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Re: [OM] om2sp

Subject: Re: [OM] om2sp
From: Garth Wood <garth@xxxxxxxxxxxxxxx>
Date: Wed, 22 Mar 2000 08:33:00 -0700
Cc: <rikard.bjorklind.4077@xxxxxxxxxxxxx>
At 11:48 PM 3/21/00 +0100, Rikard Björklind wrote:

[snip]

>Everyone says that silver oxide batteries is better than alkalines. But
>how much better are they? I've been using the same pair of alkalines for
>two years now (with my OM-2), and I recently put them in the OM-2sp, and
>they are working fine there.
>Is it worth it too search for silveroxide? At least here in sweden the
>alkalines are easier to find :-).


Rikard:

As some other List members have noted, alkalines have an annoying tendency to 
fail during exposure, even though the battery indicator says "good."  This 
tendency, as far as I can tell, is increased during cool/cold weather.

The reason for this has to do with the different internal resistances (and 
therefore different internal peak current flows) of alkalines vs. silver 
oxides, combined with the differing discharge curves of the two types of 
batteries.

Silver oxides combine two very desirable characteristics in a battery which 
powers a magnet (which is essentially what's happening when the OM-2sp keeps 
its shutter curtain open for a specified period of time): a relatively flat 
discharge curve over a wide range of operating temperatures, and a relatively 
low internal resistance, which allows it to provide high current pulses of 
energy for short periods of time.  Thus, a silver oxide, for most of its 
operating life, maintains a voltage quite close to 1.55v (very important as a 
reference voltage for the exposure circuit), and can deliver the milliamps when 
they're most needed, that is, when the shutter curtain is open and sucking 
amperage.  Alkalines, by contrast, share *neither* of these desirable 
characteristics to the same extent as silver oxide in an identical form factor 
(button cells).  That's why silver oxides are "better" for the application 
you're interested in (keeping the OM-2sp happy).

So yes, if you don't want to risk having your OM-2sp "crap out" just when 
you're going for that once-in-a-lifetime shot, silvers offer better insurance 
in this regard.  (Nothing's perfect, though.)

Garth


  
"A bad day doing photography is better
  than a good day doing just about 
  anything else."
  
The Unofficial Olympus Web Photo Gallery at:

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