Michael, some of your questions are answered in the Olympus OM SLR FAQ:
<http://brashear.phys.appstate.edu/lhawkins/photo/olympus.faq.html>
See, for example, B21 for the answer on determining the age of your OM
by decoding what's behind the pressure plate... not the serial #.
Mercury batteries were used because the voltage level is very stable
throughout the life of the battery and only falls suddenly at the end.
The stable voltage is critical to the exposure meter. Silver oxide
batteries also have a stable voltage througout their lives but, as far
as I know, didn't exist back then. The problem is that the inherent
voltage of the two technologies is different so the silver oxide has to
be stepped down from 1.55 volts to 1.35 volts to be used in the OM-1.
In JH's modification, as in the CRIS adapter, the stepdown is performed
by inserting a diode between the battery and meter. There is nothing
for you to adjust. This simple modification introduces some minor
inaccuracies at the extreme ends of the meter's range which have been
addressed in great depth by Tim Hughes (search the archives).
I'll let the FAQ and others address the remainder of your questions.
Chuck Norcutt
----------------------
Some questions bugging me for some time. Have just bought another
OM-1 to give to my daughter who is going off to her second country
(born a Kiwi here, she's also a Yank because I am) for the first time
in her 21 years, so I don't have to give her one of my two.
Please cc any rapid answers to me as well as list as I am on digest.
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