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View Full Version : Separation or fungus?



Roger Hesketh
25-Apr-2014, 19:14
I am assuming this has to be separation given that it is located within the rear group of a lens of Tessar design. It does however look to my untutored eye rather dendritic. More so than the picture shows. I have thankfully been free from either apart from a little crystalline separation on some Gundlach Turner Reichs I have so do not know what to make of this. I would appreciate your opinions.

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Also I wonder if anyone recognises the focusing mount this lens,the same lens, is mounted in.

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The Dallmeyer catalogue says it will cover quarter plate which is probably rather conservative give it is 6" lens which they also say will cover an angular field of 50 degrees. Every one of these lenses I have seen pictures of is mounted in a focusing mount for motion picture use and this one appears to be too, but different from any of the others I have seen. The lens board is part of the mount. Just curious that's all. Thanks in advance.

Roger

Leigh
25-Apr-2014, 20:33
We need a much clearer, well-focused image in the first case.

- Leigh

Roger Hesketh
26-Apr-2014, 00:28
We need a much clearer, well-focused image in the first case.

- Leigh

You're right I do beg your pardon. It looked sharp enough to my beer fuddled mind late last night but was clearly beyond the close focusing capabilities of the digital compact I was trying to use and my ability as a photographer to capture. In truth even a well focused image does not impart much more information as the lens flaws are clear, very nearly transparent, and when the lens is tilted to make the flaw visible to the camera all the fine detail is lost. In the clear light of day it would appear to me to just be a balsam flaw but an unusual one.

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This picture is not much better. Could a moderator please delete this thread. Sorry for wasting everyone's time.

IanG
26-Apr-2014, 01:59
It's not separation, it looks organic in it's growth, theirs different fungi/mold attacks.

I have a similar size plain sunken mount Dallmeyer 6" f3.5 lens, mines just marked as a Press lens, it's on a Dallmeyer light weight press camera (a re-badged Ensign).

Ian

Steven Tribe
26-Apr-2014, 05:07
The original photo was more than good enough!

Usually described as "fern/coral" growth in the balsam layer! In spite of appearances, it is a crystalline chain reaction. That is, something is being precipitated from the aging balsam which grows in much the same way as a snowflake does. There is no evidence of it having bacteriological or fungii catalyst cause - But it is possible.

There are no evil effects on glass and it disappears along with old balsam.

You are certainly not wasting our time!

hoffner
26-Apr-2014, 05:32
Thanks Steven,
for the good words to the OP. I had the suspicion it was ageing balsam but having not experience enough I didn't vociferate about it. But as much I know that even if the OP took pictures with the lens it would not show up. These defects are surprisingly forgiving.

Leigh
26-Apr-2014, 07:09
As a comparison...
Fungus generally appears as thin tendrils, radiating from the original point of infestation.

There's a current thread about fungus with some photos: http://www.largeformatphotography.info/forum/showthread.php?112742-Coating-problem-fungus-what-is-it&highlight=fungus

- Leigh

Jim Noel
26-Apr-2014, 07:17
Definitely fungus.
The focusing mount is likely off a film pack camera, but I have no idea as to which one.

Fotoguy20d
26-Apr-2014, 07:31
I like Steven's answer personally (not that I know if he's correct or if the correct answer is fungus). I have a Wolly Tele-Optar which has a "snowflake" like that in the front cement pair. I'd always assumed it was fungus but Ive owned the lens for a couple of years and it hasn't grown (despite being locked up in a UV safe box) or changed in that time so maybe not.

Dan

Francisco J. FernŠndez
26-Apr-2014, 08:11
yes, are fungi.

spores are in the air when the lenses were assembled. cement is tight for years (balsam of Canada and other substances) but one day, a slight separation between the layers of lenses.
allows entry from a little water (humidity) and spores grow following several patterns. threads, dendritic, and others. They feed on balsam and mineral layers Multi Coated, or Coated ... when the water runs out, the fungus is stops growing. but the food brand is forever on the surface of the lens.

Why the shape looks growth crystal? because this feeding pattern on glass, and the fungus is eating balm minerals besides other salts.

dendritic shapes commonly grow in the way of animals, plants and minerals.

It is a growth that uses the space available.

Following is a fractal growth patterns . that occurs from molecules to galaxies . at all scales (part of the golden sequence, or Fibonacci sequence. Phy number ... the number of God).


When the lenses are removed , are detached from them, drawing patterns are more continuous . Son of sinusoidal edges ... and usually have very frequently Newton rings , which are sometimes colored .

IanG
26-Apr-2014, 08:21
In my youth I studied micro-biology at University and the pattern of the growth would depend on the exact fungi species and the conditions at the time it occurred. The pattern on Rogers lens is a typical growth pattern.

