On 7/19/06, Chuck Norcutt <chucknorcutt@xxxxxxxxxxx> wrote:
>
> Now for stopping-down lenses.
>
> OM's have an automatic diaphragm as do pretty much all cameras of that
> era or later. On an OM when you set the aperture on the lens to, say,
> f/8 the lens doesn't actually stop down. It stays wide open so you can
> see to focus better. It doesn't' actually stop-down to your setting
> until you press the shutter release.
>
> But the stop-down mechanism is mechanical and part of the camera.
> Putting the lens on another brand of camera leaves no means for the lens
> to be stopped down. When adapting the lens to another camera the
> adapter needs a pin that engages the stop-down lever on the OM lens.
> When you attach the lens to the adapter that pin will engage. Now when
> you change the aperture the lens will close down or open up immediately.
> Also, when you meter the exposure the metering will take place at the
> shooting aperture. Normally it would take place wide open and the
> camera would adjust the reading for the expected actual shooting
> aperture. Since the new body has no connection with the aperture of the
> lens it can't know how it's set. But metering at the shooting aperture
> is OK. It's just that the viewfinder is darker. If you focus wide open
> to get a brighter image you need to remember to stop the lens down to
> the shooting aperture before taking the shot if you haven't already done
> that to get a meter reading. It's a habit that must be acquired. I
> always forget.
>
>
That's really analytic! Thanks Chuck.
At some point I might try this 'hybridisation' and show here the results,
I'm quite curious indeed. Although I must say that the ergonomic advantages
of the OM-System cameras (light, small and bright viewfinder) are almost
irreplacable for my particular needs.
Christos
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