On Thu, 5 Nov 1998 00:03:37 +0100, "Per Nordenberg"
<per.nordenberg@xxxxxxxxxx> wrote:
>Thanks Frank for solving this query. It wasn´t the first time
>you´ve solved a mystery for us here on the list, and I gather it
>won´t be the last either. So it was the super FP capability that
>was the difference. Amazing. I´ve always thought the IS-3 had this
>too. I must admit I havent tried it out yet, but in light of this
>I certainly will as soon as I can. Here´s what my IS-3000 manual
>has to say about it:
>
>-quote-
>"Super FP Emission
>The emission time of a conventional flash is very short.
>So an SLR´s focal plane shutter can only synchronize with the
>flash at a slower shutter speed which allows the shutter curtains
>to be fully open. The IS-3000 has a new emission system called
>the super FP which makes the duration of emission longer, achieving
>full synchronization even at shutter speeds so fast that the shutter
>curtains are not allowed to fully open. The Super FP Emission is
>especially ideal for daylight synchro such as when the subject is
>backlit. This function lets you easily take natural looking
>daylight synchro pictures that benefit from an illumination
>effect similar to that of professionally used silver reflectors.
>Select a wide aperture to make your subject stand out against0
>a blurred background."
>-end quote-
>
>There is also a chart with combinations of aperture setting and
>shutter speed when there is no natural lighting using color negative
>film. With a shutter speed of 1/125 you have a working distance
>from 1m (3.3ft) to 8m (26.2ft) depending on aperture setting and
>film speed. With 1/250 from 1m to 5.6m (18.4ft), with 1/500 from
>1m to 4m (13.1ft), with 1/1000 from 1m to 2.8m (9.2ft) and with
>1/2000 from 1m to 2m (6.6ft). When there is natural lighting the
>camera-to-subject distance increases beyond the above data. Note
>that the Super FP Emission is only available when using manual
>exposure or portrait exposure mode.
>
>It is somewhat contradicting however that the Magic Lantern Guide
>talks about "this system works by pulsing the flash rapidly at
>shutter speeds faster than 1/100 of a second producing the appearance
>of flash synchronization at speeds faster than the true maximum
>sync speed", while my manual says "the super FP makes the
>duration of emission longer, achieving full synchronization
>even at faster shutter speeds". Is it not a true synchronization
>then, but merely a flash technic that produces results as if it
>was true synchronization?
Olympus super FP flash is nothing but pulsing the flash, with the
sequence of individual flashes starting before the shutter opens and
lasting until it has closed again. Whether you think the two phrases
to be contradictory is only a matter of which definition of 'true
synchronization' you use.
IMO true synchronization would ask for the flash duration to be
exactly as long as the shutter-open time. This is not feasible, in
particular with FP shutters.
So in order to prevent frames from being partly exposed one has to
choose: either the flash duration time must be completely within the
short interval during which neither of the curtains partly obscures
the film, or it must be long enough to cover the complete period
starting with the opening of the first and ending with the closing of
the second curtain.
The first is often (but mistakingly, IMHO) called true sync, the
second (being impossible in one single flash) is imitated by the burst
of very short low intensity flashes together called super FP.
>
>I guess the super FP capability of the built-in G28 flash suffers
>from weak output in much the same way as with the F280 flash.
>I wonder how the above data compares to the F280 in super FP mode?
>Wait a minute. They have the same output GN 28, doesn´t they?
>Don´t tell me it´s basically the same flash! Do the F280 have
>dual light emitting tubes as well? Maybe this is the secret
>connection between the OM and the IS system. :-)
>
No, the F-280 has a single flash tube. I think these flashes are quite
different from each other, despite their similar guide numbers.
>Frank, I sincerely hope that you´re not too disappointed
>now for having bought the IS-3 instead of the IS-3000 ;-)
>I presume you were not aware of this difference then?
Indeed I wasn't. But the IS3-DLX which I bought like new was only
$275, including date back, case, circular polfilter and skylight
filter.
The price difference with any used European IS-3000 did more than
compensate for the missing of the super FP flash....
>
>Per Nordenberg
>Kolmården, Sweden
Frank.
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