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Re: [OM] Re: XA flash shoe

Subject: Re: [OM] Re: XA flash shoe
From: Andrew Fildes <afildes@xxxxxxxxxxxxxx>
Date: Fri, 10 Nov 2000 19:42:13 +1100
It is also possible to use a piece of diffuser material or a piece of ND
filter, such as a a beat-up old Cokin, to reduce flash output to half or a
quarter, for better fill-flash results - with an aperture of choice.
Andrew


>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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