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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