In a message dated 5/4/99 9:01:16 PM Pacific Daylight Time, WKato@xxxxxxx
writes:
<< I have been struggling with OTF flash for years. Some are right on, some
are
dark, sometimes I get a full flash dump but I have a hard time figuring out
the reasons for the inconsistencies. Like Gary, the most consistent bunch
of
macro photos I have taken was when I used a totally manual dual flash set up
with a Spiratone bellows and a 80mm Janpol enlarging lens. >>
I have used macro flash (OTF) with fair success especially for slide
copying (with
Kodak slide copy Ektachrome,OM2S using a Novoflex bellows and my enlarger
lenses or Cannon (shudder!) micro lens and an adapter ring).
However,one issue not yet mentioned by all the resposes to this
thread
is that if you are not careful you can easily exceed the ability of the
camera to cut off
the flash soon enough, yielding over exposures. Higher power flashes are
usually worse
in this respect!
This is a limitation of most autoflashes whether OTF or with on flash
sensor.
If you look at the specs you will see that most flashes specify this through
some
sort of flash distance/GN minimum combination.
The solution to this problem is either to use flashes especially
setup for macro
(eg ring flashes with very low GN's ) or to add a diffuser over the flash
head or use
a ND filter. I usually tape some layers of paper towel over the flash head
and adjust
layers until I note that the recharge time of the flash becomes significant
after the
exposure indicating a reasonable amount of energy was extracted from the
flash,
and the camera is then actually managing to control the exposure. Using the
"recharge
time" only works for energy saving flashes like the T20/32 not cheaper dump
tube
flashes where the recharge time is always long as the full energy is always
dissipated.
Tim Hughes
hi100@xxxxxxx
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
|