Kennedy wrote:
>
> 1/250,000th, or 4uS, is an age in electronics - your PC could probably
> calculate pi to quite a few places in that time if programmed
> appropriately, so I don't buy that one.
>
That depends. When you are only handling information, as in a PC, things
can go very fast. When dealing with significant power levels, things are
not so simple, just ask any designer of switch mode power supplys. An
electronic flash has a high current running through the flash tube. This
not something you just turn off, even with modern electronics.
Incidently, one of the main reasons for the high speed of modern computers
is the very low power level they work at.
> Afterglow? Its a long time since I did any plasma physics, but I think
> the time for the spark to decay once the energy source has been removed
> (via the thyristor in the flash circuit) is of the order of pico-
> seconds.
>
Maybe, it's been some years since I last had any datasheets on flash
tubes handy, so I don't have any hard information on this. But to get
all the exited atoms back to their normal state in picoseconds? I'm
sceptical.
Anyway, we need hard facts for this to make sense. Physics is very
interesting, but does not improve the pictures beyond a certain point.
Computer flash works, that's the most important part.
> My guess is that the times at which reciprocity starts to reappear are
> closer to 1uS mark or less, rather than any failing of the circuit to
> control the flash fast enough. Of course reciprocity failure might just
> have a slower fall off at the high speed end than it has at the long
> time period - the mechanisms are probably completely different - so its
> a bit less noticeable.
> --
> Kennedy
> Yes, Socrates himself is particularly missed;
> A lovely little thinker, but a bugger when he's pissed.
> Python Philosophers (replace 'nospam' with 'kennedym' when replying)
>
Regards
Lars
--
Lars Haven <mailto:lhaven@xxxxxxxxxxxxx> aka <lhaven@xxxxxxxxxxxx>
"When writing about women, one must dip one's pen in a rainbow"
D. Diderot
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