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Re: [OM] Shutter Tapering

Subject: Re: [OM] Shutter Tapering
From: HI100@xxxxxxx
Date: Mon, 16 Apr 2001 04:52:20 EDT
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
                >>Hi100@xxxxxxx<<

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