Shades of yesteryear. I can remember popping the glass out of Graflex
shutters and dunking them in a tray of naptha (Probably smoking a Lucky
Strike while doing it)
On Nov 29, 2014 11:09 PM, "Chuck Norcutt" <chucknorcutt@xxxxxxxxxxxxxxxx>
wrote:
> Ah, but there is more than one way to skin a cat. I hope that Rick
> discovers that his problem with the (must be) 200/5 is that there is some
> sticky linkage or spring problem or something simple that means no total
> disassembly as you describe.
>
> However, if it is a sticky diaphragm due to broken down and migrating
> helical grease there is often a simpler solution. So that I don't sound
> daft for suggesting it I should say that I have applied this simpler
> solution on several lenses of my own with good success.
>
> On some lenses it is possible to easily remove the rear lens group as a
> complete assembly by simply unscrewing it. On others it may be necessary
> to remove individual elements by unscrewing retaining rings. (note
> carefully the front side of each element for reassembly). If you find that
> you can do this you may also be able to reach and clean the diaphragm of
> oil without any further disassembly.
>
> The repair technique is to carefully flood the diaphragm blades with a
> volatile solvent such as Ronsonol cigarette lighter fluid. Ronsonol (as a
> brand) is recommended since it's pure naptha** and leaves no residue of its
> own. It also has a convenient pour spout which makes it easy to drip the
> fluid onto the diaphragm. Holding the lens at an angle (so as not to drip
> fluid through onto the back of the front lens elements) place a few drops
> at the edge of the diaphragm cage if the diaphragm is stuck open or
> directly onto the blades if the diaphragm is stuck partly or fully closed.
> Rotate the lens around its optical axis to distribute the fluid. Try to
> activate the blades by repeatedly pressing the DoF preview button.
> Probably nothing will happen at first but the fluid will eventually
> evaporate after mixing with and diluting the oil. During evaporation it
> also carries bits of the oil with it. Repeat the fluid application and
> attempt to operate the diaphragm. You may have to do this *many* times
> with waits for evaporation in between. But eventually it will work and the
> diaphragm will start to move. Keep at it until everything works smoothly
> with no drag.
>
> Reassemble the lens and enjoy it. Understand that you have not cleaned
> off any oil from the internal parts of the lens barrel. That means the
> problem will eventually reoccur. But it might take several years for that
> to happen. If it does, rinse and repeat. :-)
>
> **naptha may mean something different in countries other then the US.
>
> Chuck Norcutt
>
>
>
> On 11/29/2014 4:35 PM, Moose wrote:
>
>> On 11/29/2014 9:20 AM, Rick Beckrich wrote:
>>
>>> Help!
>>> All this 180/200 conversation just reminded me that I have an OMZ
>>> 200/4.5
>>> languishing with a non-working diaphragm (stuck wide open).
>>> Any simple cure?
>>>
>>
>> Depends where the problem is. First thing is to take off the mount. The
>> aperture stop down mechanism there has the auto mechanism tab from the
>> camera and manual button activating a spring loaded ring with a long
>> finger that reaches down into the innards to link with the actual
>> aperture mechanism. Various things may go wrong there, sticky ring,
>> activation 'finger' jumped out of linkage with aperture, spring jumped
>> of its anchors, broken pivot post, etc. Most of those may be pretty
>> easily repaired/reset.
>>
>> I have successfully repaired several such problems on both Oly and other
>> brand lenses.
>>
>> OTOH, if the problem is oil on the aperture blades, one must disassemble
>> to the point of taking the aperture mechanism out and thoroughly
>> cleaning it with a solvent to dissolve the grease/oil.
>>
>> I have cleaned out a very few sticky and/or gritty apertures in 50 mm OM
>> lenses. Sometimes, it comes back. As I recall from now ancient posts,
>> the problem is thought to be focusing helical grease that breaks down
>> with age and an oily component that migrates about. The only sure cure
>> is then complete dis-assembly, cleaning of all oil/grease, then
>> re-greasing. Not worth the trouble for any but exotic lenses, I'm afraid.
>>
>> But if one LIKES taking things apart ...
>>
>> Tinkerer Moose
>>
>> --
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