An invention that definitely comes from East German screw-mount Prakticas is
electronic
transmission of information about the aperture set from a lens to the camera: three
contacts provided this information, albeit it was non-digital communication based on a
resistor. Pentax much improved such communication in A-series lenses and cameras and
raised it to digital level.
Tom Rittenhouse <[EMAIL PROTECTED]> napisał / wrote:
> I am not sure about "automatic stop down" which appeared in
> the late fifties, but Pentax is the originator or the
> "automatic reopen aperture", the "instant return mirror",
> and the "behind the lens meter". Pentax had a history of
> inventing SLR inprovements and licensing them very cheaply
> to other companies. Sometimes to the point where the other
> companies had them on the market before Pentax.
> --Tom
>
>
> "Juan J. Buhler" wrote:
> >
> > On Fri, 15 Jun 2001, Tom Rittenhouse wrote:
> >
> > > Actually it is a "Practika screw mount". Pentax did not
> > > invent it they adopted it from the german cameras. That
> > > ain't bad, it just means there are more lenses available out
> > > there than you though. M42 is the generic name for the
> > > mount.
> >
> > Yup, you're right, although I've heard "Pentax SM" more often than
> > "Practika SM."
> >
> > BTW, was the implementation of automatic aperture on these lenses also
> > invented by someone else? Was it standard?
>
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>
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