At 08:52 PM 9/21/00 +0800, you wrote:
>Paul,
>
>Totally agree with your idea, but... I just tried again at 10 feet distance,
>my two T32s only gave me F5.6 +0.5 EV. My room has white ceiling and very
>light color wall, seems the reflection is not so effective. Tried again at
>1m distance, the reading is F16 +0.4 EV. In both cases still have around
>1.5 stop under.... I started to think that my flash meter might have some
>problem. Does anyone have a flash meter want to join the test?
>
>P.S. I use a lumisphere for incident measurement, I think it should be the
>right way. On the other hand I found using fresh alkaline batteries with
>longer charging time, the power is 0.2-0.3 stops higher than using Ni-cd,
>may be due to higher battery voltage.
>
>C.H.Ling
I got a chance to test again this evening.
T-32, AC adapter, Minolta Autometer IIIf with hemisphere receptor
Room about 12' * 14', shooting across short dimension near middle,
walls lt blue on lower 1/3, white above, white 9' ceiling, light vinyl
floor, dark furniture. Lights dimmed very low.
Flash and meter about 4 1/2' up.
There were a couple of minutes between flashes, so the capacitors should
have been fully charged.
At 3m, f/8 + 8/10: GN=32
at 2m, f/11 + 7/10: GN=28
at 1m, f/22 + 6/10: GN=27
You can see that at 3m I start getting ceiling and floor bounce. I don't get
anywhere near the 1.5 stop loss you see. I got about the same result earlier
with alkalines.
I still have spots in my vision from full power shots in a dark room. (I was
behind the flash, pinting it at the meter.)
Paul
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