Fungus on antique Lens: Can it be fixed?

[Drew Bedo]

I have gotten a nice little antique lens by a well known lens maker. Everything looks great with little corrosion on the finish, focus motion is smooth etc . . .I like it. I would like to put it on my Kodak 2D and shoot a few dry plates.

A careful examination show's fungus between the cemented front elements.

Can I fix this?

[ic-racer]

Fixing lenses is a whole second past time in addition to photography. I get as much enjoyment out of fixing stuff as I do making photographs.

[pendennis]

Fungus can be tricky. If it hasn't etched the glass, you can remove it. There are a number of ways to accomplish this piece of the job. On a lens of age, it may be cemented with Canadian balsam, which is difficult, but not impossible, to obtain. You'll need to align the elements, and it will probably need collimation.

Depending on the degree of etching, the lens may be usable, maybe not. I found a 8.5" Commercial Ektar a few years ago, but the fungus had etched the lens so badly, that only the hardware was salvaged.

[Peter De Smidt]

One option is to nuke the fungus with uv light. Hopefully, that would kill the spores. Take some pictures. You might find that the lens works for your purposes just fine. Otherwise, it's the separate elements, clean them off, hope that the glass isn't etched too badly, re-cement.... method. The latter option sounds like a lot of work. If it sounds like fun work, though, then by all means go ahead.

[Jim Noel]

If you decide to take the lens apart, good old Listerine is as good as it gets to kill the fungus. Not the flavored, but the original awful tasting stuff.

[Andrew Plume]

Hi Drew

Steven Tribe (who is on here) has (from memory) some more than decent experience with this sort of thing and he's posted in the past re this, might take a little time to find his post as he can be a frequent poster on here

Good luck and hope your 'eBay career' continues to prosper.....................

regards

Andrew

[Two23]

Set the lens facing direct sunlight for a couple of days. I once opened the shutter and taped the lens to a south facing window.

Kent in SD

[Drew Bedo]

This is an antique wet-plate era lens by Darlot. I will try to post a few pictures showing the fungus and how the lens is assembled. I can't see how to get the front cell out of the mount.

[Mark Sawyer]

If it's in the cemented surface, it's really hard to differentiate between the various forms of fungus damage and the various forms of cement failure. Even if you repair it, you may never know for sure what it was.

But the solution for either is the same. Separate, clean, and re-cement. Whatever you use to separate and clean will also certainly kill the fungus. But I'd disinfect the barrel too.

[Embdude]

This is an antique wet-plate era lens by Darlot. I will try to post a few pictures showing the fungus and how the lens is assembled. I can't see how to get the front cell out of the mount.

It just keeps unscrewing...

Most likely your Darlot is of Petzval type
205186

If it is indeed between the cemented pair then it is more likely balsam separation than fungus, or at worst separation that has let fungus in. You can boil the elements or use acetone to remove the Canadian Balsam (clear glue from Canadian trees). I have also heard of using a little acetone on a q-tip around the edge of the cemented element and capillary action takes it into the separated section and can fix it by thinning the glue...

205189

Canadian Balsam was used for over a hundred years but today most modern lenses use a different glue type. You can still get Canadian Balsam as well as the new type of glue which cures in UV light. The advantage of the Canadian Balsam is it is easily undone with hot water or acetone the UV glue is not as easily undone.

205190

[Steven Tribe]

Sorry, but there is a good deal of hearsay and misleading (wrong!) information here already!
There are a number of lengthy thread on balsam replacement in the DIY section.

- Don’t use hot/boiling water. Heat transference is far too Quick and will stress the glass. Both cracking and Devitrification.
- Sterilisation is a waste of time. Fungus spores are everywhere - correct storage is the Way to go.
- Sounds like balsam breakdown, which can have tendril-like appearance. Long term zylol bath (up to 2/3 weeks) to separate.
- Many well known makers used turning down thin brass edges in a lathe to Mount glass, rather than screw mounts. A skilled machinist can open these up on a lathe -we can’t, but can do it with hand tools. Result can be a Little rough.
- Canada balsam is the same stuff that is used in microscope slide making.

[Drew Bedo]

It just keeps unscrewing...

Most likely your Darlot is of Petzval type
205186



205190

Thanks. However, this is not a Petzval design. The markings say
Hemispherique Rapod" which I understand to mean that it is of the Repid Rectilinear design. The front and rear cells donot seem to unscrew. I hesitate to jujst start prying on things with a thin knife blade. or on thing,its 250 to 170 years old and about anything is likely to fail from aqge alone. The second reason is that this is from a well known maker. if I was trying to salvage parts from a no-name unmarked partial assembled non-collectable lens I might feel different.

