On Tue, 4 Sep 2001 18:15:09 -0600 "Daniel J. Mitchell"
<DanielMitchell@xxxxxxxxxxxxx> writes
> Not exactly "on the market", but the flash I'm using is a Miranda "650
OM";
> says "olympus dedication" on the front. I got it used (UKP 10 = US$15
or
> so), so no instructions -- most of it makes sense, but I have a couple
of
> questions, in case it's similar to anything anyone else recognises: (I
> looked at the T32 instructions on om-sif in case they were relevant,
but the
> manual doesn't really tell me a lot; the OM-2S manual also just says
> "connect the flash, off you go" pretty much)
>
> There's a set of sliders on the back I can use to set the ISO speed
and the
> amount of zoom (W/N/S/T, wide/normal/slightly-zoom/telephoto, I'm
guessing)
> -- all these seem to do is move a little bit of plastic back and forth
which
> tells me the range and f-stop I should be using.
>
> The thing I don't understand is what the TTL/red/yellow/blue switch
does;
> it has "TTL" on the left, and "M/red/yellow/blue" on the top. The
sliding
> range guide implies that red = short range, blue = long range, fine --
so
> what does "M" stand for? Manual? I'd have expected that to be what I
set by
> setting the colours, though..
The colo(u)rs probably correspond to "normal auto" flash - controlled by
the flash's internal sensor. "M" is manual flash - in thsi position the
flash will always do a full dump of power. If this works anything like
the Olympus T flashes, and it sounds like it does, then "M" and TTL are
the same position on the switch. If the camera is in auto mode and the
flash is on M/TTL then a camera controlled TTL auto exposure will result.
If the camera is in manual mode then the flash will do a full dump.
>
> There's also a little switch on the bottom next to the connector
marked
> "M/TTL" -- again, I'm not sure exactly what this does.
Hmmmm this sounds a bit different than how the T flashes work. Perhaps
when the switch is all the way to the left you need to use the 2nd switch
to select manual or TTL?
> Experimenting with it, I find that if I set it to red, it recharges a
lot
> faster than if I set it to blue, and if I point it at near things it
> recharges faster -- so it seems as if the light sensor is working and
only
> putting out an amount of light based somehow on what I'm telling it
with the
> various switches (and the "check" light on the back of the flash
> will lightup/not depending on other things) -- but what I don't
understand is how
> these switches relate to stuff.
The different colors should correspond to a distance range and f-stop on
the ASA calculator panel (for normal auto operation)
>
> I also get various flashing things in the viewfinder when using it;
the
> green "ready" light shows up at the right time, and depending on what I
do
> it will say "over" or "under" at various times. I think; it's always a
bit
> dim to see the 'under' light, so I'm guessing that that's what it's
telling
> me. Why would it ever give me 'under', though? Surely the flash
> should stayon until it's illuminated things enough?
Only if it has enough power to illuminate the subject at the selected
f-stop. Typically the longest duration you'll get from an electronic
flash is about 1/1000 sec. If that isn't sufficient then you'll get an
"UNDER" reading. The fastest the camera can shut off the flash is about
1/50,000 sec - if that's still too much light you'll get an "OVER"
indication.
>
> How much influence does the camera have on this? Are the pins (three
metal
> ones, one plastic one) on the bottom of the flash just so the flash can
tell
> the camera what's going on, or do things go both ways?
The center contact is for normal X-synch. Of the other two conmtacts, one
is for the flash ready light and the other is used for TTL control of the
flash. I forget which is which, but I think the answer is in the FAQ.
Hope this helps a little,
Paul Schings
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