Jan,
No the frequency is nominally fixed at ~20kHz, although in reality it is
made to vary as the
capacitor discharges to give more pulses near the end to compensate for the
fact each succesive
pulse is at a lower voltage, and this keeps illumination even over shutter
travel. The
compensation is an anlog circuit, that is adjusted at factory and gives a
unique profile of pulses
dependent on the particular tube characteristic.
Tim Hughes
--- Jan Steinman <Jan@xxxxxxxxxxxxxx> wrote:
>
> > From: Tim Hughes <timhughes@xxxxxxxx>
> >
> > Yes the f280 is exactly like an incandescent light...
>
> Except it's actually a very fast sequence of pulses, no?
>
> It's been years since I looked into it, but I owned an F-280 once, and
> it was my understanding that it actually did auto-exposure based upon
> changing the pulse frequency, and thus, the duty cycle, which then
> changed the actual light output over time.
>
> At least, that's how *I* would design such a thing. Was this my own
> hare-brained idea, or not? :-)
>
> :::: At any given moment, there is a sort of all-pervading orthodoxy,
> a general tacit agreement not to discuss large and uncomfortable
> facts. - George Orwell ::::
> :::: Jan Steinman http://www.EcoReality.org ::::
>
>
>
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