Hi, looking further still, it seems the early Mamiyaflex Porrofinders
took the mercury 625 cells (the one I have) and later models took
the S76 silver oxide, why the fellow said the battery cover had
S76 marked. I'll just get a Wein air cell replacement.
Rich
On Fri, Dec 9, 2016 at 11:04 AM, CLIP <clip@xxxxxxxxxxxxxx> wrote:
Sorry Tim, someone else can't type! Here is the link.
http://tinyurl.com/ndrvsbs
Clifford.
-----Original Message-----
From: pure-silver-bounce@xxxxxxxxxxxxx [mailto:pure-silver-bounce@
freelists.org] On Behalf Of Tim Daneliuk
Sent: 08 December 2016 23:04
To: pure-silver@xxxxxxxxxxxxx
Subject: [pure-silver] Re: Battery for Mamiyaflex Porrofinder CdS
On 12/08/2016 04:23 PM, Richard Lahrson wrote:
I just spent some time locating the right battery: S76.
Fortunately, not a mercury type. Someone had one with the info on the
battery cover that was not on mine.
Rich
<Longwinded dissertation on merc battery replacement follows>
On occasion, I rescue old lightmeters and cameras that were built to use
the older mercury batteries. These batteries had a nominal 1.35 volts
rating, as opposed to the newer batteries which are 1.5 volts. Moreover,
the mercury batteries mantained there voltage until just before they died,
whereas modern alkalines' voltage degrade slowly over time. This gradual
degradation from too high- to too-low a voltage makes light meters lie - a
lot in my experience. You'll start out massively underexposing and end up
overexposing. I've seen errors at well over 1 stop.
You can use modern silver oxide batteries because they fail like the old
mercury's - the hold voltage until the very end. But ... they're still 1.5
volt devices.
In some cases - like LunaPros - I just take them apart and recalibrate
them against a known good meter using the higher voltage from an S76
battery.
But ... the slickest solution I've seen is from CRIS Camera Repair. They
sell adapters that take a modern silver oxide hearing aid battery, and
regulate the voltage down to the nominal 1.35 volts the old cameras
expected. The adapters are machined to fit right into the same space as
the original battery. At $40-ish, they're not cheap, but for something
you really treasure (like all my old Nikons and my Yashica MAT-124G) they
work just great:
http://shop.criscam.com/collections/mercury-battery-adapters
--
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Tim Daneliuk tundra@xxxxxxxxxxxxxx
PGP Key: http://www.tundraware.com/PGP/
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