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Re: [OM] - Brighter screens and meter readings (reprise)

Subject: Re: [OM] - Brighter screens and meter readings (reprise)
From: flowerside@xxxxxxxxxxxx ()
Date: 2 Oct 2002 13:29:43 -0000

> The OM-2SP and OM-4Ti measure light through the same
> two SBC sensors in the light box during both viewing and 
> the taking of a photograph. When viewing, light is 
> measured through a semi-silvered section of the main 
> mirror, via an additional mirror that hangs down from the 
> back of the main mirror. 

After reading the OM-3Ti / OM-4Ti manuals which can be found on th e-sif site, 
I noticed that only the OM-3Ti manual (in the section "Creative Photography") 
explains - with a camera diagram - how does the center weighted light 
measurement work, and this involves passing the light through the semi-silvered 
mirror to the light sensor via the auxiliary mirror. Same procedure is used for 
the spot measurement, but the area metered is narrower as the proper diagram 
shows. 

Of course, in the OM-3Ti manual, there is no mention to the OTF light 
measurement method.

The diagram showing how to take the center weighted metering with the OM-3Ti is 
not reported on the OM-4Ti manual. In the latter one, indeed, there is a short 
description of the OTF light measurement method, but there is no direct mention 
to the metering  technique used when evaluating the shutter speed to show in 
the viewfinder. 

Should we suppose that, OTF measurement apart, the two cameras apply the same 
method when evaluating the shutter speed to show in the viewfinder in C-W mode, 
as your experience should suggest?

And for what concerns the two SBC cells which are supposed to be in the light 
box, how are they arranged? Does the sensor for the center-weighted estimate 
have a donut-like shape, with the smaller sensor (the one for the spot 
measurement) inside its "hole", or are they overlapped and the electronic 
circuit chooses which one to use depending on the metering mode? 

If this ain't the case, I can't figure out how can the two sensors be placed...

I know all this talking has no practical consequences, and I do apologize if my 
questions sound too repetitive, but I have to admit that I'm damn curious! :)

Ciao!

Fabio


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