The pulse frequency is 20HKz, should be fast enough. I think the pulse
duration and power will vary according to shutter speed. It may not
have too many variation but at least two for OM4Ti/3Ti and another two
set for OM707 since the flash has different GN for OM707.
C.H.Ling
Tim Chakravorty wrote:
>
> >Therefore, for an "FP" flash to work, it must always have
> > the same, long burn duration, regardless of shutter speed.
>
> I think you are assuming that the flash remains ON for the entire time it
> takes the slit to traverse the focal plane. That
> may not be true. I remember reading somewhere that in super sync mode the
> flash output is not continuous but
> a series of pulses. How many pulses would that be.. If we divide the length
> of the rectangular focal plane by the
> width of the slit - that gives us the number of slits that can be fitted all
> at once on the plane. And since we want
> illumination in 'all of the slits' there will have to be so many flash
> pulses. In other words, the flash fires every time
> the window moves a distance equal to its width.
>
> Now lets say the length of the focal plane is about 36mm. The max syn speed
> with a regular flash is 1/60 sec.
> The window therefore moves at a constant speed of 36x60 ~ 216 cm/s . If the
> shutter speed is any higher than
> 1/60s the slit only narrows but still moves with the same speed. IMO a flash
> duration of 1/60 s is too long, they
> typically go from 1/500s and up, and is why its pulsed.
>
> -Tim
>
>
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