Hi Chuck, John and all,
> From: Chuck Norcutt
> If there was a direct mechanical connection on closing of the blades then a
> lens whose blades were completely stuck open (John's "extreme case") would
> cause the camera to jam and the aperture activation arm in the camera would
> be blocked from operating. It could not rise up and move the diaphragm lever
> in the lens, the mirror couldn't rise and the shutter couldn't fire.
That's the expected behaviour. You may try it, hold tightly the
auto-diaphragm lever on the body (lens removed) while pressing the shutter
button -- it won't fire and will remain cocked. If with the button pressed
you left the lever go up a bit, the mirror will also flip partially. If you
put it down again with the button released, shutter will remain cocked too.
From: John Hermanson (omtech1verizon.net)>The rear lens stop down ring does
push on a
>lever inside the lens. This lever with a long
>slot (ZD3030) has a pin riding in it (arm of
>ZJ1031). That pin slides to a spot determined
>by position of f stop cam, then spring (CB0868)
>is free to pull diaphragm plate to stop blades
>down. Levers only force other levers to a
>certain point in the block diaphragm, then
>parts rely on springs to pull them closed.
Well, that makes a lot of sense. On second thought, non-OM lenses put the
auto-diaphragm pin in _different_ position depending on the setting of the
aperture ring -- if already at full aperture, it won't move at all, would
keep at its extreme position. OTOH, Zuiko's pin will move all the way
regardless of the aperture ring position.
Thanks, John, I stand corrected!
> I've
>never seen a lens of this design that had so
>much oil that diaphragm did not close but I
>think it could happen.
Seems to be fortunate for Zuikos, while non-OM lenses are much more
sensitive to oil... As already said, my oily Zuikos have no trouble closing
the iris for a proper exposure. The 50/1.2 just takes a little longer to
shoot, but it may be caused by a different flaw -- just a stiff pin.
Cheers,
--
Carlos J. Santisteban Salinas
IES Turaniana (Roquetas de Mar, Almeria)
<http://cjss.sytes.net/>
--
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