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[OM] Re: 24/2.8 stop-down fix?

Subject: [OM] Re: 24/2.8 stop-down fix?
From: John Hermanson <omtech1@xxxxxxxxxxx>
Date: Thu, 01 Mar 2007 09:01:02 -0500
It is not common for this lens to get oily blades. I thinks it's purely 
mechanical.

___________________________________
John Hermanson
Camtech Photo Services, Inc.
21 South Lane, Huntington NY 11743
631-424-2121 | Olympus OM Service since 1977
http://www.zuiko.com  |  omtech1 AT verizon dot net


Tom Fenwick wrote:
> It does sound like it could be that then.  Do they generally become
> completely stuck with no warning, or would you expect to observe a
> progressive decline?
> 
> Tom
> 
> On 28/02/07, Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx> wrote:
> 
>>The fact that it moves freely and feels right doesn't matter.  On an OM
>>mount lens there is no physical link between aperture lever and
>>diaphragm except for pushing the aperture back open.  On stop down the
>>lever just gets out of the way to allow the blades to close and a very
>>weak little spring pulls the blades closed.
>>
>>When you activate the stop down lever you're still feeling normal spring
>>tension for the stop down lever itself... whether the diaphragm follows
>>along behind or not.
>>
>>The simplest analogy I can draw is of a pinball machine with it spring
>>loaded ball release and the ball.  In the analogy the spring loaded ball
>>release is the stop down lever inside the lens.  The ball is the
>>diaphragm and gravity in combination with the slope of the table is the
>>lightweight diaphragm spring.  When you pull back the ball release you
>>expect the ball to follow along behind due to gravity.  If it doesn't
>>maybe there's some sticky substance under the ball preventing free
>>movement.  That's oil on the blades.
>>
>>Chuck Norcutt
>>
>>
>>Tom Fenwick wrote:
>>
>>>I don't think that's what it is - everything moves freely, the spring
>>>tension feels right etc, but the iris just doesn't stop down!  It was
>>>working fine last time I tried it, about a month ago...
>>>
>>>Tom
>>>
>>>On 28/02/07, Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx> wrote:
>>>
>>>>What's the probability that this thing has oil on the blades and is
>>>>stuck wide open?
>>>>
>>>>Chuck Norcutt
>>>>
>>>>Tom Fenwick wrote:
>>>>
>>>>>Hi,
>>>>>
>>>>>I've got a 24/2.8 which has stopped stopping down.
>>>>>
>>>>>I've removed the easy part of the back of the mount, and everything in
>>>>>that section is working ok; ie the lever on the main part of the lens
>>>>>is being operated but it's not doing anything.
>>>>>
>>>>>I guess something has come unhooked.
>>>>>
>>>>>Is it likely to be something I can get at and re-hook fairly easily?
>>>>>
>>>>>Thanks,
>>>>>
>>>>>Tom
>>>>
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>>
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> 
> 
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