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Re: [OM] fill flash - am I missing something?

Subject: Re: [OM] fill flash - am I missing something?
From: "John Hudson" <13874@xxxxxxxxxx>
Date: Mon, 4 Nov 2002 22:23:33 -0400
----- Original Message -----
From: "Wayne Culberson" <waynecul@xxxxxxxxxxxxxxx>
To: <olympus@xxxxxxxxxxxxxxx>
Sent: Monday, 04 November, 2002 09:35 PM
Subject: Re: [OM] fill flash - am I missing something?


>
> ----- Original Message -----
> From: Tim Chakravorty
> > The problem with the OMs (except 3Ti/4Ti) is that for ttl auto, they
sync
> at 1/60 and *only* at 1/60. Period.
>
>
>
> Thanks, Tim. Seems like the book should make it that simple.
>
> Another question then, if the flash sync speed is 1/60 ttl, why does Carl
> Shipman in his book say to "set shutter speed to1/30 or slower" when using
> manual operation or normal auto operation (page 97, 98, 10th edition)? Is
he
> just trying to be extra careful? Is there some circumstance where they
don't
> sync at 1/60 manual and 1/60 mechanical?
> Wayne

Wayne ... what I think Shipman is saying by setting the shutter speed to
1/30 or slower is to allow for more ambient light to reach the film. By
using the sync speed at whatever aperture is necessary [ie: guide number @
100 ISO divided by flash to subject distance] the flash will be the only or
the dominant source of light excluding the effect of any ambient light. By
slowing down the shutter speed below sync speed and holding the aperture
constant the image will be illluminated by more ambient light than would
otherwise be the case. Where the exposure on camera for the ambient light
only is made to exactly match what the flash exposure would be exclusive of
any ambient light effect the intensity of the flash exposure for the flash
to subject distance will exactly balance the ambient light effect. As the
intensity of the flash exposure is increased you are effectively crowding
out the ambient light effect until you reach the point where the ambient
light no longer is recorded on the film. By playing off the flash exposure
against the ambient light you can effectively increase or decrease the
illumination of the background and / or help illuminate any shadow areas on
the subject that are inadequately illuminated by the ambient light.

John H





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