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From: hofbauer@utcsri.UUCP (John Hofbauer)
Newsgroups: net.rec.photo
Subject: Re: Zooming during an exposure.
Message-ID: <2292@utcsri.UUCP>
Date: Fri, 7-Mar-86 22:58:49 EST
Article-I.D.: utcsri.2292
Posted: Fri Mar  7 22:58:49 1986
Date-Received: Sat, 8-Mar-86 00:48:04 EST
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Organization: CSRI, University of Toronto
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> 
> and the camera is a Nikon FE2. I am planning to zoom during an exposure  
> at dusk, with the camera set on automatic (aperture priority) mode. 
>   
>   During the zoom the effective aperture of this lens changes. My question
> is if the automatic exposure system will respond to this change by adjusting 
> the shutter speed DURING THE EXPOSURE - the shutter has already been released
> and the exposure is in progress when the aperture changes because of the
> effect of zooming with this lens. Does the metering system select a shutter
> speed at the instant  the shutter release is depressed and "freeze" it for the
> duration of the exposure ? Or does the system respond to changes during the
> exposure ?
> 
>   I am concerned about this because I expect the exposure to be fairly long.
> If the exposure was short, a decrease in aperture during the exposure would
> probably not have any significant effect. For all I know, there may be no

The meter cell of the FE2 is located in the viewfinder area, so
no light will reach it during exposure because the mirror is in
the up position. Therefore the exposure must be determined before
the shutter is released. A shift of aperture during a long exposure
is less critical than during a short exposure. Reciprocity failure
makes just as much difference. Forget about the technical details,
just do it, and bracket liberally. Zooming during exposure produces
wonderful results. I've had great success with it. One was published
on the cover of a local magazine who paid me handsomely for it.