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


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...



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.