The only reason to be concerned about the distance for the flash units
is the minimum distance requirement in auto mode. But since they're
having difficulty delivering as much light as you'd like in auto mode
just put them in manual mode so that they're firing at full power all
the time. Then adjust the light on the subject side of the diffuser but
moving the flashes toward or away from the diffuser. In manual mode it
won't matter how close or far they are since there's no timing
requirement to quench the flash.
Since your diffusers are much taller than they are wide I'd suggest
turning the flash units to portrait orientation if the tripods will do
that. Then the shape of the flash head and angular light pattern will
be a better fit to the shape of the diffusers. It should deliver a bit
more light and a bit more even.
The ISO 25 f/4 instruction just happens to work out on the T20 which is
good since my instructions were actually using the markings on the T32. :-)
Chuck Norcutt
On 10/3/2010 12:33 PM, Olaf Greve wrote:
> Hi Chuck,
>
> Alright, a major snip of your long, excellent, explanation.
>
> Some first results:
>
> As for the settings: I set the T20s to manual, ISO 25, f4, just like
> you said. The camera was now set to manual, 1/160th speed, and the
> aperture and flash distances were adjusted, so as to get something
> workable. The ISO setting was set to 100.
>
> Shooting at about half a meter through the canvas, gave too little
> light throughput, even when the aperture was all the way open at f5.6.
> Moving the flashes closer (at some 20 centimetres) gave far better
> results, especially at f5.6.
>
> I then tried something else as a diffuser: a 'room separator' that's
> made of light tanned cloths. Due to the folding mechanism, the set-up
> had to be changed, and this time the flashes were set at a 45 degrees
> angle from the front of the round. The results are very similar to
> those of the canvas-diffuser-shots. Possibly the more powerful flashes
> (i.e. T32 + T28 Twin) need to be used, or I might be better off using
> thinner diffuser material.
>
> I'm thinking of giving the cloth-design-tracing paper a go. That would
> allow me to set the flashes further away, hopefully eliminating all
> shadows (in the current test of some light shadows are still visible).
>
> Some sample pictures (note that in none of these the WB was set
> customly, so these should just be observed as examples of what the set-
> up more or less does):
>
> 1) http://www.millennics.com/test/PA035697.JPG
> E-500 + 14-45 F3.5-5.6, Manual, 1/160 @ f5.6, ISO 100, two T20s, one
> to the left, one to the right of the subject, both firing through
> canvas diffusers, distance from flash to diffuser +/- 20 cm, distance
> of diffuser to subject +/- 25 cm.
>
> 2) http://www.millennics.com/test/PA035703.JPG
> E-500 + 14-45 F3.5-5.6, Manual, 1/160 @ f5.6, ISO 100, two T20s, set-
> up at a 45 angle degree from the front of the subject, both firing
> through cloth diffusers, distance from flash to diffuser +/- 25 cm,
> distance of diffuser to subject +/- 25 cm.
>
> Then some pictures of the second set-up:
>
> http://www.millennics.com/test/PA035704S.JPG
> http://www.millennics.com/test/PA035705S.JPG
> http://www.millennics.com/test/PA035706S.jpg (note the lower case
> extension!)
> http://www.millennics.com/test/PA035707S.JPG
>
> Well then, so much for the first trials...
>
> I very much welcome further comments and tips. :P
>
> Next up: trying thinner diffusing material and setting the flashes a
> bit higher (hopefully eliminating the slightly darker 'bar' on the top
> of the round)...
>
> Cheers,
> Olafo
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