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Re: [OM] Golden Child Kit first time outing

Subject: Re: [OM] Golden Child Kit first time outing
From: Ken Norton <ken@xxxxxxxxxxx>
Date: Thu, 12 Mar 2009 11:58:39 -0500
>OK, but it doesn't take an OM-3Ti and T45 to do that.  The beauty of it is
>the constant aperture setting, yes?  On the OM-2S, a + or - exp comp
>changes the aperture, doesn't it?

>
Well, yes and no.  The exposure compensation dial is really only adjusting
the ISO setting. When you are in full-auto mode with the 2S or 4T, if you
are starting at ISO 400 and adjust the exposure compensation dial to +1.0,
you've actually turned the internal ISO selector to ISO 200.  That's why, on
the OM bodies, the rings are co-located.

The TTL flash works in TTL mode only in Auto on the 2S and 4(Ti). As such,
if you dial in -2/3 exposure compensation it is not only "dimming" the flash
by 2/3 a stop, but it is also altering the entire exposure accordingly--ie.,
the ambient exposure. This is why you cannot effectively adjust fill-factors
with the OM system.

To the best of my knowledge, neither the OM-2(md,n,s) or OM-4(T,Ti) will
operate the flash in TTL while in manual-exposure mode.  The OM-3Ti allows
me to dial in a fixed shutter speed up to 1/60 second and any aperture. If I
want to keep my flash from blasting the snot out of someone's face, I can
use exposure compensation to weaken the flash, but my ambient exposure
remains fixed.

That said,...

I did extensive testing with the OM-2S/T45 and this camera seems to work
better than the OM-4T in the following scenario--not that the 4T is a dog,
but the 2S seems to have a slightly different set of rules in the
algorithm:  When shooting in Auto exposure mode with TTL flash, you adjust
the aperture till the indicated shutter speed is no faster than 1/60.  Any
faster and the flash will not fire. The 2S forces the shutter speed DURING
exposure to 1/60, but the scale will show the required exposure for the
ambient lighting.  As a general rule of thumb, I always try to keep the
scale showing between 1/8 and 1/30.  At 1/15, this puts the ambient exposure
two stops down which seems to be about the perfect ratio for me.
Unfortunately, this means that I cannot use the TTL flash-control for
fill-flash as the ambient exposure is showing at 1/60 or faster and the
flash will fail to fire.  I honestly haven't spent enough time with the 4T
in this scenario to determine exactly how, in predictable terms, how it
works in comparison to the OM-2S but it seems to fire the flash if the
ambient exposure is showing 1/60 whereas tthe OM-2S doesn't.

So, for outdoor fill flash where my background is notably brighter than the
foreground, it is not possible to use TTL flash as the flash will not fire.
But that's where the OM-3Ti is different.  The OM-3Ti will fire the flash no
matter what. So, I can go ahead and adjust my aperture (shutter speed is
generally fixed) for the background, placing it high-key and using the TTL
flash to fill the faces.  However, to keep from getting that over-flash
look, I would adjust the exposure-compensation dial down, say -2/3 to fill
the shadows but not get the flat look.


>It would take balls if you were shooting on transparency film!

I'm not that much of a man.

AG
-- 
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