Yes, guide numbers and recyle times are very optimistic. Those with
long memories may remember the test data that I posted here for my
(then) 4 T-32's. A list member owns one of them now so I only have
three today. Here's the data I posted a year or two ago. Actual flash
output was measured with a Sekonic L-358 at both center and edge of a
28mm field of view to get a handle on vignetting. Remember that the
T-32 claims to cover 24mm. My notation: f/ 8.0.2 means f/8.0 + 0.2
stops or a shade under f/9.
Some significant points from the data:
Measured output shows guide numbers of 84 and not 104. This is not
sample variation as all 4 units tested within 1/3 stop of each other.
Output drops *very* quickly with battery voltage which drops very
quickly with even a few dozens of shots. Since NiMH and Ni-Cd are
nominally 1.2 volts instead of 1.5 volts the guide number with these
batteries is even less than my measurement of 84. Unless you're
shooting TTL or have a flash meter you may want to take these numbers
into account. There's trouble here if you're shooting slide film with
manual flash. To be quite sure, Vivitar and Sunpak lie just as much as
Olympus. I have data for Sunpaks and Vivitars too. Very similar except
that I don't have as many multiple units so I can't make the same claims
about the data not being due to sample variation.
Chuck Norcutt
-----------------------------------------------------------
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.
Tim Hughes wrote:
> No the BG2 does not boost GN since the capacitor is always charged to same
> 330V, whatever the
> source used. There is one practical exception: since the flash is fully
> charged a bit sooner on
> the BG2 ,especially after a number of flashes when using alkalines in T32,
> the GN will be higher
> than the reduced value you get when cap has not reached completely fully
> charged. Remember, when
> the flash ready light first shows, it still takes quite a bit longer for the
> cap to reach final
> charge voltage, so the GN is significantly lower than rated value for a while
> just after flash
> ready light comes on. The BG2 is likely better to get that last bit in and so
> boost GN a little in
> practical use, especially true if you have batteries in both t32 and BG2
> simultaneously.
>
> Tim Hughes
>
>>Also, I've heard claims that the BG-2 can boost the GN of flashes, has
>>anyone tested this to see if it holds water?
>>
>>Thanks,
>>Marten
>>
>>
>
>
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