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Re: [OM] Why Oly is in a hole / screens & 280 flash

Subject: Re: [OM] Why Oly is in a hole / screens & 280 flash
From: VELUWEH@xxxxxxxxxx
Date: Mon, 20 Jul 1998 06:30:06 -0400
Shawn Wright wrote:

>I'd have to say that Hans view
>doesn't *sound* correct either, according to my understanding of the
>F280. If the 3-Ti could turn off the flash in FP mode, as it does in
>mode at 1/60 or less, this would result in part of the frame receiving
>*no* flash exposure if the shutter is above 1/60 (why else would one
>use FP mode). It's my understanding that the whole point of FP is that
>the flash consists of many short bursts such that they appear as a
>continuous light source to the film, even at 1/2000 sec. Cutting off
>the flash (as TTL does) would reduce the FP mode to TTL-equivalent, and
>its inherent limitation of approx 1/60 max shutter speed.
>That said, I suppose this must mean that the 4-Ti /F-280 must calculate
>the required FP flash intensity/shutter speed prior to exposure, since
>varying *either* of these values during exposure would also result in
>uneven exposure across the film plane. (again assuming shutter speed
>above 1/60) Which explains why the 4Ti *cannot* vary the shutter speed
>during exposure.

The camera *can* control the Super FP flash duration. The duration,
which seems to be related to the flash burst frequency, can vary when
controled from an OM-4Ti or OM-3Ti between 1/25 and 1/50 of a second;
when controled by an OM-707 it can be between 1/30 and 1/70 (this is
related to the faster shutter of the OM-707). So "cutting off" the FP
flash wouldn't have the unwanted effect that part of the film doesn't
get any flash, but changing the frequency (flash burst) would result in
uneven exposure. After re-reading the FP-FAQ at


and reading this new link


I must admit that there still is much confusion. If the OM-4Ti would
pre-set everything (flash duration, flash burst and shutter speed)
where does OTF/OTC go?
While the first link suggests that everything is pre-set and the only
*auto* working FP combi is from M*n*lt*, this new link suggests that
the duration is fixed (pre-set) when the camera is set to manual (and
obviously on the OM-3Ti too), but when used in Auto mode on the OM-4Ti
it says the '280FP is in control of the camera'. Well, they probably
work closely together.

BW wrote:

>All I have for reference is my 3Ti instruction
>manual and a 280 instruction manual dated (0491) so it does not list
>fairly new 3Ti. Per the chart, (wait let me get my 3" magnifying glass,
>I think it is around here somewhere) Auh yes. With ISO 100 @ 1.5m =
>@ 1/2000sec+; 1/1000sec @ f2.8; 1/250 sec @ -f5.6.

This complicated table in the OM-3Ti manual doesn't sound very
practical to me. But doesn't is contain exactly the same data as can be
read from the graph in the F280 manual that shows the relation between
aperture, working distance and shutter speed? This graph is also
provided with a text that says the data are based on the absence of
available light... BTW, this chart is published by Tomoko:


When working with the OM-3Ti (or OM-4Ti in manual mode) and Super FP, I
guess the only safe thing you can do is setting shutter speed and
aperture according to the background that won't recieve flash anyway,
check if the foreground lies in the flash working range, and *hoping*
the flash doesn't overexposure the foreground. For more fill in flash
control, I would use a Metz or Olympus T-series flash in computer mode
(=Normal Auto mode) anyway.


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