1/24/02 4:39:00 PM, "John A. Lind" <jlind@xxxxxxxxxxxx> wrote:
>Acer,
>The clues:
>(1) One T-32 with a diffuser effectively making it about the same as a
>T-20 without one.
right, effective GN was ~23
>(2) Fuji NPS (not a bad film choice; the film speed is the key).
haha!
>(3) Lens aperture set to f/8.
Well, i looked at the flash calc panel before i went out to get film, and this
is what i figured:
1) diffuser would lose me no more than 2/3 stop (measured light w/ gossen light
meter--regular, not flash--
with and w/o diffuser pointing to the sky). round it to 1stop even, giving a
slight overexposure for safety
margin
2) so instead of 160, figure effective filmspeed for GN calcs as 80
3) with T32 calc panel set to ISO80, 12ft range gives me f/8 normal auto,
decent DOF
with those three points, i figured i'd be OK....
but i guess not!
>See my "wedding" tutorial about the need for flash power (scroll down to
>the tables of film speeds, apertures, distances and flash GN ratings [given
>for ISO 100]):
> http://johnlind.tripod.com/wedding/rightstuff.html#equipment
> <http://johnlind.tripod.com/wedding/planning.html#Exposure and
>Lighting>http://johnlind.tripod.com/wedding/planning.html#Exposure and Lighting
ah yes, i'd read that when you first wrote it. i suppose a refresher is in
order.
>I suspect you simply did not have enough flash power. I must watch
>carefully when using Kodachrome 64 indoors that I keep aperture to f/4 or
>f/5.6 lest I run out of flash power with a single T-32. If this was a
>"reception" held in a reception hall or banquet room, distances are
>deceptively farther than inside someone's living room! This is one of the
>reasons the pros use very, very powerful flash heads for "event"
>shooting. It allows stopping the aperture down to f/8 and still being able
>to throw enough diffused light over 20 feet to properly expose ISO 100 or
>ISO 160 film.
and then there's no stray "bounce off the side walls or ceiling" light to
augument the subject! further
lowering the GN (which i know manufacturers report for indoors to get a few
more feet range)
>A T-32 with the 21mm WA diffuser is effectively a T-20. At f/8 you only
>have enough flash power for a maximum distance of about 8-10 feet. You
>need to run something more powerful than a single T-32. This is something
>I suspected and confirmed during my first wedding shoot as an "apprentice"
>with a local pro. You need a GN of about 150-160 [ISO 100 in feet],
>*after* taking into account any diffusion or bounce device you use. It's
>the reason I used a pair of T-32's on a bracket without diffusers!
I guess I might have to do direct T32, no diffuser, or step up to NPH. I like
the no diffuser part better, so i
can shoot closer scenes w/o stopping down too much.
>If you decide to shoot the wedding for them, start at the beginning:
> http://johnlind.tripod.com/wedding/
oh no! I'm just doing this on the side cuz I can and want to!
>-- John
>[who doesn't claim to be a great wedding photographer; just one who
>understands many of the technical issues associated with it]
...and many other technical (and philosophical too <gg>) issues :) great to
have made your acquaintance!
/A/S
--
dum spiro, spero
http://users2.ev1.net/~wesiddiquis/siddiq/
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