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[OM] Re: [OT] changing the foam of a Canonet QL17

Subject: [OM] Re: [OT] changing the foam of a Canonet QL17
From: Manuel Viet <oly@xxxxxxxxxx>
Date: Thu, 27 Apr 2006 09:59:19 +0200
Le jeudi 27 Avril 2006 05:05, Moose a écrit :
> Manuel Viet wrote:
> > ...............failures aside, the battery is
> > also a problem, because the camera used the ill-famed px625 rated at 1.35
> > V. This battery being prohibited, there is no easy solution : alkaline is
> > 1.5 V (and has a steep discharge curve where the old mercury 625 had a
> > flat one), zinc-air cells are of a different form factor (and last only 2
> > month), Wein-cells (they are really Z-A, but made to replace the 625) are
> > expensive, have short lives, and are not sold everywhere. For my test
> > purpose, I bought an alkaline 625 and played with the ISO dial ; my QL17
> > being a 'L'(uxury) one, it has a check button moving the exposure needle
> > in the viewfinder, so It gives me a near-real time proportion between the
> > actual charge and compensation required of the ISO scale (the test
> > originaly was to check if the needle was in a zone near the middle of the
> > scale ; but with a higher voltage, the needle goes farther, and you can
> > guess the initial underexposure by computing the difference beween the
> > aperture reached and the "normal" center position - this test needs to be
> > carried on regularly to ensure consistency).
>
> Wouldn't it be much easier to use an MR-9 adapter with sliver-oxide
> battery? Correct voltage, long life with flat voltage curve, what's not
> to like?.

The curve is only flat under intensity constraints ; that's the Schotsky 
effect, or so was I told (by my uncle who is an EE, and btw worked in the 
company where Mr Schotsky was). If the intensity goes off bounds, the output 
voltage is no more straight and your exposure is wrong without warning. Not 
to say the adapter is a completely bad idea, with an OM-1 it's the best 
solution, but the QL17 provides a means to make accurate exposures with just 
a bit of care, so...

-- 
Manuel Viet

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