Kinda late here, but one other method I think deserves mention. I
believe the GN are reasonably accurate and are the basis for the
calculator
panels that are available. The GN for the T28 dual is 28 (duh) with
one light used and 22 with both--long thread on that last year or
so--they are in series. There is an adjustment as well IIRC. Macro
flash GN is less dependent
on conditions as it is so close to the subject and I know the T32 as
measured by Dr. Flash does fall off from the center a bit more than I
had appreciated. This precludes use of modifiers unless the effect is
known. The calculator panels presumed the GN is accurate and
incorporate light lost due to extension and subject distance last time
I checked. Correction for non-mid-toned subject is opposite direction
than that used for auto or TTL per John Shaw. This works (at least
within the exposure latitude of the film I was using at the time) and
isn't as fussy as it sounds. I wish the TTL flash had a spot metering
mode--not sure any such beast exists anywhere. Auto mode is often
horrifically fooled by the background given what it monitors. I think
Tim had mentioned there is an old Viv flash that had an auxiliary spot
auto monitor that would be cool for macro.
An Occasional manual macro flash mode, Mike
"For my writing project, I am doing close-ups of plant parts.
Some of these (I might post examples) are likely to be fairly small and
with a
black velvet background.
Other authors have used this technique to good effect.
If I were to use flash, I think I can foresee big problems ahead as an
auto
unit tries to illuminate the dark background.
Brian Swale. "
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