> OK, I'll accept that I'm 100% wrong if you'll accept my personal
> statement that all of the wrong crap I'm doing still just happens to
> work for me. :-)
Just because a person hasn't experienced or recognized the problem
doesn't mean that it doesn't exist. In my day job, I'm expected to
know that enough about any given technology to avoid weaknesses that
the specifications say don't exist. (I just got done dealing with that
very issue with a massive top-grade, most-expensive fiber-optic system
out there where the manufacturer said "well, yes, I know we said it
could do that, but you should know that this technology never really
works exactly as we say it is supposed to, so suck it up and spend
another $250,000 on the turnup of that circuit because it only goes
600km between regens, not 6000km like we said it did. Sunspots, you
know.) You have bought into the lie that the histogram is true and for
what you've shot, it is true enough that you won't know any different.
It's usually right, so it is a relatively accurate guide in most
situations. But you would have to admit that there are certain
circumstances where the results aren't quite what you expected. Right?
Come on, I can't be the ONLY person on this list who has been
surprised when that carefully shot ETTR image ended up as a tosser.
All this rolls back around to the original point of discussion which
is ISO ratings. Unless you are borderline insane, there is no way that
even the most rabid OCD person is going to be able to use the DXOMARK
ISO ratings and apply them to real life. It just isn't going to
happen. And if you do, you certainly aren't going to do it with an
in-camera meter, but most likely with a calibrated Sekonic Spot-Meter.
The issue is that DXO's ISO ratings are for the saturation point of
the sensor, but all in-camera meters are based on 18% (give or take
depending on what you use as your midtone standard). While I
appreciate what they have done in their testing, it still doesn't hide
the fact that their ISO ratings have absolutely no application that I
can think of in real life. Except for the limited applications which I
already identified.
But DXO's hands were somewhat tied because the manufacturers will game
the midtone settings to apply curves to protect the highlights or
shadows. This is well documented about the EM5, for example. (Yes,
Moose, even Ctein wrote about it about the time he discovered some
weird motion blurring that he couldn't explain). The saturation point
measurement may actually be the only thing they could use. But the
results of it are more for calculation of dynamic range than for any
practical purpose. It's not something you are going to dial in on your
ISO dial. (Oooo oooo DXO says that 100 is actually 125 so let's dial
that in..... hmmm... why are my pictures all dark?)
--
Ken Norton
ken@xxxxxxxxxxx
http://www.zone-10.com
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