Anybody here know how to properly dismantle this lens?

[pgk]

If you intend to use the lens then try it out before doing anything else. I have been using old lenses with many optical faults including balsam separation, scratches, yellowing of the balsam and so on. Despite this they can produce surprisingly good results. I say can because the biggest problem is an increase in flare so I find it essential to use as much shielding as possible. I have just bought a Hasselblad Pro Shade from a dealer for the vast sum of £15 which I will modify and make front cutouts to match each lens I use it with. Ungainly perhaps but quite a cheap and hopefully effective solution to minimise flare and optimise contrast. Post 3807 here: https://www.largeformatphotography.info/forum/showthread.php?36782-Show-off-your-Large-Format-camera!/page381 is taken on a 1860 lens with such flaws.

[pgk]

And just to illustrate this further, here is a shot taken on an 1859 lens (using a step and repeat digital back I am building on a Gandolfi) and then stitched and processed in Photoshop) which, whilst not perfect, is a reasonable enough image.
205195

[Steven Tribe]

Thanks. However, this is not a Petzval design. The markings say
Hemispherique Rapod" which I understand to mean that it is of the Repid Rectilinear design. The front and rear cells donot seem to unscrew. I hesitate to jujst start prying on things with a thin knife blade. or on thing,its 250 to 170 years old and about anything is likely to fail from aqge alone. The second reason is that this is from a well known maker. if I was trying to salvage parts from a no-name unmarked partial assembled non-collectable lens I might feel different.

Anybody here know how to properly dismantle this lens?

The quoted article matches my experience.
Most RRs/aplanats do have these Quick mountings. They are not designed for servicing. Advances in Optics at the time (1890’s) meant most makers were expecting their products To be replaced within the decade. A knife edge is the only for an amateur without lathe experience.

The Hemispherique is very much a “run-of-mill” aplanat like many others. The name is just a bit fancier!
Darlot was a Company in difficulties when this was made, having made no contribution to photo optics since 1865!

[Drew Bedo]

[QUOTE=Steven Tribe;1558699]The quoted article matches my experience.
Most RRs/aplanats do have these Quick mountings. They are not designed for servicing. Advances in Optics at the time (1890’s) meant most makers were expecting their products To be replaced within the decade. A knife edge is the only for an amateur without lathe experience.

The Hemispherique is very much a “run-of-mill” aplanat like many others. The name is just a bit fancier!
Darlot was a Company in difficulties when this was made, having made no contribution to photo optics since 1865![/QUOTE

Thanks . . .all good to know. If I mess it up the loss will not be much felt in the field of antique lenses.

I still have an interest in attempting to deal with the fungus issue. Separating the elements and recementing later is a different problem to address later. First, the front cell has to come apart.

How can this front lens cell be disassembled?

[BrianShaw]

I’d consider it non-repairable. As Steven Tribe has said several times, there is a possibility of unrolling the brass lens holder, but if the brass has work hardened it will crack and break. I doubt there is a possibility of anealing the brass with the glass in place. Lathe or thin knife... doesn’t matter; same risk. Other approach would be to cut the retaining rim with a graver and remove the lens. A Gem-setting technique used for use in jewelry. But then you’d need to either raise a new edge to re-retain the lens or figure out some other alternative.

It might be better to use-as-is or relegate it to museum-pice status.

[Drew Bedo]

Thanks Everyone.

From the advice in several responses here, remediation looks less and less likely.

I want to do some additional learning though. I have doubts that this is an 1890s era item. I have read somewhere that the marking from 1860 through 1863 were "Darlot Paris" as engraved on this lens. Previously the marking would have been "Jamin Darlot" and before that, just Jamin. It might be worth remembering the "Rapid Rectilinear" is a term rendered in English, while "Hemispherique" is a term rendered in French, by a Frenchman. Later marks were different in details of address and so on I think. I am just learning these things, so any information is appreciated. I am open to being educated or schooled.

Perhaps I will spend some lens money on a reference book someday. Wikipedia does not have much on it.

[BrianShaw]

If it makes you feel any better, Drew, I have an old RR lens (not nearly as nice as yours) that has the aperture control lever (little knurled knob, it once was) snapped off. What’s worse... I remember snapping it off trying to loosen up the aperture. Can’t figure out how to repair and anyone I ask has no good suggestion. It’s useless to me as a lens but still looks great on the shelf.

[Nodda Duma]

Drew,

If the fungus is in the cemented surface then I can repair it if I can get the glass out. Burnished retainers suck..I know why manufacturers did that but that doesn’t make them nicer for it. :) It’s not period-correct, but I’ve turned burnished retainers down to remove the lens, effected the repair, and then rebuilt the burnishing with epoxy. If you want me to take a look send me a pm.


