That's a very good explanation as far as I can make out Daniel.
However, the fact remains that whatever the tabs are doing, whatever
the sort of lens or extension tube, the OTF system, when the camera is
set to Auto, will close the shutter when there is enough exposure on
the film according to how the ASA is set. This is what Donald was
getting at in reponse to Piers' post.
Chris
On 5 Dec 2003, at 19:36, Daniel Sepke wrote:
All OM AUTO aperture lenses have two levers on the rear of the mount.
One
shuts down the aperture to what ever setting you have chosen. The other
tells the exposure control system in the body information about the
lenses
aperture setting. As the aperture only gets shut down as you are
taking a
picture the meter need to know how much bias its reading from the
fully open
aperture. If no bias was applied the meter reading would only apply to
the
fully open aperture of the lens you are using.
snip
On Fri, 5 Dec 2003 08:56:55 -0000, "Piers Hemy" <piers@xxxxxxxx>
wrote:
There is a tab on any OM mount lens which reports the aperture set on
the
lens. If you don't have a pin engaged with the aperture reporting
cam on
the body, you will get up to 6/7 stops overexposure. Try a 7mm manual
extension tube, which has the fixed pin to do the necessary.
Is this really so? I thought the great beauty of real-time OTF
metering was that it simply integrates the light received by the film,
and closes the shutter when it's done (or quenches the flash if one is
attached). It shouldn't matter about coupling pins or anything else in
auto mode. Manual metering - that's another story!
Am I right? Perhaps John H could chip in with his wisdom!
Regards
John Gruffydd (Mold, Wales, UK)
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