The FTn meter required you to rack the f stop ring to minimum and maximum
aperture.
This automatically calibrated the asa setting. You had to set the asa
manually to
compensate for certain focus screens.
John
Camtech
Gene Mayeda wrote:
> This reminds me of the old Nikon Photomic T finder where you had to set
> the maximum aperture of the lens at the film speed in use in order to
> get the proper exposure readings.I think the early Nikkormats had a
> similar arrangement.Was this still a requirement of the FTn?Needless to
> say it made changing lenses less than effortless since not all lenses
> had the same maximum aperture.So I suppose that f-stops could be seen in
> the finder of future OM camera bodies but it would require one to set
> the maximum aperture in manually with the present lenses.Future camera
> bodies and lenses could be self-indexing while retaining compatability
> with the present lenses.
> Personally I never worried about f-stops in the finder.The more info in
> the finder there is the more I ignore it since it distracts me from the
> important business of capturing the "decisive moment".BTW has anyone
> here commented on how the apparent viewing area has decreased from the
> wonderfully large size found in the OM-1 and 2 to the smaller but
> information crammed 3 and 4? (Sorry I never looked inside a 2SP.)
> -Gene Mayeda
>
> Christopher Biggs wrote:
> >
> > CarlMarin <CarlMarin@xxxxxxx> moved upon the face of the 'Net and spake
> > thusly:
> >
> > > In a message dated 98-01-14 01:50:01 EST,Chris write:
> > >
> > > >
> > > > The ACTUAL aperture is not known to the body, only that the lens is
> > > > stopped down N stops.
> > > >
> > > > T
> > >
> > > Hi Chris,
> > >
> > > Of course the whole scheme is an analog by gosh and by golly sort of
> > > arrangement. I never really thought about this part of it before, maybe
> > > its
> > > a trick question. How does the camera know whether you've got a f1.2 or
> > > an
> > > f3.5 screwed on so it can give you compensated wide open correct
> > > readings?
> >
> > It doesn't care.
> >
> > When you are focusing you are at wide open. The camera measures
> > what's coming through the lens.
> >
> > If you stop the lens down one stop, IT STAYS WIDE OPEN, but the meter
> > moves by one stop. The aperture ring just tells the camera how many
> > stops it should fudge the reading by. Only when the shutter opens
> > does the lens actually stop down.
> >
> > You can easily fool the system by stopping down and pressing the DOF
> > preview on the lens. The meter reading in the camera will
> > immediately drop by the number of stops the lens is closed down, as
> > the actual light reaching the meter cell drops.
> >
> > > it's basically a case of the light coming thru the lens is the light
> > > coming
> > > through the lens and the body doesn't care, then why would something like
> > > my
> > > Tamron 500f8 mirror need an fixed aperture tab at all to get correct
> > > exposures
> > > out of the camera as it is shot wide open all the time, doesn't stop
> > > down?
> >
> > It should be fixed at the "wide open" position, yes.
> >
> > Even if you have a lens with no auto-diaphragm which stops down as
> > you adjust aperture, the lens simply needs a fixed aperture-reporting
> > lever and the TTL metering still works.
> >
> > The OM aperture arrangement is very very clever; it's only drawback is
> > (near) impossibilty of in-viewfinder aperture reporting.
> >
> > The lack of in-viewfinder display rarely bothers me, since I just
> > remember where I am. A quick spin down to f/1.8 and
> > count-the-clicks-back suffices to tell me the aperture.
> >
> > The only time it does bother me is doing macro work where I sometimes
> > can't get my head around the front of the camera (most recently
> > because of a nest of rose thorns) to see the exposure settings on my
> > OM-1 when I want to record them.
> >
> > Chris.
> >
> reated or destroyed during its construction or transmission.
>
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