William Sommerwerck wrote:
<<OTF Flash (OM-2n, OM-3Ti, OM-4, OM-4Ti):
1. First curtain begins to open, meter starts accumulating exposure off
of the film and curtain
2. First curtain fully open - Flash fires
3. Meter quenches flash and starts closing the second curtain when
sufficient exposure is measured (or flash fully discharges)
4. Second curtain closed - effective shutter speed 1/60
This isn't the correct sequence. You're combining ambient exposure with
the flash exposure. You definitely DON'T want the shutter closing when
the proper flash exposure has been reached.>>
I'm not sure I understand this. Of course you're combining ambient exposure
with flash exposure. As soon as the first curtain begins to open, exposure has
started although the flash has not yet fired. As soon as the first curtain is
fully open (which I assume takes 1/60 sec on OM cameras) the flash fires...
exposure continues after the flash is quenched and the second curtain is
closing. Admittedly, the ambient exposure is probably small, but it is there.
That's why you can get ghost images of a fast moving subject. I think.
I also don't know why you wouldn't want to close the shutter when proper flash
exposure has been reached. What's the alternative? You can't start closing
before the flash is quenched, and why would you leave it open longer?
<<In OTF flash mode, the shutter speed has to be 1/60 or slower, or the
flash is inhibited from firing. The sequence would be:
1. First curtain begins to open.
2. First curtain fully open -- flash fires.
3. Meter cell reads light reflected from film plane & circuit integrates
exposure.
4. When full exposure has been reached, flash is quenched.
5. Second shutter is released 1/60 after step #1, whether or not flash
has fired.>>
I don't see that this sequence is any different than what I said (or at least
what I intended to say).
More confused than ever...
Paul Schings
Coventry, RI
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
|