Archived posting to the Leica Users Group, 1999/03/28

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Subject: RE: Antw: [Leica] Autofocus & Leica
From: Alan Ball <AlanBall@csi.com>
Date: Sun, 28 Mar 1999 19:15:15 +0200

Nathan,
I do not know the PZ1-P, but I have used the previous generation (SFXn) and 
tried the current ZX5n. Both offered focus confirmation with M42+K adaptor, 
K and KA lenses. It is a basic feature: you watch the focus indicator on 
the viewfinder LCD and get a full dot (if I remember well) when you hit 
what the camera considers as the point of focus. A useful feature is to 
activate the beeper: the body will beep when you hit the point of focus. 
I'd be very surprised if the PZ1-P did not offer that feature. Try it with 
beeper on, as the AF sensors are very sensitive, and the visual 
confirmation will only appear when you are perfectly on focus (with subject 
in the AF sensor frame). It is easy to miss the dot, as a millimeter or two 
past the point, it will not show anymore.

More sophisticated focus confirmation systems like the Contax RX offer a 
scale, roughly indicating how far out of focus you are. I  tried it: it 
does not work fast enough as to be of any interest. The Contax SLR lenses 
have no electronics at all BTW.

The Nikon F501, F80(n), F90(x), F4, F5, and probably others as well, offer 
focus confirmation with AI lenses.

Focus confirmation on the Leica R would probably be similar to the RX, 
hoping it will react much faster though. There is no 'reasonable reason' to 
believe that the ROM would be necessary for that feature.

Alan

On dimanche 28 mars 1999 16:19, Nathan Wajsman 
[SMTP:nathan.wajsman@euronet.be] wrote:
> Alan,
>
> I am confused...my Pentax PZ1-P does not provide any focus confirmation 
when I
> mount a Pentax K mount lens on it. I realize that it is not in the same 
class
> as Nikon F5, but it is after all Pentax's top-of-line SLR and not cheap. 
Am I
> missing something really simple?
>
> Nathan
>
> Alan Ball wrote:
>
> > Lucien,
> >
> > As a matter of fact, ALL autofocus bodies provide focus confirmation 
with
> > compatible mount, manual, electronics free lenses (most Nikons and all
> > Pentax show complete backward compatibility in that respect). AFAIK, 
you
> > will also get focus confirmation with a Leica R or a M42 lens mounted 
on an
> > EOS body. There is no need for electronics in lenses for focus 
assistance
> > applications: the sensors are in the body and they telemeter points as 
they
> > will appear on the film plane. Electronics come in handy for 
sophisticated
> > TTL flash management, and, depending on the supplier's architecture,
> > reliable, non-mechanical, interactive management of the iris.
> >
> > Alan--
>
> Nathan Wajsman
> Overijse, Belgium
> Photo page: http://members.tripod.com/belgiangator
>
>