----- Original Message -----
From: "Eric Goldstein" <egoldste@xxxxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Saturday, May 03, 2008 8:17 PM
Subject: [rollei_list] Re: OT: Replacing Mercury Cells in a
Nikon F
They are cheap but they are very unpredictable. They have
a short life
when activated and there have been many reports of these
cells being
sold from outdated stock, rendering them of little use. So
the problem
is you can carry lots of spares with you and still be out
of luck...
Not my idea of a good solution but others seem OK with
them...
There are now exact sized replacement SO cells for the
625, so if you
can simply recalibrate the device for the voltage
difference, this may
be a better way to go...
Eric Goldstein
Thats just the problem, you can't "recalibrate" because
the error depends on the voltage and that is not constant
for most types of cells. The great virtue of the mercury
cell is that its voltage curve is very flat. That allows
using the cell without a regulator. Regulators in general
dissipate some of the energy in the cell so, if its possible
to do without one its desirable.
My solution is a makeshift. I have no idea how long the
cells will last but the meter has a definite check point so
there is a positive indication if the cell voltage changes
much. This gives me a simple and cheap way to keep the TTL
lightmeter in this camera going, at least for the present.
I have a junk finder so I can see if there is room in it
for some sort of regulator. That would allow using alkaline
cells although they are not long lived compared to mercury
cells either.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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