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Re: [OM] T32 Auto setting inaccurate

Subject: Re: [OM] T32 Auto setting inaccurate
From: HI100@xxxxxxx
Date: Wed, 5 May 1999 03:19:55 EDT
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

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