How about turning this adapter thing around ?
What if you used a mechanical stop down for the lens (e.g. like the cable
release in the bellows) and just trigger the shutter (micro switch) once the
lens has closed down to the set aperture. You could just incorporate a
cable release socket or a separate button/lever on the adapter. End result
is no servo required and no complex circuitry.
...Wayne
> -----Original Message-----
> From: Ken Norton [mailto:ken@xxxxxxxxxxx]
> Sent: Friday, 23 September 2011 1:54 AM
> To: Olympus Camera Discussion
> Subject: Re: [OM] A Worthwhile Olympus Accessory
>
> > Well, let's take that thought and step back to the adapter ring
> itself.
> > You have about 1/8" inside diameter that you can fill, and there's
> nothing
> > that says you can't have an extension of the outside diameter along
> the
> > bottom 30-60º. You just can't easily make it thicker along either
> portion
> > and expect to accomodate all OM base lenses. That could provide
> enough
> > volume to accomodate an electromagnetic actuator.
>
> Prior to m43, I thought this would have been a potentially viable
> project.
>
> >From what I've seen, the electronics for a Four-Thirds lens is just
> under the lens-mount plate. In fact, I've seen one example where the
> screws of the mount actually pass through the circuit board. As a
> standard 4/3-OM adaptor is so thin, we'd have to take this circuit
> board and move it outboard. If, in fact, we'd be able to keep it
> stuffed in there, we'd have to make room for the actuation lever from
> the outboard servo. With m43, we would have more than enough space.
>
> Actually, with m43, the one thought I had was to take the entire back
> half of the lens, remove the optics entirely, saw it down to length
> and secure the OM mount flange on the front of it. I don't know how
> powerful the servo in the lens is for aperture shutdown in these
> lenses, but the servo is tiny. We might be able to scavange servos
> that fit inside this FrankenAdaptor. If not all the way inside, at
> least most of the way inside. Obviously, metering is going to be
> hosed. The camera would have no idea where you placed the lens
> aperture. So manual exposure would be required. But the big advantage
> to all this is wide-open focusing.
>
> Why is it that I feel like we've stepped back to the 1950's all over
> again. Didn't SLRs before the Nikon F generally have this problem?
>
> Maybe it would be easier to scavange a digital body to make a digital
> film back for the OMs. The Sony is almost thin enough.
>
> AG
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