Not clear quite what you mean by your questions Simon - let's try this way:
In Normal Auto mode, T-series flashguns use their own light sensor to
measure the reflected light from the scene, and in conjunction with the film
speed you have set on the flashgun, they quench the flash when they judge
there is sufficient illumination. Keep in mind that when you set the
filmspeed, the flashgun tells you what aperture to set on the lens.
In TTL Auto mode, the T-series flashguns do not use their own light sensor.
Flash control is passed to the camera, the flashgun itself is set to deliver
maximum flash (as if in manual mode), and the camera TTL meter then quenches
the flash when it determines there has been sufficient illumination. Since
that is measure TTL, it would be more 'specific' (which might equate to
'accurate') to the scene and lens being used.
Also keep in mind that TTL Auto is not available on OM1 of any sort or OM3
(though it is available on OM3Ti) or OM10/20/20 while on OM2 it depends on
the shoe/connector in use. If you want to get more detail, the eSIF has an
excellent page titled bodyflashmodetable.htm
--
Piers
-----Original Message-----
From: olympus-owner@xxxxxxxxxx [mailto:olympus-owner@xxxxxxxxxx] On Behalf
Of Simon Worby
Sent: 04 November 2004 21:39
To: olympus@xxxxxxxxxx
Subject: [OM] Re: T32 & T20 "hole" in the "O"
--snip
It must be fairly crude, though. Is the OTF "Auto control by OM-2" more
accurate?
Also (and sorry for the questions) what is it that creates the signal for
the rapid flash to indicate correct exposure? Do to the fact that (IIRC) it
happens on the OM-1N as well as the OM-2N, I assume it's the flash unit
rather than the camera, even in "Full auto control by OM-2" mode.
Thanks,
Simon
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