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Sv: [OM] F280, Risk Homeostasis, Salty OM4s, and S*U*Vs

Subject: Sv: [OM] F280, Risk Homeostasis, Salty OM4s, and S*U*Vs
From: "LARS BUNDESEN" <lars.bundesen@xxxxxxxxxx>
Date: Wed, 22 Sep 1999 20:04:47 +0200
Thanks for the responses about the OM 3 Ti and 280.

It seems I'll have to go for an EOS 3 and not a OM 3 Ti, if I want better
flash facilities. Well, 90 0f the time, I don't need anything more than
what my OMs deliver, so I won't change.

Lars


----------
> Fra: WKato@xxxxxxx
> Til: olympus@xxxxxxxxxxxxxxx
> Emne: Re: [OM] F280, Risk Homeostasis, Salty OM4s, and S*U*Vs
> Dato: 22. september 1999 17:22
> 
> In a message dated 99-09-22 06:38:45 EDT, you, Hans, write:
> 
> >>>  In manual mode the OM-4Ti uses the F280 exactly like the  OM-3Ti:
the 
> flash is synchronized at all shutter speeds from 1 sec to 1/2000  sec,
and 
> your exposure calculations must be GN based, where the GN depends on the 
> selected shutter speed. <<< 
> 
> I thought GNs were based on aperture setting but I suppose the F280 is
just 
> like using a photoflood where you can adjust the shutter speed, aperture
and 
> distance to effect the final exposure.  This three variable system along
with 
> light from ambient light has my head spinning.  The good news here is
that I 
> don't have to buy an OM3Ti if they both work the same in manual.
> 
> >>>Biggest problem in this mode, which obviously is the only mode the
OM-3Ti 
> can handle, is that available light is not taken into account and 
> overexposure can easily happen when there is a lot of it. So to  answer
the 
> original question: nothing is calculated automatically, _you_  must do
the 
> calculations just as with ordinary manual (fill)flash. Biggest difference
is 
> that you can select from six different GN's (2.6, 3.7, 5.2, 7.3, 10.4 and

> 14.7m, 100ASA), depending on the shutter speed used and you no longer are

> limited  by a sync shutter speed.<<<
> 
> I thought the GN was 28 but am I thinking too simply? What shutter speeds
to 
> these GNs compare to?  I think I need to book (someone can write it I
guess) 
> called "OM4T and OM3T Fill Flash for Dummies."   
> 
> >>>The OM-4Ti in Auto mode treats the F280 in FP mode just like an
additional 
> light source, measures the total light Off The Curtain and determines the

> final shutter speed during exposure, so overexposure is much less likely.
<<<
> 
> This I never did understand totally. So I take it that the OM4T first
takes a 
> reflected light averaging reading, spot reading or spot averaging
reading, 
> then FP flash fires on the closed shutter curtain to determine the
shutter 
> speed, adds it to the previously reflected light reading, and then
calculates 
> the shutter speed according to some internal formula that nobody knows?? 

> Also why does the Manual B for OM4t say that Super FP duration is 20 to
40 
> milliseconds? What does this variable depend on?
> 
> >>>When the indicated shutter speed is longer than 1/60 and you leave the

> camera to Auto, despite what the manual says, the shutter speed is fixed
at 
> 1/60, but the flash remains in FP mode, not regular TTL flash (you can
note 
> the difference by watching the charging time), and the exposure will
probably 
> be wrong.<<<
> 
> As to salty OM4s and S*U*Vs, my OM homeostasis factor is feeling a little

> uncomfortable.
> 
> Warren
> --Trying to stay 3 SD out from the mean in the bell curve
> 
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