You "touch" a very interesting subject.
-multi-spot metering-
I will like to find a conclusion about
"how finally we are going to use the F280"
with few words, something that we can remember very easy
and then we can go and speak more about
spot metering and how this really works with very few words.
For example I have some simple questions.
Why OM have +2stops/-2Stops ? (and not +-4 stops for example)
Why the highlight button is going -2 2/3 stops ?
Do you use the +-2Stops ?
> The OM manuals give the impression that there's something "magical" about
> multi-spot metering -- all you have to do is spot-meter every important
area in
> the picture, then (if you like) take a few extra readings of those areas
you
> want to have good detail in (highlight and/or shadow), and the camera will
> miraculously give you an aesthetically pleasing exposure.
The thruth is that OM Manuals they give the right way to shoot but they
don't explain the reason "why they do that?". Why they chose this spot point
and not some other ?.
So I strongly belive that OLYMPUS never "teach us" the "theory" behind the
spot mettering, because if they have did then more people they chose the OM
system with multi-spot mettering - exacly as OM have create it, because this
is the best so far I have found on cameras.
Babis
----- Original Message -----
From: "William Sommerwerck" <williams@xxxxxxxxxx>
To: <olympus@xxxxxxxxxxxxxxx>
Sent: Tuesday, April 23, 2002 00:55
Subject: [OM] variation in F280 duration; multi-spot metering
> "It is mentioned in the Olympus OM System brochure. See the following link
for
> a scan of the F280 data.
>
> http://www.glink.net.hk/~photogrp/F280.jpg
>
> The F280 is intelligent in Super FP mode, the flash duration varies, you
can
> even get higher GN with OM707."
>
>
> The guide number listing for Super FP mode shows that the square of the
guide
> number divided by the shutter speed is a constant at all shutter speeds.
This
> means that, even if the duration of the Super FP flash varies, it has _no_
> effect on the flash's output.
>
> So the question of _why_ there is a difference in duration remains.
>
>
> "It would seem logical that since the F280 acts like a constant light
source
> added to the picture its light would be added into the automatic shutter
> calculation. That would certainly increase the number of successful F280
> exposures. Otherwise Olympus would have to use the extra contact on the
flash
> to cause the automatic setting of the shutter to ignore light from the
flash
> and how would they do that? Easier just to let the camera operate normally
> integrating all the light in the scene into the final shutter
calculation."
>
> This is almost certainly correct. However, there's a subtle point to this
issue
> that's easily overlooked.
>
> Fill-in is almost always used for objects or people near the center of the
> frame. (That is, unless you're photographing a group hug, there are rarely
> things near the edges of the frame that intercept the fill light.) If auto
> operation gives a shutter speed of (say) 1/500, the second curtain will be
> released before the first curtain has travelled even 1/8 of the way across
the
> frame! As this part of the picture is unlikely to contain anything the
fill-in
> flash is illuminating, the light from the flash will have _no_ effect on
the
> exposure.
>
> If you don't mind my getting a bit off-topic, the same issue could be
raised
> about non-flash OTF exposures. At auto shutter speeds above 1/60, the
exposure
> is actually determined by the light striking the right side of the film
plane
> (as seen from the back of the camera)! At 1/1000, less than 3mm's width of
the
> film-plane area determines the exposure.
>
> To put it another way -- if there were a very bright light (or unduly dark
> area) at the extreme left side of the scene you're photographing, you'd
wind up
> with an underexposed (overexposed) picture -- "center-weighted" readings
> notwithstanding!
>
>
> I appreciate Mr. Swier's intelligent remarks. Perhaps we will gradually be
able
> to fill in the gaps about how the F280 "really" works.
>
>
> "William said: "multi-spot metering -- both are terrific ideas, but they
don't
> _quite_ work they way you think they "should"... Have I missed something?
Why
> doesn't multi-spot work the way I think it should?!"
>
> That _was_ a rather presumptuous statement -- I can't read other people's
> minds. What I should have said is that it doesn't work the way Olympus
would
> like you to think it works.
>
> The OM manuals give the impression that there's something "magical" about
> multi-spot metering -- all you have to do is spot-meter every important
area in
> the picture, then (if you like) take a few extra readings of those areas
you
> want to have good detail in (highlight and/or shadow), and the camera will
> miraculously give you an aesthetically pleasing exposure.
>
> This cannot always be true. If the highlight and shadow areas span a
brightness
> range that's wider than what the film can record, there's no _single_
exposure
> that can capture detail in both areas. (Note that some digital cameras
provide
> for two exposures to capture highlight and shadow detail, which can then
be
> melded with the appropriate software.)
>
> Nor is the effect of multiple readings of the same area obvious. Suppose
you
> take a reading of the brightest highlight, then take one of the darkest
shadow
> area, then finish with a second reading of that shadow. The darker the
shadow
> area relative to the highlight, the more the second reading of it will
"bump
> up" the overall exposure. This means that the exact aesthetic effect of
> multl-spot reading is not easy to (pre)visualize.
>
> As I see it, the major advantage of multl-spot reading is that it lets you
> easily analyze the image, so you can intelligently choose the appropriate
> exposure. For example, you can read the highlights and shadows, then see
where
> the mid tones fall with respect to them. No other camera offers anything
even
> remotely like this. It's certainly a lot easier than fiddling with a
hand-held
> spot meter!
>
>
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