Kodak 12" fungus - please advise

[prince fritz first]

I am new to this forum so a warm hello to everyone.

I own a Kodak 14" CE which I use for close up portraits on my 4x5. Recently I acquired a Kodak Ektar 12" f4.5 to have a brighter lens to make it easier on focusing in certain situations... Happy thoughts and all!
Well, I received the package today only to find out that the inside of the rear element has fungus spots in it. They are faint and almost invisible when looking through the lens except at certain angles but once the rear element is removed it's much easier to spot - please see attached pictures. I have a feeling that this shouldn't affect the quality very much but I would like to ask out there for an opinion.

Firstly - can this be cleaned at all? I'm certain this is on the inside of of the glass of the rear element. I'm guessing these can't be taken apart?
Secondly - if this can be a workable lens what should it be selling for? If I decide to keep it I need to figure something out with the seller who didn't point this out in the ad.

Please advise - I'll greatly appreciate any and all of your input!

Thank you very much and have a lovely thanksgiving!
Regards,
david

P.S. Here are a few images of the rear element only. The front is perfectly clean.

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[Dan Fromm]

Fritzi, if the spots are on the surface isopropyl alcohol and a microfiber cloth will remove them. Y'r lens is a tessar type so the rear group is a cemented doublet. If the spots are in the cement, you might be able to separate the elements, clean up the mess, and recement them. I've never done this so can't make good suggestions about how to do it.

The lens looks pretty dreadful. If it were mine and I had the right of return I'd send it back for a refund.

[pjd]

If the spots are a fault in the cement between elements it's trouble, perhaps not economic to remedy.

If it's fungus on an outer surface you might well get lucky and find it cleans off easily. Or not! Fungus seems to cause more problems with coated lenses. I've bought uncoated lenses with lots of fungus that vanished completely with cleaning, but also have a dog of a lens (coated) that just had a bit of fungus that left odd blotches in the coating - which surprisingly rendered the lens completely useless, and I'm forgiving of junky looking glass.

About value, I believe valuation requests are not allowed at this forum. You could have a look on igorcamera.com, they might have something similar to give you an idea, or just completed sales on eBay.

[Ted R]

The practical consideration of effect on image quality is in my opinion not great, and for many types of portraits probably insignificant. The spots seem terrible when we focus on them with our vision, however they are out of focus so far as the image is concerned, very out of focus (this can be demonstrated by deliberately attaching to one of the glass surfaces a black spot). The effect of spots haze and fungus is a slight loss of brightness and slight reduction in contrast, neither of these is disastrous in a portrait lens.

Regarding value it depends how you look at things. Can you find the same lens in better condition? For what price?

[EdSawyer]

I don't see any fungus there, but that overall haze looks like degradation of the cement between those elements. It is not easily removed, if so. If it were me I would see about returning the lens and get a better one, they are not that rare.

[Bob Salomon]

Here is what Carl Zeiss states about fungus:

"Fungus means an Infestation of optical instruments with fungus spores which germinate and produce more spores.
Lens surfaces are irreparably damaged by metabolic products of the fungus (e.g. acids). Its damage ranges from cloudiness to opacity caused by the film. The Carl Zeiss T* coating has no significant influence on fungus growth or generation of spores."

Or, in other words, the by products of fungus growth will eat into and etch the glass. So true fungus cleaning is really not possible, without re grinding the lens blank or replacing it. Rodenstock and other lens manufacturers will also tell you this.

[RSalles]

If you have the opportunity, return the lens to the seller. There are much better copies from time to time surfacing the devil bay site, or similar for trade here in much better shape.
This amount of haze and fungus tends to grow up in the future. It's advisable to store this lens in a separate box to avoid contamination to other lenses.

Cheers,

Renato

[RSalles]

Fritzi, if the spots are on the surface isopropyl alcohol and a microfiber cloth will remove them. Y'r lens is a tessar type so the rear group is a cemented doublet. If the spots are in the cement, you might be able to separate the elements, clean up the mess, and recement them. I've never done this so can't make good suggestions about how to do it.

The lens looks pretty dreadful. If it were mine and I had the right of return I'd send it back for a refund.

Dan,

Not intending to brake the rules for mutual friendly living toward the original thread poster, but, have you ever came across to a thorium coated lens contaminated with fungus? I never did, and was thinking about the anti-fungus properties of this type of coating, as a side effect, of course,

Cheers,

Renato

[Dan Fromm]

Renato, I don't think I've ever seen a lens with thorium coating. Magnesium fluoride is what's normally used. Might you be thinking of glass that contains thorium?

I have a couple of lenses that contain thorium glass, all TTH apo tessar types, and have had a radioactive Repro-Claron that did too. No fungus on any of them, like all of my other lenses.

Cheers,

Dan

[prince fritz first]

On the night of being thankful I thank you all very much for all the input and advice!!! I paid $500 for this lens and while it looks really nice this one detail bothered me a bit. I greatly appreciate it!

[RSalles]

Renato, I don't think I've ever seen a lens with thorium coating. Magnesium fluoride is what's normally used. Might you be thinking of glass that contains thorium?

I have a couple of lenses that contain thorium glass, all TTH apo tessar types, and have had a radioactive Repro-Claron that did too. No fungus on any of them, like all of my other lenses.

Cheers,

Dan
Yes, I meant to the glass, not to the coating, sorry for the confusion.
But do you remember have seen a glass with thorium infested by fungus? For sale, anywhere, or in other places but not in your possession?
That's the question, I don't recall to have crossed any. I remember to have found some Takumars and Aero-Ektars with thorium in the glass optics, others with few amount of scratches, but none with fungus. I was tinkering if the radioactive element present in the glass could avoid by any extent the infestation of fungus...
Found two interesting links related:
Camerapedia: http://camerapedia.wikia.com/wiki/Radioactive_lenses
http://www.orau.org/ptp/collection/consumer%20products/cameralens.htm


Cheers,

Renato

[Steven Tribe]

Well, Thorium tetrafluoride has actually been used as an optical coating!

[Ari]

If it's simple fungus on the surface, I've had good success using Hydrogen Peroxide to get rid of it.

[cowanw]

Have you unscrewed the lens, as much as you are able to, to access both sides of the element groups?