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12-01-2008, 04:11 PM   #16
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QuoteOriginally posted by pentaxman Quote
I have used MEK (methy ethyl ketone) to clean fungus from lenses. It works really well. You can get it from painting supply stores (it is used as paint remover, so be careful what you get it on.)

MEK is some very nasty stuff, it is used as a solvent to melt the surface of plastic / pvc pipe fittings prior to gluing. So it melts a lot of plastics, and will certainly remove paint.
It's also very toxic when inhaled.

12-01-2008, 04:33 PM   #17
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QuoteOriginally posted by richard64 Quote
To disassemble the front group I had to unscrew a ring. This one had indents in it. If you see a ring like this, you should use a lens spanner wrench to unscrew it. That is the safest way. Unfortunately spanner wrenches are $20 or $30 so you are now talking about a specialist investment. You can use a screw driver in the indent, but since you will have to use some force, you do risk the screw driver slipping and scratching something.
The problem with using a screwdriver is that you can only apply force to one side of the ring at a time. As far as jury-rig solutions go I've had good luck using a pair of scissors to apply force to the indents on both sides of the ring at the same time - this makes it a lot easier to turn the ring. Of course you have to find a pair of scissors that have points which fit the indents and be very careful not to let them slip and scratch the lens!

Use at your own risk!
12-01-2008, 06:16 PM   #18
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Here is where you get the tools. Particularly important are correct screwdrivers and spanners (those cross-point screws are not Phillips...):
Micro-Tools
Be sure to have a good strong light source and a padded work surface. Some sort of magnifier is also helpful.

Steve
12-01-2008, 06:22 PM   #19
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Dismantling is always the easiest part...

12-01-2008, 06:30 PM   #20
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I have an experienced lens repair friend who tells me he sees so many lenses that have been opened up and assembled by people without the right equipment. If you come across a lens that can't focus correctly at infinity, you can be sure the lens hasn't been collimated to ensure perfect focus at infinity.
12-01-2008, 07:00 PM   #21
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Ha. My effort with an A Series lens was an unmitigated disaster... Those puppies were not made as to be successfully taken apart.
12-01-2008, 09:48 PM   #22
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Ok I'm sufficiently spooked

I took some pictures of a white sheet today and I cannot see any dust or the fungus, which is on the outer edge of the lens. I also cannot see anything through the viewfinder against a bright white background.

I'm going to leave it for a while and if the fungus grows, will attempt the dismantling then.

Thanks for the info though. It will be invaluable when the time comes to give it a go.

Sorry if I got anyone's hopes up of witnessing a disaster
12-01-2008, 11:27 PM   #23
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QuoteOriginally posted by Lloydy Quote
MEK is some very nasty stuff, it is used as a solvent to melt the surface of plastic / pvc pipe fittings prior to gluing. So it melts a lot of plastics, and will certainly remove paint.
It's also very toxic when inhaled.
MEK is actually very similar to acetone. Acetone will also remove paint. This is why it is good at removing fungus - fungus is an organic substance, MEK is an organic solvent. Likes dissolve likes.

I am careful to just dampen the corner of a lens cleaning cloth and then very lightly rub the fungus deposit. It comes off relatively easily. MEK also evaporates rapidly, leaving no residue.

12-02-2008, 02:36 AM   #24
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In order to prevent fungus growth you need to take the moisture away
Store your lens in a ziplock bag with silica gel or some other dissicant to keep the moisture away.



QuoteOriginally posted by ViS Quote
Ok I'm sufficiently spooked

I took some pictures of a white sheet today and I cannot see any dust or the fungus, which is on the outer edge of the lens. I also cannot see anything through the viewfinder against a bright white background.

I'm going to leave it for a while and if the fungus grows, will attempt the dismantling then.

Thanks for the info though. It will be invaluable when the time comes to give it a go.

Sorry if I got anyone's hopes up of witnessing a disaster
12-02-2008, 06:26 AM   #25
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QuoteOriginally posted by Sean Nelson Quote
The problem with using a screwdriver is that you can only apply force to one side of the ring at a time. As far as jury-rig solutions go I've had good luck using a pair of scissors to apply force to the indents on both sides of the ring at the same time - this makes it a lot easier to turn the ring. Of course you have to find a pair of scissors that have points which fit the indents and be very careful not to let them slip and scratch the lens!
Yeah, if you scratch a lens it kind of reverses exactly what you are trying to do!

I have recently bought a pair of dividers - they cost me, say US $5. I intend to file down the tips to the right shape and use those.

Richard
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