jj
----- Original Message -----
From: "Daniel J. Mitchell" <DanielMitchell@xxxxxxxxxxxxx>
To: <olympus@xxxxxxxxxxxxxxx>
Sent: Tuesday, October 09, 2001 12:47 PM
Subject: RE: [OM] OM-2Sp flash LED question
> > O.k., your description of the way the T20 works with your camera
indicates
> > that the T20 flash properly lets the camera know that the flash exposure
> was
> > correct (or not when "under" lights up).
>
> Ah, so it works that way around.. I thought it worked like this:
>
> 1. Flash tells camera it's charged, pin A goes high. I take picture.
> Shutter opens.
> 2. Camera tells flash to start firing, raises pin C.
> 3. Flash says "okay, I'm firing", pin B goes high.
> 4. Camera watches light coming in.
> 5. Camera decides it's had enough light.
> 6. Camera lowers pin C.
> 7. Flash stops.
> 8. Shutter closes.
>
> If the flash had enough oomph, then pin B is still high when pin C is
> lowered, so the camera knows that everything was okay. If the flash didn't
> have enough power, pin B will fall sometime between 4 and 5 above, so the
> camera knows there wasn't enough and can light the 'under' warning.
>
> > Now, initially I was thinking this flash simply doesn't transfer an
> > "exposure o.k." signal to the camera, but...
>
> So TTL flash uses the camera to start/stop the flash, but relies on the
> flash itself to tell the camera if there was enough light? That seems
> peculiar to me; am I misunderstanding things?
>
> > ...for this I don't have any logical explanation! The only thing I can
> think
> > of, is that perhaps the Miranda flash does not fit as snugly in the
flash
> > shoe as the T20 does, hence causing the "exposure o.k." contact between
> the
> > flash and the camera to not be o.k. Still this would not explain why
under
> > specific conditions it does work and under others not, unless this is
mere
> > coincidence.
>
> Well, I'll try cleaning the contacts and see what it gets me -- it
> certainly doesn't fit as nicely as the T20 does, but it doesn't seem to be
> obviously loose, and the pins all look clean to me.
>
> > How often did you try this?
>
> Lots of times.. I also changed the batteries in the flash and tried
again,
> no change there.
>
> -- dan
>
> < 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 >
>
< 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 >
|