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Re: [OM] FIGHTING FINCHES + lens problem

Subject: Re: [OM] FIGHTING FINCHES + lens problem
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
Date: Fri, 06 Jul 2012 07:44:47 -0400
What Moose said.  See this ebay ad and its main photo
<http://www.ebay.com/itm/OM-adapter-to-Olympus-4-3-E-1-E-420-E-510-410-MF-1-repl-/290539337226?pt=LH_DefaultDomain_0&hash=item43a57e760a>

Note the small tab located at about the 8 o'clock position.  The purpose 
of this tab is to catch and hold the aperture stop down lever that 
protrudes from the back of an OM lens.  With the tab in place the 
diaphragm should close/open as you rotate the aperture ring.  The "tab" 
could be a pin or screw or something else.  It's action (or inaction) 
should be very apparent to you if you mount the adapter on the lens and 
peek at the back of the adapter off-camera as you rotate the aperture ring.

With the adapter off the lens the lens should close down when you press 
the DOF preview button (which has exactly the same effect as the tab on 
the adapter).  If the lens doesn't close down when pressing the DOF 
preview button you have an internal lens problem.  Possibly stuck 
linkage or oil on the diaphragm blades.

Chuck Norcutt


On 7/5/2012 10:09 PM, Moose wrote:
> On 7/5/2012 6:07 PM, Rick Beckrich wrote:
>> My fault for the original unclarity - I meant to say that turning the
>> aperture ring produces a nice "click"
>>
>> for each stop as you close down from f4.5, but - nothing changes in the
>> diaphragm - it doesn't stop down.
>
> On an OM body, setting the aperture ring doesn't stop down the actual 
> diaphragm, so you can view/focus at full aperture.
> The body activates the aperture stop down pin/lever on the back of the lens 
> as it puts the mirror up, so the actual
> exposure is at the selected aperture.
>
> Sounds like your OM=>4/3 adapter doesn't have a tab/pin/screw to activate the 
> aperture stop down lever/tab on the back
> of the lens. Or the activation piece is bent or damaged.
>
> Press the DOF preview button on the mount or move the stop down lever with 
> your finger. Each should bring close the
> physical aperture to match the ring setting. If the lever works, the problem 
> is with your adapter.
>
> Ring Around the Aperture Moose
>

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