Ian

Steven Tribe
26-Apr-2014, 08:32
Whatever it is - there will be no damage to the glass! The real problem is growth on coated lenses which releases HF acid, and which is a great etching compound on glass.

hoffner
26-Apr-2014, 10:41
In my youth I studied micro-biology at University and the pattern of the growth would depend on the exact fungi species and the conditions at the time it occurred. The pattern on Rogers lens is a typical growth pattern.

Ian

The fact that the pattern is similar to a growth pattern is no indication in itself of its biological origin. In that Steven is right - crystallising matters also evolve in a similar way.

Francisco J. FernŠndez
26-Apr-2014, 12:15
The fact that the pattern is similar to a growth pattern is no indication in itself of its biological origin. In that Steven is right - crystallising matters also evolve in a similar way.



It is a pattern of growth, according.

a living organism and a crystal system can follow a similar pattern.

Have you looked at with a magnifying glass?

then clearly is not a crystalline body. no it is not.

IanG
26-Apr-2014, 12:49
It is a pattern of growth, according.

a living organism and a crystal system can follow a similar pattern.

Have you looked at with a magnifying glass?

then clearly is not a crystalline body. no it is not.

Totally agree.



The fact that the pattern is similar to a growth pattern is no indication in itself of its biological origin. In that Steven is right - crystallising matters also evolve in a similar way.

In this caseit's clearly not the more typical filament type growth that looks more like the Crystalline issues Steven Tribe alludes to. One of my friends buys and sells a lot of lenses (mostly modern), he lives on a Peninsula (Cornwall) and finds a much high percentage (than you'd expect) of lenses have fungus. He puts it down to the sea air and a high humidity throughout the year.

However I think Roger's lens has actually been stored in far worse conditions (for a while) because this isn't the usual type of fungal attack. It's very definitely organic and I've seen a similar fungal attacks (same shape) on negatives and prints stored in conditions where you occasionally get extreme damp. First was my Grandmothers cellar where she stored he photos - normally very dry but she didn't know there was a stream under a flagstone that occasionally made it extremely damp. The other was a museum I worked for who had their photo archive in their basement but the River would flood it.

When we look at fungal attacks on lenses think laterally, we get athletes foot, we eat mushrooms, blue cheeses. all very different and that's the same with with regards to fungi etc, attacks lens.

Then we are forgetting that in the right conditions balsa can also be attacked by bacteria.

Ian

Roger Hesketh
26-Apr-2014, 23:37
Thank you Steven for your kind words and your assessment. Leigh thanks for the link.I was aware of Ginette's post. This is quite different.Thank you all for your imput. I now feel less like I have asked a stupid question that had an obvious answer as we have clearly had divided opinion amongst people who's opinions I respect and value
In my youth I studied micro-biology at University

So did I. Something else we have in common. After I decided teaching was not for me I worked for a few years as a Biology Technician at our local Grammar School preparing apparatus and materials for practical lessons. Actually being a Technician can be fun as you have a wide range of playthings and resources at your disposal and are encouraged to play with them. We did quite a lot of microbiology. I have poured and prepared thousands of Agar plates and assisted in the interpretation of results of microbiological practical work. The point I am trying to make is I am familiar with many of the fungal growth forms and in this case with this lens I am not sure. The fine detail that is missing from the photographs is that within each dendritic lobe their appears to series of conchoidal concentric fractures. This does look to me like mechanical damage to the balsam.

I strongly suspect you are ALL at least partially correct in your assessments and also that the condition of this lens has been caused by poor storage as Ian suggests. On close inspection their is just a hint of a wisp of hyphae between the two front elements. Of similar type to that which Leigh and Fransisco describe. That in the rear group is very different and I suspect may be caused by a process similar if not identical to the process Steven describes perhaps initiated by fungal action as I have now found a wisp of what looks like it elsewhere in the lens. So clearly it has been stored at some time in conditions that encouraged fungal growth. I have learned something. I was not aware that fungal growth could occur between cemented surfaces.

Jim I am not familiar with the term film pack camera and do not know what you mean. Ian the lens is the same as yours.Just in a different mount. It is a focusing mount not a sunken mount as fitted to press reflex camera. The brass lugs attach to the the focusing ring not to the aperture ring as they would on a sunken mount lens.

It is a recent purchase as I am sure you have suspected. It was an impulse purchase and one I am not sure I know what to do with. I have possibly better 6" Tessar type lenses. I have a 152mm Ektar and a coated 6" Ross Xpres for instance. Possibly it could be used as a portrait lens on roll film. Shallower depth of field than the other lenses mentioned. Lower in contrast, not as sharp as a slower Tessar I am guessing, softer wide open possibly. I do not know. If you have and use such a lens I would like to hear your experiences with it. I paid the princely sum of £2 for it at a car boot sale last week. At that price even though I have more than enough lenses I could not resist it.