Take pgk’s advice up above first, tho.

-Jason

[Two23]

1. From the advice in several responses here, remediation looks less and less likely.

2. I want to do some additional learning though. I have doubts that this is an 1890s era item. I have read somewhere that the marking from 1860 through 1863 were "Darlot Paris" as engraved on this lens. Previously the marking would have been "Jamin Darlot" and before that, just Jamin. .


1. Try what I said--exposing to direct sunlight for a day or two. If it's fungus that will make a big difference.

2. The Jamin/Darlot period was far earlier than this lens and involved Petzvals. This lens is much later than that. For starters rectilinears weren't much in use until about 1866 and later. This one has later construction so early 1890s is a good guess.


Kent in SD

[Steven Tribe]

Thanks Everyone.

From the advice in several responses here, remediation looks less and less likely.

I want to do some additional learning though. I have doubts that this is an 1890s era item. I have read somewhere that the marking from 1860 through 1863 were "Darlot Paris" as engraved on this lens. Previously the marking would have been "Jamin Darlot" and before that, just Jamin. It might be worth remembering the "Rapid Rectilinear" is a term rendered in English, while "Hemispherique" is a term rendered in French, by a Frenchman. Later marks were different in details of address and so on I think. I am just learning these things, so any information is appreciated. I am open to being educated or schooled.

Perhaps I will spend some lens money on a reference book someday. Wikipedia does not have much on it.

Engraving styles mean Little with Darlot. The same applies to serial Numbers - there are either Numbers/no numbers relating to design or many restarts.

You are misled by the simple extension/locking device which Is the same style as used by the 1865 Universal casket set. American makers also used fancy combinations of names in the late era

[Drew Bedo]

kebt and Steven:

Thanks for your info. I am still learning. A reference book is now on my Christmas wish list.

Stven. . .are you thinking that this could be an American made lens . . .like a Chinese knock-off of a Rolex?

[Tracy Storer]

Set the lens facing direct sunlight for a couple of days. I once opened the shutter and taped the lens to a south facing window.

Kent in SD

Make sure there is nothing flammable in the path of infinity focus (as the sun transits the sky).

[BrianShaw]

Make sure there is nothing flammable in the path of infinity focus (as the sun transits the sky).

This sounds like a posting based on experience!!!!

[LabRat]

This sounds like a posting based on experience!!!!

A magnifying lamp started a fire on my bench at work a few months ago, when early morning bright sunlight hit it and it burned a plastic ventilation tube, which then set fire to a stack of plastic bags nearby... Luckily someone was there then to put out fire, but a real mess from particle remains of fire extinguisher... And not the first time I've seen it happen...

About the lens, the pix with the light passing through does not look too bad to attempt major service... I'd test it first to see how it works as-is...

Steve K

[Darren Kruger]

Make sure there is nothing flammable in the path of infinity focus (as the sun transits the sky).

Even mistakes can become art. See Chris McCaw's Sunburn work. https://www.chrismccaw.com/sunburn

I remember seeing a video of him taking a day shot with one of his home built ULF cameras with smoke coming out everywhere from the camera.

-Darren

[Philippe Grunchec]

http://www.lereveedition.com/fr/dossiers-collectors-11-a-20/n-14-jamin-darlot

Jean-Loup Princelle's books are very useful!

[Drew Bedo]

Drew,

If the fungus is in the cemented surface then I can repair it if I can get the glass out. Burnished retainers suck..I know why manufacturers did that but that doesn’t make them nicer for it. :) It’s not period-correct, but I’ve turned burnished retainers down to remove the lens, effected the repair, and then rebuilt the burnishing with epoxy. If you want me to take a look send me a pm.

Take pgk’s advice up above first, tho.

-Jason

I am thinking I will go the UV light path. Someone off this board thought several hours in the kitchen oven at 150 deg F might help . . .Maybe , but I'll try sunlight first.


Noda: Don't think I'll take your path. I did that once quite a few years ago and it turned out well. I had gotten 10 Wollensak Oscillo Paragons salvaged from Tektronix oscilloscope cameras. Got them for $5 each! There was a heavy aluminum mounting collar threaded onto the lens barrel on each and cemented there in some way. Tried everything I could manage such as strong solvents and heat. Finally took them to a gunsmith. He chucked each lens cell into his lathe and cut the collars off. During the 1990s. I sold off 3/4 of them at camera shows for $50 each. Today i sold the last two on e-Bay for $220 each. I may not have asked enough!

I just don't want to do that with this fine looking antique lens, even if I can't remediate the fungus.

i do not think I will