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From: beyer@houxs.ATT.COM (J.BEYER)
Newsgroups: sci.electronics,rec.photo
Subject: Re: Flashbulbs
Summary: With electronic flash, exposure is controlled by aperture and distance.
Message-ID: <1143@houxs.ATT.COM>
Date: 23 Jan 89 13:31:53 GMT
References: <9844@sequent.UUCP> <1818@maccs.McMaster.CA>
Organization: AT&T BL Holmdel NJ USA
Lines: 29

In article <1818@maccs.McMaster.CA>, nusip@maccs.McMaster.CA (Mike Borza) writes:
> In article <9844@sequent.UUCP> brian@crg1.UUCP (Brian Godfrey) writes:
> >   Electronic flash is extremely fast, ranging generally from 1/5000 to
> >1/25000. With electronic flash you have to make sure and wait until the
> >shutter is all the way open before triggering the flash. This takes from
> >1/250 sec on some cameras to 1/60 sec on others. The actual exposure 
> >happens very quickly. Then the shutter closes at its leisurely pace.
>
My electronic flash units last 1/300 second at maximum power.
 
> Pardon my ignorance, but... doesn't this mean that shutter speed is
> essentially irrelevant for a flash picture taken using an electronic
> flash?  If so, how does one control the exposure?

Shutter speed, in a dark room does not matter when taking electronic flash
pictures. In a lighted room, or outdoors, if the shutter is open long enough,
the available light will also participate in making the image, and many
techniques may be used for special effects.

In those cases where the electronic flash unit provides most of the light,
the exposure is determined by the light output of the flash and the aperture
of the lens.



-- 
Jean-David Beyer
A.T.&T., Holmdel, New Jersey, 07733
houxs!beyer