This is fascinating because it's pretty much how I was planning on setting up a
shutter speed tester at home. The main difference is that I was planning on
using an infrared LED emitter/detector pair (driven by an oscillator) and a
frequency counter set up as a manually reset event counter. Think this would
work?
Mark Roberts
P.S. I'll bet the K2 shutter speeds that were off were too *long* as opposed to
too short.
"David A. Mann" <[EMAIL PROTECTED]> wrote:
> Basically all I did was shine a low-power laser into the shutter, with a small
>silicon photocell on the other side, so the photocell gets lit up while the shutter
>is open.
>
> Attached to the photocell was a digital oscilloscope in single-shot mode,
>triggering off the rising edge. The 'scope has an automatic pulse-width
>measurement so I just used that to measure how long the shutter was open.
>The 10mW laser gave me about 400mV (or 0.4V for the non-metric) out of the
>photocell so I had plenty of signal to work with.
>
> It worked well until the really high shutter speeds (above 1/1000 on the Z-1p)
>where a combination of the speed of the silicon cell and the width of the slit
>relative to the beam caused inaccuracies. That's my theory, anyway.
>
> All the rest of the work (converting all the info into "X stops over/under") was
>done using a spreadsheet.
>
>Cheers,
>
>
>- Dave
>
>David A. Mann, B.E. (Elec)
>http://www.digistar.com/~dmann/
>
>"Why is it that if an adult behaves like a child they lock him up,
> while children are allowed to run free on the streets?" -- Garfield
>-
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