fungus in Cooke lens

[Marko Trebusak]

Well, this one is short: I have a chance to buy Cooke Anastigmat Series II 10inch lens with soft-focus adjustment, but seller informed me, that there is significant (2 cm in diameter) fungus spot on one of lenses. They also told me, that lens was send for repair and repair shpo was unable to clean it. He is offering it for 70 £. Now for the question: If I decide to get it, what can I do? I guess that for 70 quid it's still worth getting it and play with it. Then if I decide that fungus is interfering with my photos too much, what is there to do? Re polishing? And by who? I live in Europe, so some German or British service shop might be the answer. Any suggestions?

Cheers,
Marko

[L&Scape]

Marko,
Some months ago I purchased Geronar lens elements with a lot of fungus. I tried to clean the lens elements with eg. microcloth, alcohol, polypropyl alcohol, purified petrol, destilled water etc. with no succes. Then one of my friend who knows about chemisty suggested me to try with an alkal, like bleach. I reinstalled the lens elements, soaked in mild bleach and the fungus was away immediately! Cheap, unharmful and very suitable for removing lens fungus.

[eddie]

for 70 quid do not worry about it. i am willing to bet it will never show in the photos.....70 for a SF cooke lens....let me at it...:)

[Jim Galli]

for 70 quid do not worry about it. i am willing to bet it will never show in the photos.....70 for a SF cooke lens....let me at it...:)


What Eddie said. You won't see the fungus in the pics and it's a marvelous lens. It should be cleanable. Perhaps the guy was spooked by the extra mechanics of this particular lens.

[Marko Trebusak]

Perhaps the guy was spooked by the extra mechanics of this particular lens.

Thanks for the replies. Knowing you folks and your suggestions from past treads, I went on and ordered the lens :D. Now Jim, what is so special about mechanic of this lens? I mean it's not Portrait series II, but Anastigmat series II. When shovelling through old treads, I found it shall have "unscrewable rear element" for soft focus effect and it shall be very subtle. Can you tell me more about drawing characteristic of this particular lens?

Cheers,
Marko

[Marko Trebusak]

Well, I just can't believe how time is flying. Now I have Cooke in my hand. Fungus is far from being bad and I'm sure it will disappear after some treatment (I too am a chemist). But lens have another problem: front cell looks like wont screw to rear part of the lens. I tried numerous times with no success. Now to the question: since threads on both parts of the lens looks undamaged, is it possible that I have mismatched front cell? Or is there a trick to preform this simple operation? To me mechanic looks straight forward.

Ah yes, another question: can some kind soul tell me the age of this thing? Serial number is 32694.

Cheers,
Marko

[sun of sand]

I had a lens with quite bad fungus
covered probably 60% of the outer element/s and 30% of inner
Fungus was worst outer elements as was inside the balsam
I just dipped the element in bleach water after trying with Noxema/cold creme/nose oil on the outside ..which worked very well itself
Soaked in numerous changes of distilled water afterwards and maybe alcohol to hasten drying

The fungus in the balsam had etched 20% of the glass
Fungus everywhere else came off without a problem. All is fine cept for the etching

Some resolution loss but not all that bad, really. Only till great enlargements are compared to another similar lens is it truly noticed

On large format and with an older, less etched, softer by design lens..

[GPS]

...
The fungus in the balsam had etched 20% of the glass
Fungus everywhere else came off without a problem. All is fine cept for the etching

Some resolution loss but not all that bad, really. Only till great enlargements are compared to another similar lens is it truly noticed

On large format and with an older, less etched, softer by design lens..

Glad somebody said that. You can never say "You won't see the fungus" unless you have seen the extent of the etching the fungus has done - and that is only visible after you removed the fungus itself. Makes sens that the etching was greater in the balsam area where it found better living conditions. I have seen lenses eaten by fungus so badly they could serve as ground glass - were they flat...:)

[Paul Fitzgerald]

" Now to the question: since threads on both parts of the lens looks undamaged, is it possible that I have mismatched front cell? Or is there a trick to preform this simple operation? To me mechanic looks straight forward."

Some Cooke lenses are marked at the starting point. If not:

place the barrel on a table straight up
place the cell on the barrel squared up
rotate the cell counter-clockwise slowly until you hear it 'click' into place
now rotate the cell clockwise to thread it into the barrel

have fun with it

[Jim Noel]

Use Listerine to kill the fungus! Works better than all the other concoctions.

[Robert Hughes]

Listerine is ethyl alcohol, menthol and a few medicine-ey extracts to make it taste special. Strong vodka would probably work just as well.

The 2 problems with fungus are: #1: the fungus excretes acids that literally etch the glass. You can't get rid of the etching, short of regrinding the lens. Even worse, #2: it can spread into the rest of your camera gear. Do you really want to risk ruining your other lenses?

