The silcone blue diodes in the 2/2N have tiny lenses on the front to focus
on the curtain area. I have seen 2s where one of the lenses had fallen
out, and it made auto speeds unusable.
The meter needle position is controlled by cds cells, 1 on either side of
the eyepiece, reading off the focus screen. The curtain pattern and sbcs
are for auto speeds only, as others have said.
John
----- Original Message -----
From: Richard Ross <richard@xxxxxxxxxxxxxxx>
To: <olympus@xxxxxxxxxxxxxxx>; <olympus@xxxxxxxxxxxxxxx>
Sent: Monday, October 18, 1999 1:05 PM
Subject: Re: [OM] OM2 w T-32 was (Fwd) OM-2 Meter
> At 10:37 18/10/99 EDT, Pauls0627@xxxxxxx wrote:
> >I always thought that the early OM-2 models were centerweighted when
> >measuring off the curtain, and full frame averaging when metering off the
> >film. So as shutter speeds got longer the amount of center weighting
> >gradually diminished. With the change to the new curtain pattern I
thought
> >the center weighting was somehow built in to the way the photo cells read
> teh
> >light, so there is the same amount of center weighting at all shutter
speeds.
> >
>
>
> It occurs to me that there is another aspect to this - in manual mode
don't
> the OM-2 and 2n use a different meter altogether, in the prism like the
> OM-1? So this business of shutter-curtain patterns presumably only
matters
> in auto mode.
>
> Photodiodes, like most sensors, have a sensitivity which varies according
> to the angle of incidence of the light, so if the metering diode has a
> fairly narrow acceptance angle then the metering will be centre-weighted,
> to some extent regardless of the pattern on the curtain.
>
> Richard
>
>
>
>
> Richard Ross
> Hemel Hempstead, England
> richard@xxxxxxxxxxxxxxx
>
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