Hi Tim,
Thanks for the information, I have not start to worry about the supply
of mercury battery so I have not do any experiment on the battery
voltage to EV errors. I just heard from the list that a 1.5V cell can
give you up to three stops errors, that looks too much. If that is
true in such case a 0.1V different can give you more than one stop
error. With a current variation from few uA to 0.5mA I would expect at
least 0.1 volt voltage drop different from most diode I have seen
(Germanium and Schottky).
C.H.Ling
HI100@xxxxxxx wrote:
>
> chling@xxxxxxxxxxxx writes:
>
> << I have not measure the current draw by the OM1n at
> different lighting condition, but I expected the variation is very >>
>
> I posted measurements on this a long time ago if you check the archives. I
> was looking into various conversion options at the time. The diode option
> adds modestly ~0.3stop to linearity errors at high EV. The error at high EV
> is minimised if you calibrate full scale, ie. if you just use the MR9 you may
> have a bit larger error with no FS calibration. At low EV the battery voltage
> error is large but the EV measurement error is absolutely negligible because
> the error is a percentage of EV reading. The current variation is form a
> few uA leakage when dark up to about 0.5mA for a fast lens under bright
> conditions. Olympus specifies 0.8mA max in the service manual.
>
> Regards,
> Tim Hughes
> >>Hi100@xxxxxxx<<
>
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