Archived posting to the Leica Users Group, 2004/03/03

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Subject: [Leica] Re: Ambient light + Strobe metering question
From: "Eric" <ericm@pobox.com>
Date: Wed, 03 Mar 2004 17:43:13 -0600
References: <BAY10-DAV23ozjo5QHH00014880@hotmail.com>

Eric:

> A photo technique book I was reading has a chapter on using a strobe
> for fill light.  As an example, the author discussing an ambient lit
> scene which meters f 5.6 at 1/125 sec He then discusses the use of a
> strobe set to output of 5.6 and varying the shutter speed to add or
> subtract ambient light.

That doesn't sound like he's using flash for fill.  If the ambient light
exposure is 5.6 at 1/125, then it's not like you can add ambient light and
expose 5.6 at 1/60.  Your picture will be overexposed.

If you want just a fill light, I'd suggest setting the flash for 2.8.  Two
stops over 5.6.  If you had no ambient light at all, your picture would be
two stops underexposed.  The flash is letting off just enough light for a
perfect exposure at 2.8.  But by shooting at 5.6, you're only letting in 1/4
of that light.  Go ahead and shoot at the indicated shutter speed of 1/125.
You'll be overexposing your image by a slight amount.  Less when you get
good at directing the flash just to fill in the shadows.

If you want the flash to dominate, then set your flash to 5.6.  With a
shutter speed of 1/125, you'll get 1:1 between ambient and flash, and you'll
be a stop overexposed.  Change your shutter speed to 1/500, and you'll have
just the opposite of above.  Flash will be at a normal exposure, and ambient
will be a fill light.

If you want a 1:1 balance, then set your flash to f4, and shoot 5.6 at
1/250.  That gives half the "correct" exposure to the flash and half to
ambient.

>When shooting outdoors and metering a scene (ambient light + strobe), how do
>I isolate the f stop output of the strobe?

When you're talking about metering, how are you metering?  With a hand held,
incident flash meter?  In that case, you don't have to worry about the
ambinet light.  Without a flash meter, use the flash number and a tape
measure.

And now just take the dang twinkie light off, throw it in the nearest river,
and bask in the glory of available light that your Leica can help you
capture.  :)


Eric
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Replies: Reply from "eric" <leica_korenman@hotmail.com> (Re: [Leica] Re: Ambient light + Strobe metering question)
In reply to: Message from "eric" <leica_korenman@hotmail.com> ([Leica] Ambient light + Strobe metering question)