I'm not sure I understand either the question or response entirely,
the language is twisty.
But I have some experience with the K10D and alternative focusing
screens that might prove informative.
The behavior I found when I fitted the DS' focusing screen or my
custom Katz Eye screen for the DS into the K10D is that metering
calibration was off such that the exposure setting was consistently
under by 0.7 EV (I needed to set +0.7EV to obtain normal exposure of a
gray card). With the K10D's standard screen in place, I found its
metering calibration was on the money (0EV compensation required).
I chatted about this with Rebecca Katz and she explained that the K10D
focusing screen was tuned to provide more brightness to the ocular
than the *ist DS screen. Since the metering sensors read the screen
from off the ocular axis, this means the K10D screen's "scatter" was
lower and the metering calibration is setup with that in mind. When
you fit the *ist DS screens, they scatter more, make the metering
sensors think there is more light than there really is, which causes
them to suppress the exposure setting and underexpose.
The odd thing is that with K and M-series lenses, where the full lens
information is not available to the camera due to their lack of the
electrical contacts, the K10D with the older screens proves to be
somewhat more accurate with the green button semi-automatic Manual
exposure procedure than it is with its intended screen. This leads me
to believe that the problem with this green button metering mode is
that they didn't recalibrate it to accommodate the new screen like
they did with the full aperture metering in other modes.
This comes from that forum thang, where I managed to get a 2 point
demerit yesterday for telling a guy to fuck off.
Godders, I must just have been having a shitty day yesterday...
LOL. Yeah yeah, that's what they all say. ]'-)
No offense taken. Or intended on my part either. (Funny how sometimes
people don't realize that.)
Some schmuck on the Leica or Pentax SLR DPRforum didn't like that I
posted pictures to two or three forums. They complained about it, so
DPR's management banned me for a week. I'm finding I'm getting much
more done since I'm not wasting time with the idiocy there, so when my
ban is over I might just go back and tell them all to go fuck off,
seriously, and get banned permanently, to my advantage.
Godfrey
On Apr 4, 2009, at 8:01 AM, William Robb wrote:
In response to this question:
"I was informed that the camera is a little bit under-exposed, but I
want to
know how much. That is, if I set the EV compensation, but how much
(1/3?
1/2?) should I set so that I can get normal exposure?"
This answer was given:
"Well, regarding the exposure problem, let's say it's related to the
lens
used.
For f/3.5-5.6 lens, exposure will be quite good.
But with fast lenses, you'll have a variable amount of
underexposure...
- f/1.4 needs about +1 1/2ev
- f/2.8 needs about +1ev
and so on...
This is due to the fact that the focus screen does not respond in a
linear
way to the aperture of the lens...
You should have a direct relation between shutter speed and aperture
(i.e.
going from f/1.4 to f/2 should halve the shutter speed, going from say
1/1000 to 1/500).
But with the original k20 focus screen, this relation is not respected
(going from f/1.4 to f/2 won't halve the speed).
Note : I'm talking about using actual, stop-down apertures.
For A lenses, the exposure is mesured wide-open, then calculated for
the
given aperture you want to use, so selecting f/2 will always gives
half the
speed of f/1.4.
BUT the wide-open reading will be underexposed by the 1 1/2ev
mentionned
above, so the lens will always underexpose, whatever aperture you're
using.
Using an old lens (with aperture blades actually moving when you
select an
aperture on the lens), you'll see that closing one stop won't halve
the
speed.
You can lessen this behavior by using a LL60 screen (from the *ist
line).
They are fully compatible with the k10/k20, and lessen the
discrepancies to
the point where you won't really need to compensate the exposure
anymore."
--------------------------------------------
I'm not seeing where the answer could possibly be correct, but I
thought I'd
post the whole thing here, hoping to generate some discussion.
This comes from that forum thang, where I managed to get a 2 point
demerit yesterday for telling a guy to fuck off.
Godders, I must just have been having a shitty day yesterday...
William Robb
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