular today, a machine can hold and adjust the lens assembly, and with a short UV flash it is glued together and can out of this machine. Probably some further UV or heat for full cure.

Canada Balsam without Xylol or such need fast adjustment, cause the lenses and glue get cold.
Canada Balsam with Xylol is slow.. You need probably a lot of patience until you can test it. But I dont like Xylol or those other solvents used for it.
A big pro for Canada Balsam is the easy opening in case something went wrong.

http://www.4photos.de/camera-diy/Delamination-Separation-Repair.html