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Dmh
Tinkerer
Username: Dmh
Post Number: 2
Registered: 04-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, June 03, 2010 - 09:12 pm: | 
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I recently acquired yet another Zuiko 50mm f1.8, the later MiJ version. It's mechanically perfect and cosmetically 99%, but it arrived full of very light filament fungus.
I've successfully cleaned and reassembled the rear elements, and cleaned the front and back surfaces of the front group. But I can't figure out how to separate the front elements, and there is fungus between them.
According to this thread (https://kyp.hauslendale.com/classics/forum/messages/13061/10241.html?1192622842) the group can't be separated, and this manual (http://olympus.dementia.org/Hardware/PDFs/50mm_f1.8.pdf)tends to confirm it.
So this post is a last-ditch effort to find out if anybody has recently advanced the state of the art by devising a way to split the front group. Fungus aside, this lens is too good to go in the spares bin. Any suggestions? |
Der_uli
Tinkerer
Username: Der_uli
Post Number: 9
Registered: 05-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, June 04, 2010 - 03:04 am: |
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I have 1.8/50 Zuikos, never dissassembled them, but had similar problems with a doublet lens from an enlarger. It was glued in place, and had visible separations right in the center.
My solution was to put the complete lens assembly on a piece of thermal insulation, then to heat it up evenly with a heatgun until the cement separated. Its smell was of epoxy.
Heating up and cooling down slowly is important here. Never touch the lenses with cold tools!!
After cleaning I cemented the lenses back together with canada balsam.
If you don't want to go that far it will suffice to pasteurize the front group, that is, to kill the fungus by keeping 90 deg. C for some minutes. It will stay visible but does not grow anymore.
-uli |
Dmh
Tinkerer
Username: Dmh
Post Number: 4
Registered: 04-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 05, 2010 - 05:16 am: |
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Thanks Uli, I'll file that advice away for future use. I don't think this Zuiko assembly is cemented - I've just noticed that the lens cleaning fluid used on the lens yesterday has actually penetrated between the two front-group elements and there are droplets all over the inside surfaces!
Seems bizarre that Olympus made it so difficult to separate the front group but didn't seal it against moisture.
So at this point I have little to lose by experimenting. I've put the assembly in a bowl of warm dilute lens cleaner. When the gap between the elements is fully saturated it will go into a warm convection oven, at about 60 celsius, to dry out. I'll repeat that process in the hope of flushing out the fungus deposits.
Can't help thinking there must be some way to separate the elements and do the job properly... |
Dmh
Tinkerer
Username: Dmh
Post Number: 5
Registered: 04-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 05, 2010 - 05:46 am: |
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Well, the first cycle didn't make any progress. The fungus (or fungus corpse) is still firmly in place, and an irregular tidemark is now also visible. Maybe something other than water is called for - naptha, or methylated spirit...
As well as owning several Cooke Triplets I now also have a Baked Zuiko. |
Dmh
Tinkerer
Username: Dmh
Post Number: 6
Registered: 04-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 05, 2010 - 06:20 am: |
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Does anyone know of a solvent that will take out fungus without risking what's left of the lens coatings? Maybe I could boil the assembly in water, would that dissolve the fungus? |
Gez
Tinkerer
Username: Gez
Post Number: 201
Registered: 09-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 05, 2010 - 07:52 am: |
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I'm guessing this is the Mk4 version of the Zuiko 50mm/1.8, the one with the filter ring integral with the front optical cell, and the whole unit secured to the barrel with 3 screws??
It will be a lot easier just to swap a good front cell off an otherwise damaged lens, there are lots of oiled up standard Zuikos available on the net. |
Dmh
Tinkerer
Username: Dmh
Post Number: 7
Registered: 04-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 05, 2010 - 05:04 pm: |
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Gez, it would be a Mark 4 or 5 depending on how you define it - serial is 38026xx, and AFAIK it's the last version.