Just walk away. Or use that lens on a homemade box camera, away from your other gear. Or pound it into smithereens at your next camera meet while your LF friends watch in horror - that's always good for a laugh!

[Carsten Wolff]

.....thus spreading fungal spores to settle on everyone's camera gear.....

[Mark Sawyer]

I suspect the fungal spores are pretty prevalent throughout our environment already. Their just waiting for the right growing conditions.

[Marko Trebusak]

Some Cooke lenses are marked at the starting point. If not:

place the barrel on a table straight up
place the cell on the barrel squared up
rotate the cell counter-clockwise slowly until you hear it 'click' into place
now rotate the cell clockwise to thread it into the barrel

have fun with it

Thank you Paul. I already tied that and it would only turn around 10 degrees and got stuck. I can't find enough dirt on the treads for that to be reason for lens got stuck. I'll go all the way and send it to colleague who is industrial optician and know mechanics as well. We'll see what will happen. Image on ground glass looks rather nice.

Anybody have a serial number/age table for TTH?

Cheers,
Marko

[Marko Trebusak]

Thank you folks for your replies. But you know, I've been working with micro-organisms for 10 years plus I'm a chemist by education, and that's why I wrote, that I know how to deal with fungus. I'll appreciate if someone could tell me, what I'm doing wrong trying to put both parts of my Cooke lens together. It would only turn about 10 degrees and then get stuck, although I can't see dirt in threads. I would also be very thankful for TTH's age/serial number table.

Cheers,
Marko

[GPS]

Well, this one is short: I have a chance to buy Cooke Anastigmat Series II 10inch lens with soft-focus adjustment, but seller informed me, that there is significant (2 cm in diameter) fungus spot on one of lenses. They also told me, that lens was send for repair and repair shpo was unable to clean it. He is offering it for 70 £. Now for the question: If I decide to get it, what can I do? ...

Then if I decide that fungus is interfering with my photos too much, what is there to do? Re polishing? ....
Cheers,
Marko


Thank you folks for your replies. But you know, I've been working with micro-organisms for 10 years plus I'm a chemist by education, and that's why I wrote, that I know how to deal with fungus.
...
Cheers,
Marko

Sorry Marko for the good will people had in answering your problem with the fungus.
Your original question didn't show that you've been working with micro-organisms for 10 years plus that you're a chemist by education and that you know how to deal with fungus... Quite the contrary...;)

[Larry Whatley]

Marko, if the fungus Has etched the glass, you may want to re-polish it. That requires a pitch lap, but I have done several without too much difficulty, and they test out just fine on the bench. Let me know if you would like to try doing this yourself. - Larry

[Marko Trebusak]

Marko, if the fungus Has etched the glass, you may want to re-polish it. That requires a pitch lap, but I have done several without too much difficulty, and they test out just fine on the bench. Let me know if you would like to try doing this yourself. - Larry

Hi Larry,

Thank you for the offer. Now that I have lens in my hands, I realised that fungus is the least of it's problems. Damaged threads are the main thing I'll have to sort out. Fungal colonies are not that big and I'm pretty sure that glass is OK. And since we are talking about portrait lens, even in the worse scenario would be a bit less resolution which is not a big deal. But I sure would like to hear your method for do-it-yourself re-polishing.

Cheers,
Marko

[Larry Whatley]

Hi Larry,

Thank you for the offer. Now that I have lens in my hands, I realised that fungus is the least of it's problems. Damaged threads are the main thing I'll have to sort out. Fungal colonies are not that big and I'm pretty sure that glass is OK. And since we are talking about portrait lens, even in the worse scenario would be a bit less resolution which is not a big deal. But I sure would like to hear your method for do-it-yourself re-polishing.

Cheers,
Marko

Marko, I've used the following ad hoc method to re-polish several old lenses up to four inches in diameter. The materials and more detail on the process can be found connected with amateur telescope making.

Stretch saran wrap over the lens surface and tape it in place around the edge (I've wondered if this is really necessary). Then tape cardboard around the edge, making a dam for pouring plaster of paris into the cavity, half an inch deep, onto the saran-protected lens. When the plaster has set, remove the lens and saran, and when the plaster has dried out completely, pour a thin layer (maybe 1/16 inch) of hot pitch (tempered for lap-making) onto the plaster. Let the pitch cool somewhat, remove the cardboard rim, and lubricate the pitch and the lens (no saran) with soapy water (try for no bubbles). Massage the two together once in a while, keeping a good fit as the pitch cools to room temperature. Finally, with a slurry of cerium oxide or red rouge between them, polish the glass with short strokes. Just a few minutes should remove a surface condition (scratches other than "polish marks" are beyond polishing out, I believe).

Some caveats: Do this in a very clean environment (not your workshop) to avoid scratches from a grit particle. Don't wash a cemented lens in running water or in a basin (I separated a group with the thermal shock), and try not to let the lap and glass freeze together for lack of enough soapy water or polish slurry.

Good luck,
- Larry