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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