cederberg@xxxxxxxxxxxxxxxx wrote:
Greetings all.
Just wondered what that little guy inside my OM-2 does in Auto Mode.
Lets say that I'm standing with the sun behind me on a sunny day.
I've set my lens on f/8. The needle in the exposure meter hovers between
1/250s and 1/500s. I then push the shutter release.
Will the picture be taken at f/8 and 1/375s?
Roughly, yes. The OM-2(n) has 2 completely separate exposure meters. The
one that you see through the viewfinder is for manual use and to show an
estimate of the exposure in Auto Mode. A completely different TTL system
takes over as soon as you press the shutter release in Auto and the
mirror flies up. This system reads reflected light off the pattern on
the first curtain and the film itself. As soon as enough light has been
received to properly expose the film, the second curtain is released.
This system has extremely fast response, and also works in TTL Auto Mode
with the T series flashes to quench the flash when enough light has
reached the film.
If the light changes significantly while the shutter is open, the actual
shutter speed may be different from what the other system showed. If the
camera has not been adjusted for a long time, the 2 systems can be out
of synch. The TTL will still give correct exposure, but it may not be at
quite the speed you think.
Moose
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