Exposure times in the 2 are adjusted with the led in use, so times are
accurate. If the led were off, times would be inaccurate. Exposures with
the 2 are ASA based. the lower the ASA, the longer the shutter can stay
open in low light. ASA 12 exposure (I think) was under 20 minutes, ASA 1600
maximum was about 20 seconds.
John Hermanson
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----- Original Message -----
From: <HI100@xxxxxxx>
To: <olympus@xxxxxxxxxxxxxxx>
Cc: <thomas.bryhn@xxxxxxxxxx>
Sent: Sunday, October 21, 2001 2:10 AM
Subject: [OM] OM Specs
| 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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