At 20:10 6/11/02, Andrew Tierney wrote:
Hi,
I've got a T32 flash which doesn't appear to work properly in full auto
mode on an OM 2N...
When used in Normal Auto on an OM 1N and OM 10, the autocheck light
blinks, as does the viewfinder led after and exposure has been made.
This is proper behavior.
However, on the OM 2N it doesn't, indicating bad exposure, but in the
exact same situation.
Also, when the flash is in full-auto, the light does not blink either, and the
flash power does not seem to vary when using different apertures.
Do you have film in the camera? In TTL Auto with the OM-2[n,S] and
OM-4[T,ti], it meters off the film. The reflectivity of the pressure plate
isn't nearly that for film, often indicating under-exposure when it should
have put out sufficient light.
Seeing as the switch is in the same position for GN32 Manual operation and
Full auto, with the calculator the other way round, I presume that the
flash goes into OTF full-auto when the contact on the OM2N is detected. I
also presume that one of the two contacts tells the flash to turn off.
You've almost got it, but not quite. Of the three contacts, the large
center one is obviously the flash trigger. One of the other two smaller
ones is the flash ready and exposure OK contact. This is the one that is
used by the OM-10 and OM-1n to light up the LED in the viewfinder. The
second of the two smaller ones is the "flash quench" contact used for
TTL-OTF. It signals the flash to shut off when the body metering has
sensed sufficient light from the flash. This is why the switch is in the
same position as for "Manual" operation on the back of the flash. Unless
there's a quench signal from the camera body before a full dump occurs, the
flash gives a full dump.
Is the problem that the contact between the OM 2N and the flash is gone? What
can I do to check this?
First, if the camera has no film in it, get a roll of the cheapest film you
can find and load the camera with it to use it as a "scratch roll." I
sometimes forget to do this, and end up wondering for a couple of seconds
why the same thing happens to me when testing a flash that supports TTL-OTF
control.
If it still occurs with film loaded, then the problem could be in the T-32,
in the OM-2n accessory shoe (you are using a Shoe 4, right?), or in the
OM-2n itself. At this point it's an ambiguity group. You'd need another
"golden" T-20 or T-32, and another "golden" Shoe 4 to isolate it further.
-- John
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