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[OM] Coverage angle of T-32, was: Vivitar 550FD M/P/O discussion

Subject: [OM] Coverage angle of T-32, was: Vivitar 550FD M/P/O discussion
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxx>
Date: Thu, 06 Jan 2005 11:48:30 -0500
Tim said:
Wayne which publication says the T32 covers 28mm only?
The esif is pretty clear:
http://olympus.dementia.org/eSIF/om-sif/flashphotogroup/t32.htm
I seem to remember using my flashmeter to check that it is pretty wide?
This was always an important feature for me, since I use 24mm a lot.
Although I typically add diffuser/bounce to most flashes now to reduce 
harshness.
-----------------------------------
I suppose the actual coverage depends upon your standards for 
illumination.  Some months ago I was testing single and multiple T-32's 
against a Lumedyne flash head with a 50/100/200 watt second power pack 
with my flash meter.

A single T-32 almost exactly matches the Lumedyne in total power output 
when the Lumedyne is set to 100 watt seconds.  It also matches the 
Lumedyne coverage angle. Both flashes fall off approximately 1/2 stop 
horizontally at the edge of the field of a 28mm lens at a distance of 10 
feet.  I didn't measure out to 24mm but guess it must be about 1 stop.

As to the prior Vivitar 550FD discussion, I have two of these and tend 
to use them in a hotshoe with a T-32 in the BG-2.  I bounce the T-32 to 
  light the room and side of the subject and use the 550FD straight on. 
  The 550FD's are very nice little flashes and, as Wayne can attest, can 
be had very cheaply.  However, there is no real comparison to a T-32. 
The power output of a 550FD is quite small in comparison.  The 550FD's 
guide number of 24 is for coverage with a 50mm lens.  The T-32's is 32 
for a 24mm lens.  Since a 24mm lens covers 4 times the area of a 50mm 
lens, if my calculations are correct, it would take about 7 550FD's to 
produce the same amount of light as a T-32.

Chuck Norcutt


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