Remember that all batteries vary their voltage with load, age, use,
temperature, etc. Values given are nominal, i.e. about the average
produced over the useful life with the load designed for within
specified operating temperatures. As John and others have pointed out so
often, 357s are superior to other batteries with the same size, shape
and open circuit voltage because of the way they react to load and use
in the use to which we put them, powering our cameras. The Wein cells
probably do have an average voltage under the load of camera exposure
and over their useful life of about 1.35v.
Remember that none of the numbers we use are exact. Film speed varies
from batch to batch, with age, with temperature, with length of
exposure. Most lenses list their speed as approximate f-stops and say
nothing about their actual T (transmission) 'stop'. Less light gets to
the lens from a complex lens with many elements than from a simple lens.
Shutter speeds are only within a tolerance and vary with age,
temperature, orientation, etc. And so on and so forth. Most of the time,
all the variables are pretty close to theri nominal values and some vary
in one direction and others in the other and everything works. Sometimes
they all lean one was and we get bad results and tear our hair out
'cause we can't find the (one) thing that's wrong.
Long rant, short answer, something close to 1.35v will work fine almost
all the time.
By the way, the forward voltage drop across a typical small power diode
is about .2v. One of these days, I'm going to try one in series with a
357 to power an OM-1. I suspect that may be most or all of the active
circuitry in the MR9 adapters. The advantage over a resistor is that the
drop is consistent over a huge range of voltage and current and doesn't
use up battery power heating up a resistor.
Moose
John Hermanson wrote:
It works fine but the ones I've tested are 1.4V.
John, I don't wish to be a PITA, but for the record the battery packaging on
my Wein Cell states the voltage is 1.35v - which is exactly what the old
mercury battery output. It works fine for me.
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