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Re: [OM] Re: XA flash shoe

Subject: Re: [OM] Re: XA flash shoe
From: rdk@xxxxxxxxx
Date: Thu, 9 Nov 2000 10:36:47 +0100


I was of the opinion that, for fill-in flash with an XA, one used the flash at
full power, where the sensor is not used, so no flash quenching takes place. The
camera sensor is a cds cell, not a Silicon Blue Cell (SBC), so I do not think
that it could react fast enough to measure light during exposure; the shutter
speed is determined at the moment you press the shutter release, not during the
exposure.
I think you have to use the flash GN (11 for A11, 16 for A16 at 100asa) to
determine the aperture, which should be about half that indicated by a normal GN
flash calculation for the required distance (i.e f11 if the calculation gives
f8).

regards
Roger Key





>I would think that it would work as follows:
>Turn on flash
>Set appropriate aperture for the flash you are using.
>Trip shutter.
>Flash fires.
>Flash quenches when enough light has reflected back to flash sensor.
>Shutter closes because camera sensor has just seen enough light (from flash) to
terminate the exposure.
>So even if the ambient light required an exposure of 5 sec., the exposure
actually ends when the flash is quenched.  >(not considering various electonic &
mechanical delays inherent in the system).
>What do you think ?
>...Wayne


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