I do have one or two other MiJ 50s. If these mad-scientist experiments don't succeed, I'll mix and match the parts with the other lenses. |
Gyurmi
Tinkerer
Username: Gyurmi
Post Number: 14
Registered: 12-2009
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 12, 2010 - 08:23 am: |
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Have you tried mould killer? I think ammonia is the active ingredient that kills growth. I must say, most of my attempts to remove fungus from lenses did not produce the desired results. Yes, the fungus itself is removed or killed, but it still leaves its mark in the coating or even the glass (?). So, it might be a futile exercise. (But, I do know how it feels when you just don't want to admit defeat.) I have the same Olympus lens with the same problem, and could not figure out how to take it apart. Eventually I gave up and bought the other version, which disassembles nicely. |
Dmh
Tinkerer
Username: Dmh
Post Number: 12
Registered: 04-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, June 13, 2010 - 05:00 am: |
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Thanks Gyurmi, I hadn't thought of ammonia. So far I've tried dilute lens cleaner, detergent (the non-residue type not the cheap stuff) and naptha.
Obviously I'm staying with liquids that can be flushed or evaporated out of the lens - I assume that the entry and exit is through pinholes in the glass mounting cement, if it has any.
Given the heat and chemical assault I've inflicted the mould is probably dead by now. The challenge lies in dissolving the mould and flushing it out along with the solvent. The ammonia sounds ideal for the purpose.
Incidentally, this lens assembly gives fascinating effects if reversed and attached to the front of another lens. It's like a lensbaby, but more so. So there's the backup plan! |
Dmh
Tinkerer
Username: Dmh
Post Number: 13
Registered: 04-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, June 17, 2010 - 05:27 pm: |
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The assembly is now soaking in a nice hot bath of dilute ammonia-based window cleaner. Undilute window cleaner was too thick to penetrate the tiny gaps between the components, so I diluted it and now the assembly is filling nicely.
Yes Gyurmi - after all that this lens has been through, I doubt that it will ever be much use for anything serious, but it's a grudge match now and I am not going to be defeated by a colony of fungus. |
Der_uli
Tinkerer
Username: Der_uli
Post Number: 10
Registered: 05-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, June 18, 2010 - 03:20 am: |
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There are sorts of mould killer available which are quite effective against black spots on the wall. Ask your local drugstore. Chemically they are mainly a 5% solution of natrium hypochloride with some detergent = chloride bleaching agent. They decompose into salt and chloride water and need very good flushing after application. I never tried them on lenses, but maybe it helps...
Good luck
-uli |
Dmh
Tinkerer
Username: Dmh
Post Number: 14
Registered: 04-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, June 25, 2010 - 07:50 pm: |
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Thanks Uli. The mould killer would be interesting but the flushing process might be difficult in this instance. Any trace of salt left in the lens would present a problem.
The lens has had the window cleaner in it for a week now and it's in the convection oven drying out. When it's dry I'll post a picture of it. |
Glenn
Tinkerer
Username: Glenn
Post Number: 792
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 26, 2010 - 01:34 pm: |
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15% - 20% sodium hypochlorite will effectively 'kill' the fungus. The problem is then removing the dead residue from the glass - giving the complete lens cell a swim in the equivalent of the local swimming baths is not going to solve the problem. In fact you will probably make the matter worse optically if you are rinsing/flushing the assembly with ordinary tap water - as the water evaporates the dissolved salts in the water will be deposited on the surface of the glass. The use of distilled water will reduce the likelihood of the optic becoming opaque.
If anybody out there is compiling a list of a hundred ways to wreck a lens, this attempt sure belongs in the top 20! I doubt if using a hammer and chisel to separate the front group would have rendered the optic so totally useless as your sessions of hydrotherapy will have done. Still if the object is to produce a lens with the optical properties of a dirty milk bottle, congratulations you have succeeded - I'll forward my Leitz Noctilux for modification in due course. |
Dmh
Tinkerer
Username: Dmh
Post Number: 15
Registered: 04-2010
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, June 27, 2010 - 03:16 am: |
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Yes Glenn, thanks for those encouraging and memorable sentiments ;)
You're right, as I noted several posts ago there is a tendency for "tidemarks" to form. The local tapwater is clean enough for use in a car battery but certainly not for this.
Keep in mind the fact that the lens was effectively unusable, by any reasonable standard at least, when I started. At this point the exercise is largely academic and slightly humorous (I have no intention of getting upset about this lens!)
The rest of this lens - for example, the focus grip, aperture ring, mount and internal mechanical parts - is in excellent condition. The worst that can happen is that it ends up as spare parts for one or more of my other Zuiko 50s - after fumigation of course. |
