Mike previously described his shutter testing.....
Mike,
with leaf shutters, usually the shutter open and close travel times
become a significant part of the exposure at high shutter speeds. This means
exactly where you set the light threshold of the detector circuit affects the
measured speeds. Some testers integrate the recieved light signal to get
actual light at the film plane which then takes into account travel time.
If you test your shutter with a simple tester you may find that the
shutter speed measured depends on aperture. This can be for light threshold
reasons (as above) or depending on construction because a small aperture is
obscured over a different part of leaf shutter travel. The later depends on
how close to the leaf shutter the aperture blades are. In some auto cameras
the shutter and aperture blades are one and the same.
Regards,
Tim Hughes
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