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08-19-2010, 12:30 AM   #1
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AF280T Flash - Need to compensate for ceiling bounce in TTL?

Sorry in advance if this is a newbie question...

When using the AF280T in TTL on a TTL-enabled camera (mine include: LX, PZ-1, MZ-5n, *ist DS), is the TTL flash supposed to automatically compensate for light loss due to bouncing? Or do I need to manually bump up flash comp?

I'm asking this as sometimes I get somewhat erratic results on the *ist DS. I find I need a flash comp of +0.7 for closer shots, and it still underexposes at +1.0 for more distant subjects. I haven't tried the flash on any of my film cameras yet.

Thanks in advance.

08-19-2010, 01:41 AM   #2
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QuoteOriginally posted by iht Quote
Sorry in advance if this is a newbie question...

When using the AF280T in TTL on a TTL-enabled camera (mine include: LX, PZ-1, MZ-5n, *ist DS), is the TTL flash supposed to automatically compensate for light loss due to bouncing? Or do I need to manually bump up flash comp?

I'm asking this as sometimes I get somewhat erratic results on the *ist DS. I find I need a flash comp of +0.7 for closer shots, and it still underexposes at +1.0 for more distant subjects. I haven't tried the flash on any of my film cameras yet.

Thanks in advance.
I used to own one of these, which I used with a Super A & an LX, & I never made any adjustments at all.
So, my answer would be, in normal circumstances, NO.....but if you were operating in a large area at extreme flash range etc, then maybe you would have to.
Cheers, Pickles.
08-19-2010, 05:13 AM   #3
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QuoteQuote:
but if you were operating in a large area at extreme flash range etc,
Thanks Pickles. Maybe I'll try it on my MZ-5n or PZ-1. Hmm...would 10-20m considered to be in the "extremely flash range"?

Having said all that, it's really quite a nifty flash unit.
08-19-2010, 05:35 AM   #4
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QuoteOriginally posted by iht Quote
Thanks Pickles. Maybe I'll try it on my MZ-5n or PZ-1. Hmm...would 10-20m considered to be in the "extremely flash range"?
Yes. The flash has a guide number of 28, so at f/2.8, 10 meters is the extent of its effective direct reach. If you're bouncing, that makes the distance even more not only to you have to get to the ceiling and back down, but some of the flash is absorbed and some is reflected in non-useful directions.

08-19-2010, 05:37 AM   #5
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Yes. The flash has a guide number of 28, so at f/2.8, 10 meters is the extent of its effective direct reach. If you're bouncing, that makes the distance even more — not only to you have to get to the ceiling and back down, but some of the flash is absorbed and some is reflected in non-useful directions.
Btw, I neglected to mention I shoot in ISO400. I remember reading somewhere that 400 is the "optimum" speed, but can't remember why. Should this make a difference?
08-19-2010, 03:51 PM   #6
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QuoteOriginally posted by iht Quote
Btw, I neglected to mention I shoot in ISO400. I remember reading somewhere that 400 is the "optimum" speed, but can't remember why. Should this make a difference?
If you're shooting at 400, then I'd say that would give you even more range, as guide numbers are calculated at 100 are they not. I used to have one of these, & they are indeed a "nifty" unit, perhaps a little "outgunned" by later units, but still a good solid little flash all the same...you can get tele & wide angle "converters" for them too.
Can't remember what the back of the unit looks like, but from memory, there are various "scales" etc there, which I think would show that when you change the ASA from 100 to 400, flash range would increase dramatically.
Cheers, Pickles.
08-19-2010, 06:58 PM   #7
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QuoteOriginally posted by iht Quote
Btw, I neglected to mention I shoot in ISO400. I remember reading somewhere that 400 is the "optimum" speed, but can't remember why. Should this make a difference?
This progresses along the same sqrt(2) pattern as aperture numbers. Each doubling of ISO multiplies the guide number by sqrt(2). Or to think of it more easily, each two stops up in ISO doubles distance the flash covers.

ISO 400 is probably selected as "optimum" because 1) it's low enough that noise is still well controlled 2) it gives you a nice relative increase in flash power, and 3) it's easy to calculate doubled numbers.

I use ISO 400 too, because I find it gives me enough power with my Metz 48 AF1 to comfortably use f/8 with bounced flash indoors.
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