I suspect the adapter is not helping !
Most adapters will actuate the aperture stop down lever when the lens is
mounted to the adapter (some don't).
For a start, remove the lens from the adapter and looking at the rear of the
lens rotate the aperture ring.
One of the levers should move as you do this. Move the aperture ring to 16
and push the other lever with your finger, the actual diaphragm should then
close down fully. If this happens then there is no problem with the lens
Many people on this list recommend the adapters sold through the auction
site by "jinfinance".
> -----Original Message-----
> From: richard mcgrath [mailto:richardinvermont@xxxxxxxxxxx]
> Sent: Sunday, 11 April 2010 1:38 PM
> To: olympus@xxxxxxxxxxxxxxxxx
> Subject: [OM] Olympus OM Series adapters
> I purchased on eBay an Olympus Zuiko Auto-S 50mm F1.8 lens (the lens is
> marked "Made in Japan"), Serial No. 5870379. Although used, the lens
> appears to be in near-mint condition.
> I also purchased an adapter to fit this lens onto a new Panasonic DMC
> GF1 micro 4/3 camera body. I take pictures through a research
> microscope, through a telescope, and just for fun. In the first 2 of
> these cases, focus is critical. One of the main reasons for selecting
> this camera is the live on-screen enlargement capability (which is
> super) as a focusing aid. The adapter I have works ok as far as
> coupling the lens to the camera. There is, of course, neither "auto"
> nor electrical connection.
> Here's the problem, with the OM lens mounted on the adapter (or just
> holding the lens in my hand) the iris opens and closes smoothly, but
> only when holding the rectangular button on the side of the lens.
> Inside the lens is a spring-loaded articulator that are clearly
> designed for automatic control of the iris. If I hold this at its
> limit, it has the same effect as holding the rectangular side button,
> i.e. the iris opens and closes smoothly as the f-stop is changed. Left
> to its own devices, the lens stays wide open.
> Bottom line: I don't know if I have a lens that isn't working the way
> it should or if there's some function of the lens that I just don't
> know about or if I have an adapter that doesn't do what it should.
> It is clear that lots of folks use adapters to connect any number of
> lenses (including the Olympus OM Series) to any number of cameras. I
> have fair experience with Pentax, Sigma & Vivitar lenses, with adapters
> to paste them onto bayonet or screw mount cameras, and with adapters to
> paste cameras to telescopes and to microscopes, bellows & extension
> tubes. With the lenses I'm familiar with, you turn the diaphragm ring
> and the iris opens and closes---end of discussion. But I'm not familiar
> with this, my first Olympus lens, so a bad lens is a possibility. Is
> what I have described in paragraph # 3 above, the normal operating
> scheme for the OM Series lenses?
> I have a problem here and I'm hoping someone can make some helpful
> suggestions. My problem seems to point to the adapter. I need a good
> Olympus OM lens to micro 4/3 mount adapter and I don't think I should
> have to pay $150 to $250 for it. Can someone suggest a brand of adapter
> that works the way it should with OM Series lenses.
> Thanks in advance for your help,
> Options: http://lists.thomasclausen.net/mailman/listinfo/olympus
> Archives: http://lists.thomasclausen.net/mailman/private/olympus/
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