[Leica] DxO, the M8 and dynamic range

[rgacpa at yahoo.com (Bob Adler)]

Geoff and Don,
Daring to jump in between the dog and the tree here, just as different films 
behave differently, different sensor and the firmware interpreting behave 
differently. I find that just like film, bracketing, if time permits, is 
best to do. Obviously for most photo journalists and street photographers, 
this is not possible. For my landscape shooting it is and I use it. I do 
start at -1/3 and bracket in half stops via shutter speed...
Probably obvious, but just felt a need to jump in with my experience.
Best,
Bob

 Bob Adler
Palo Alto, CA
http://www.raflexions.com




________________________________
From: Geoff Hopkinson <hopsternew@gmail.com>
To: Leica Users Group <lug@leica-users.org>
Sent: Tuesday, January 20, 2009 3:55:58 AM
Subject: Re: [Leica] DxO, the M8 and dynamic range

Don, thanks for your input there. I don't recall that discussion on the
sensor in detail. I have found the test site referred to by Dante which is
very interesting. I did locate the LFI discussion regarding the non-linear
way the sensor information is compressed into its 8 bit form before later
reconstruction. I won't pursue this longer on the list.
Of course in all of this I was explaining a method that I prefer rather than
expecting to convert anyone else. The majority of folks look to be
comfortable with the negative exposure adjustment method.
The whole area is a complex one and we each place different weight on
different attributes, I think. Noise in shadows being exacerbated by
under-exposure is a big issue for me. Sometimes too simple assumptions
regarding terminology differ too. For example 'over-exposure'
Methods as well. I use Auto exposure but try to meter carefully and then
lock that reading and recompose (where practical and warranted).

2009/1/20 Don Dory <don.dory@gmail.com>

> Geoff,
> If you recall from the discussions of the Kodak sensor when the M8 was
> originally announced one of the technical items that stood out was that the
> bias was toward the low end of dynamic range.  Most sensors show a bias one
> way or the other and the Kodak sensor in the M8 does a better job
> distinguishing small differences in light values in the dark areas than in
> the light.  Which is why most of us have dialed in a negative exposure
> compensation to avoid blowing the highlights.
>
> On Tue, Jan 20, 2009 at 1:34 AM, Geoff Hopkinson <hopsternew@gmail.com
> >wrote:
>
> > Dante can you point me to some good data/analysis/examples that have
> > brought
> > you to these conclusions? I'm very keen to get the best from my M8 and
> > these
> > statements don't fit with my understanding at all.
> >
> > 2009/1/20 Dante Stella <dstella1@ameritech.net>
> >
> > >
> > > The DxOMark site is interesting, primarily the DR comparisons.  Run a
> > > comparison on the M8 against any modern DSLR (Nikon or Canon) and
> puzzle
> > > about the arguments/assertions that the dynamic range of a Leica is
> > > "better."  A better word would be "average."  Compared to cameras
> > equipped
> > > with Kodak's 24x36 sensors, Fuji's Super CCDs, and Nikon's post-D2x
> > sensors,
> > > it's actually a bit behind the curve.  I'm sure that despite objective
> > > comparisons like DxO's, we're still going to hear claims that the M8 is
> > > notable for its "dynamic range" (c.f. here, the Leica Camera forum, and
> > > RangefinderForum.com).  Or does someone want to poke holes in DxO's
> > > methodology?
> > >
> > > After two years of working on M8 DNG files, I can say that the DR and
> > > distribution of information in DNG files are my biggest issues with the
> > M8.
> > >  It's not the spatial resolution or the sensor size.  It's not even the
> > > rickety 50-year old rangefinder, a different effective back focus, or
> an
> > > annoying bottom-plate load.
> > >
> > > Many of us like shooting pictures that have tonality in the highlights.
> >  On
> > > film, we'd use TMY, shoot normally, and err on the short side of
> > > development.  No problem.  But on an M8, we have to underexpose.  This
> > > pushes the moderately low tones down into the noisier nether regions -
> > and
> > > some of the time, we end up needlessly sacrificing the camera's DR in
> the
> > > process just so we can be sure we don't blow it on the high end of the
> > > scale.
> > >
> > > On the next Leica digital, we need more bits, and we need them in the
> > > highlights.  That way, we can shoot for the shadows and simply reign in
> > any
> > > unruly highlights.  And by reign in, I mean with both color and
> tonality.
> > >  When you recover highlights on an M8 as currently configured, you get
> > color
> > > (if you're lucky), but the tonality is flat - like film that shouldered
> > off.
> > >  Not good for things like clouds and snow-capped mountains.  Or human
> > faces
> > > with hot spots.
> > >
> > > I'm still puzzled about why Leica decided to so much information to
> > > shadows.  Pictures taken in bright light generally don't have a lot of
> > > shadow interest.  Low-light situations are either "all shadows," in
> which
> > > case they can be shot normally (since they have very constrained
> dynamic
> > > ranges) - or they are mostly shadows with bright highlights - in which
> > case
> > > you need more highlight recovery.  So what was the imagined situation
> > that
> > > prompted the composition of Leica DNG files?
> > >
> > > Dante
> > >
> > > ____________
> > > Dante Stella
> > > http://www.dantestella.com
> > >
> > >
> > > _______________________________________________
> > > Leica Users Group.
> > > See http://leica-users.org/mailman/listinfo/lug for more information
> > >
> >
> >
> >
> > --
> > Cheers
> > Geoff
> > Life's too short for slow zooms
> >
> > _______________________________________________
> > Leica Users Group.
> > See http://leica-users.org/mailman/listinfo/lug for more information
> >
>
>
>
> --
> Don
> don.dory@gmail.com
>
> _______________________________________________
> Leica Users Group.
> See http://leica-users.org/mailman/listinfo/lug for more information
>



-- 
Cheers
Geoff
Life's too short for slow zooms

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