Far be it from me to argue with John Shaw but I didn't understand your
comment about correction for non-mid-toned subjects. It's my impression
you are talking about the use of guide numbers there. If the guide
numbers are accurate they are controlling for the amount of light
falling on the subject. In essence, the same as an incident light
reading which should not need to be adjusted for subject reflectance.
Dr. Flash
On 9/13/2010 7:50 PM, usher99@xxxxxxx wrote:
> 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. "
--
_________________________________________________________________
Options: http://lists.thomasclausen.net/mailman/listinfo/olympus
Archives: http://lists.thomasclausen.net/mailman/private/olympus/
Themed Olympus Photo Exhibition: http://www.tope.nl/
|