Sorry Moose but the OM2 has 2 CdS cells in the viewfinder. The SBCs are at
the bottom of the mirror box and used ONLY for auto.
Julian
----- Original Message -----
From: "Moose" <olymoose@xxxxxxxxxxxxxxx>
To: <olympus@xxxxxxxxxx>
Sent: Tuesday, September 28, 2004 11:07 PM
Subject: [OM] Re: OM Metering
> Julian Davies wrote:
>
>>That's the curtain design, not the meter weighting.
>>
> Yes, but which meter? There are 2 entirely separate metering systems in
> the OM-2(n).
>
>>The horizontal component of the centre weighting comes from the curtain,
>>the
>>vertical component from the design of the meter array, with an overlap of
>>the fields of view of the two SBCs, if I remember my Pangerl correctly -
>>don't have it to hand.
>>
> Again, though, you aren't addressing the difference between Auto and
> Manual. What you propose assumes that the 2 systems are somehow
> overlapped or averaged. The SB cells have no effect on Auto exposure at
> all, it is entirely controlled by the cell on the bottom of the mirror
> box. Also, the curtain pattern has no effect at all on the SB cells, as
> they see only what is on the viewfinder screen. Thus the curtain pattern
> change changed Auto exposure shots from horizontal center weighted to
> overall average, but has no effect on the viewfinder metering system.
>
>>When the curtain changed, the meter array did not, leaving the metering as
>>a
>>vertical line preferred.
>>
> This would be correct for Manual mode only, if the curtain pattern
> change affected that system, but not for Auto. I can't really believe
> that viewfinder metering, the only metering for manual use, would have a
> vertical pattern. One of the primary reasons for center weighted
> metering in the firat place is to avoid underexposure of subjects due to
> influence of the sky. Horizontal center weighting makes some practical
> photographic sense in many circumstances, vertical makes none at all.
>
> I've always assumed that the curtain pattern change was driven by 2
> issues. First, and most important, it won't work well in portrait
> orientation outdoors with sky and will give different exposures of the
> same subject with different camera orientation. Second, it could lead to
> exposure inconsistencies in mid range speeds where some of the metering
> is off the curtain and some off the film.
>
> Moose
>
>
>
> ==============================================
> List usage info: http://www.zuikoholic.com
> List nannies: olympusadmin@xxxxxxxxxx
> ==============================================
>
==============================================
List usage info: http://www.zuikoholic.com
List nannies: olympusadmin@xxxxxxxxxx
==============================================
|