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[OM] Re: Something I hate to admit in public...

Subject: [OM] Re: Something I hate to admit in public...
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
Date: Sun, 04 Feb 2007 22:50:38 -0500
I used to own four T-32's (now down to three) but when I had all four I 
did measure them with the meter and found them to all be within 1/3 stop 
of each other.  I think I've posted this before but you can read the 
data and find the answers to these and other questions.  Note the 
difference in power output with recycle time (beyond the ready light) 
and with battery voltage (including NiMH 1.2v vs Alkaline 1.55v)
(the notation f/8.0.2 means f/8.0 + 2/10 stop)
------------------------------------------------------------

T-32 flash power and recharge test

@ 10 feet, ISO 100, no diffuser, max power
                Center          Edge of 28mm field of view
1 unit  =       f/ 8.0.2                f/ 5.6.8
2 units =       f/11.0.1                f/ 8.0.6
4 units =       f/ 16.0.1               f/ 11.0.7

@ 10 feet, ISO 100, small umbrella, max power
                Center          Edge
1 unit  =       f/ 4.0.0                f/ 2.8.6
2 units =       f/ 4.0.9                f/ 4.0.5
4 units =       f/ 8.0.1                f/ 5.6.7

@ 10 feet, ISO 100, no diffuser, at 1/4 power
                Center          Edge
4 units =       f/ 4.0.2                f/ 2.8.7

Note:  All 4 units test within 1/3 stop of each other.  Output is very 
sensitive to battery voltage.  AA alkalines produce about 1/3 stop less 
output after 20-30 flashes.

Output with alkaline AA’s at 1.54 volts = f/ 8.0.4, at 1.33 volts = 
5.6.9.  Actual measured guide number with fresh alkalines is only 84 vs. 
spec of 104.

  5.6.9 is the max observed power output using 1800mah NiMH batteries or 
0.5 stops below max with alkaline.

A single T-32 is approx. 100 watt seconds compared to Lumedyne at 100 w/s

Recycle times with 1800mah NiMH batteries.  Power measured at 10 ft.:
Time            Power, f/stop
   5 sec                f/ 4.0.9
7.5 sec f/ 5.6.3
10 sec          f/ 5.6.6
15 sec          f/ 5.6.7
20 sec          f/ 5.6.8

Note:  Max of f/5.6.9 observed for NiMH batteries still not achieved in 
20 seconds.
-----------------------------------------------------

Chuck Norcutt



> 
> 
> I like it.  Do flashe guide numbers vary between examples of the same flash. 
> I 
> know that battery charge influences ecycle time, but I assume that unless the 
> are almost dead they don't change the guide number.

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