Thomas wrote:
>>
Let me see if I got that: The P board cuts off power after ~3.5 minutes,
this board is easily accessible and can be modified, but should not be
taken to extremes.
The "LED limiter", is that simply a LED that shines on the meter cells
after the P-board has timed out, or are there two separate limiting
mechanisms?
<<
When the timer times out it switches on the LED and it's light output is then
integrated by the photocells. When they have recieved enough light the
shutter trips just as if the light had been reflected off the film. This
does lead to two times a long time from the main timer and a shorter time
that depends on the ASA set The OM2 of course does not have the first timer
but uses a lower level of light from the LED. So in one sense the OM2 always
has an incorrect exposure since the LED affects all exposure times. It is
just that the error is negligbly small for exposure times less than some 10's
of seconds. On the OM2 the error when the limiter causes a shut off at say
2minutes is probably typically of the order of one stop. i.e. the limit might
be 4minutes in pitch darkness and in the prescence of low light the
combination might be 2minutes. In reality, film reciprocity causes an even
larger error unless you dial in some compensation.
Regards,
Tim Hughes
>>Hi100@xxxxxxx<<
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