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Re: [OM] Catch all solution for stuck aperture blades

Subject: Re: [OM] Catch all solution for stuck aperture blades
From: John Hermanson <omtech1@xxxxxxxxxxx>
Date: Tue, 09 Feb 2010 10:00:03 -0500
If there are any glass elements behind the blades, spraying in a cleaner 
may allow oil/cleaner to ooze between sealed groups.  It would then dry 
and leave really bad stains.  Not much fun if you can't get the assembly 
apart. I use "delicate parts cleaner" as a degreaser.
___________________________________
John Hermanson  |   CPS, Inc.
21 South Ln., Huntington NY 11743
631-424-2121  |  www.zuiko.com
Olympus OM Service since 1977
Gallery: www.zuiko.com/album/index.html


Carlos J. Santisteban wrote:
> Hi all,
> 
> From: AS <alizookoman@xxxxxxxxx>
>> I want to take apart a 50mm lens which has stuck blades. Before jumping
> into this I wanted to find out if lighter fluid is
>> the catch all solution to fixing stuck blades.
> 
> It's a common solution, but I've used Methanol for the "several" blades I
> cleaned in the past.
> 
>> I'll be working with a Canon FD 50 lens.
> 
> Is this the later bayonet version or a breechlock mount one? They're
> somewhat weird. I have a Canon service video for it (the later one), let me
> know if you need additional instructions.
> 
> From: "mes9120" <mes9120@xxxxxxx>
>> None of the oil will evaporate with the solvent.
> 
> Yes, I don't think spraying the blades would be enough. The usual procedure
> means taking apart the lens _and_ the diaphragm mechanism, and soaking the
> individual blades in solvent. _Sometimes_ soaking the whole diaprhagm
> mechanism will work, and you may save some time re-mounting the blades!
> 
>> Test any solvent you choose for residue, and do not
>> get natural oil from your fingers (sebum) in the solvent.
> 
> Absolutely.
> 
>> A cotton swab (Q-tip) is handy
>> for absorbing the washings but lens tissue is less likely to leave fibers
> behind.
> 
> It may help, yes.
> 
>> Sometimes there is no oil evident on a sluggish diaphragm because
> lubrication
>> of the pivots has become gummy either by degradation of the lube or
> collection
>> of dirt in the lube.
> 
> Or the linkage may cause problems even with clean blades and pivots.
> Particularly, FD lenses have a complex linkage. I presume you already know
> their irises are inoperative when unmounted on a camera: bayonet parts
> should be moved to the "mounted" position, and then the iris will operate in
> a similar way to the OM lenses -- keeps wide-open unless the lever is moved.
> 
>> I do not oil the pivots of diaphragms I have cleaned.
> 
> Neither did I.
> 
>> Do not apply solvents such as MEK, Acetone, or Alcohol to diaphragm blades.
> 
> This is interesting, since I always used Methanol. Or is this warning for
> Ehtyl Alcohol only? Sorry, I'm very bad at Chemistry.
> 
>> Some blades are made of plastic and polar solvents may warp the blades.
>> Plastic blades were used on some Agfa/Ansco 120 folders and probably
> others.
> 
> Then it doesn't seem to be an issue with (classic) SLR blades...
> 
> Cheers and good luck,
-- 
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