At 23:11 4/15/99 , Michael wrote:
>Thanks for the posting re: T32 fill flash in daylight.
[snip]
>When using your set-up what is the significance of leaving the T32 off
>untill the camera settings are made? Wont the OM2n stay on 1/60 if the
>viewfinder needle says so, even if the compensation ring is turned? What
>effect on the camera does leaving the flash ON or OFF have?
>
>I have an F280 and OM3Ti but have never used them together as a daylight
>flash combo. As I dont have a manual for the F280 I dont know the correct
>process for setting up for fill flash. But then again I have a manual for
>the T32 and it does not explain anything in much detail and certainly not
>the procedure you submitted.
[snip]
You're welcome. It's a procedure that a friend at work (who uses a Minolta
with dedicated TTL flash and I discussed and then walked through its basic
logic several times. As it is a multi-step process, this is very likely
why you do not see it in instruction manuals. If the manual even gets read
(!) many users just want a single-step procedure such as a switch to flip
or knob to twist. Anything else generates more questions on the "help line."
The OM-3[ti] is a manual camera with mechanical shutter and coupled meter.
I do not believe it has any TTL/OTF flash control. My F280 manual doesn't
even mention the OM-3[ti]. Olympus America's web site mentions the F280's
OTF and Super-FP modes for the OM-4T, but only its Super-FP mode for the
OM-3ti. Not knowing the OM-3[ti] I left it off the list. I presume that
even with an F280 you must use GN's with the OM-3[ti] for normal flash
operation. Three things are required of the flash and body to make the
method I described work:
1. TTL/OTF flash control modes in the flash and camera body.
2. The dedicated flash locks the camera body's shutter speed at 1/60th
second, either when it is turned on or when it is on and ready (charged).
3. An EV or exposure compensation adjustment of at least a stop if not
two. Increments of 1/3 or 1/2 stop are desirable.
Hmmmm . . . OM-2n. The instructions were written based on my OM-4 and what
I know the T-20 and T-32 do with the AE OM's when you turn them on. In
auto mode, with the flash off, a string of LED segments illuminate above
the shutter speed numbers in the OM-4 indicate a changing shutter speed as
you turn the aperture ring. The needle in your OM-2n moves up and down to
show the shutter speed that would be used.
With both the OM-4 and OM-2n, when you turn the flash on it locks the
shutter speed to 1/60th. On the OM-4 it adds left and right arrows around
the 60 in the viewfinder's shutter speed display:
[ 250 125>60<30 15 ]
After the flash is charged, a red LED ready light appears on the far right.
Your OM-2n should have a similar LED, though I believe it is on the left
side, that indicates "flash ready." On the OM-4, the LED segments above
the shutter speed numbers will still show the *non-flash* shutter speed
that would be used if the flash were turned off even after the flash is
charged, but the left and right arrows around the 60 indicate the shutter
speed is locked on 1/60th. If your meter needle still moves to show a
non-flash shutter speed when you rotate the aperture ring, even with the
flash unit on (just as the LED segments in my OM-4 do) it doesn't matter if
the flash is on or off when you select the aperture.
However if you press the shutter release with camera in Auto mode and flash
*on* in Auto TTL mode, you will always get 1/60th second shutter speed
regardless of what the viewfinder needle points to (or in the case of the
OM-4, what the LED segments indicate). Yes, the camera will stay at 1/60th
with the flash on even if you move the EV compensation ring. Indeed, this
is what you want.
It *does* matter when you turn the EV compensation ring. You want to find
the aperture that will give you a 1/60th shutter speed for the film speed
in the camera before turning the EV ring. This ensures the film would be
properly exposed to the overall scene at 1/60th second if the flash was
left off. By turning the ring, you reduce the amount of light the flash
will emit. This allows the flash to fill in foreground shadows while
obtaining the bulk of the overall exposure from ambient light.
How much light comes from ambient versus flash, especially in the
foreground, will depend on how far you turn the EV ring. The farther you
turn the EV ring clockwise in the minus direction, the less light you will
get from the flash. If I've done the math correctly, -1 EV tshould be
approximately 2:1 ambient to flash ratio. At -2 EV the it should be
approximately 4:1 ambient to flash ratio.
I have not done a formal "A vs B" test under tightly controlled conditions,
but this method has given results that satisfied both me with my OM-4,
T-20, T-32 and F280 and my friend with his Minolta and its dedicated TTL
controlled flash. This is why I suggested experimentation under some
different conditions prior to trying it on important or critical shoots.
You will have to decide how much fill you want based on what pleases you.
You may also decide this method doesn't achieve what you want (too much
fill flash even at -2 EV) and you will have to use your GN method. You may
run into trouble if you use higher speed films, especially on a very bright
sunny day, unless you have a ND filter (in a pinch you can use a
polarizer). I use Kodachrome 64 so I rarely have any trouble stopping down
to an aperture that would produce a 1/60th second shutter speed.
Your method is a standard one, allows a lot of control over the ratio, but
takes too long for me under most conditions. My victims (subjects)
normally won't sit still long enough for me to do all the math and set the
aperture.
Hope this helps with the procedure.
-- John
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