Archived posting to the Leica Users Group, 2010/04/28

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Subject: [Leica] Exposure comp and the M9
From: hopsternew at gmail.com (Geoff Hopkinson)
Date: Thu, 29 Apr 2010 14:33:04 +1000
References: <mailman.1117.1272465035.89760.lug@leica-users.org> <4BD85A16.2050503@verizon.net> <r2w73301d6b1004281143yc63d96dmcf1d60207e764386@mail.gmail.com> <z2z36172e5a1004281803tf7979ec1w34ba409fc109738c@mail.gmail.com> <541613.62508.qm@web82104.mail.mud.yahoo.com> <787764.40763.qm@web82106.mail.mud.yahoo.com>

WARNING long technical rant.

Bob I think that Henning is unconvinced as well, from when this came up
before. I didn't want to open that particular bucket of photons again, hence
I said, in my experience. Here I go opening the bucket again.

It is true that the settings for JPG are unavailable when shooting DNG with
the M8/9. White balance, colour space, contrast, sharpening etc. As far as I
know those settings are also ignored in dSLRs when shooting Raw but maybe
their menus are more friendly/feel good!

In the latest M9 firmware, even if you select AdobeRGB as your colour space
for JPG the greyed out option for colour management for DNG now shows sRGB
which is certainly not true for the DNG (and you have to reset it every time
you shot Raw and then were shooting JPGs but wanted the broader colour
space).

As you know White Balance is not set in Raw, only instructions noted on what
selection was made in camera. AFAIK the Colour Space is irrelevant.
Internally LR operates in own linear version of ProPhotoRGB but that may
belong in another rant ;-)  It cannot be affected by WB because otherwise
your Raw file would be potentially throwing away information (very cool
colours at one end or very warm at the other). The Raw file is identical in
every respect except for that single instruction.  Actually I don't know
what the embedded profile does. I can ask a real expert. If I can understand
his explanation I shall pass it on.

The M8/9 are both capable of recording colours outside the AdobeRGB colour
space and that information is retained in your Raw files. That's why we
choose the broadest possible space for converted output if that is
important. Easy to demonstrate if you shoot some very saturated yellows for
example and then observe the clipping indications in your converter preview
(ACR or LR) when you select different output colour spaces smaller than
ProPhotoRGB.

With the M8 at least if you have auto preview enabled you can clearly see
the LCD update the displayed preview image after a couple of seconds. I
believe that it is applying the JPG conversion settings (default and/or
perhaps your selections?). I can't say that I have observed this personally
with the M9 but then I never use auto review any more. Try a test shot
(still DNG) of the same subject e.g. interior lit with fluorescent with
different WB selections. The camera appears to be applying the white balance
setting to the preview. Clearly you  are also getting a gamma curve applied
for a start. The Raw file is being converted or you wouldn't see the
exposure correctly (or at all with your human vision).
Try shooting with a selection of DNG AND JPG. What do you see on the LCD
preview? In a controlled setup, check if the clipping warning is identical?
My technical German is ceratinly not up to asking any Leica engineer about
this but I can pronounce Summilux and Bo-keh OK 3 times out of 5.

Now I think I'll have a little lie down for a while ;-) Someone who actually
understands the camera electronics and firmware will doubtless tell me why I
am making the wrong conclusions or the right ones for the wrong reasons or I
am just plain wrong.


Cheers
Geoff
http://www.pbase.com/hoppyman


On 29 April 2010 12:13, Bob Adler <rgacpa at yahoo.com> wrote:

> See last sentence:
> http://tinyurl.com/M-histogram
>
>  Bob Adler
> Palo Alto, CA
> http://www.rgaphoto.com
>
>
>
>
> ________________________________
> From: Bob Adler <rgacpa at yahoo.com>
> To: Leica Users Group <lug at leica-users.org>
> Sent: Wed, April 28, 2010 7:09:17 PM
>  Subject: Re: [Leica] Exposure comp and the M9
>
> Hi Geoff,
> I thought that the M was just about the only camera that based the
> histogram on the raw data. Not sure where I read that, but I remember
> posting it on Michael Frye's site as a question as he was telling everyone
> how to set their camera to get a more accurate histogram for raw shooting.
> He agreed the M showed raw histogram. Maybe you can ask your Leica gang?
> Best,
> Bob
> Bob Adler
> Palo Alto, CA
> http://www.rgaphoto.com
>
>
>
>
> ________________________________
> From: Geoff Hopkinson <hopsternew at gmail.com>
> To: Leica Users Group <lug at leica-users.org>
> Sent: Wed, April 28, 2010 6:03:24 PM
> Subject: Re: [Leica] Exposure comp and the M9
>
> Stan I don't routinely underexpose but there are practical reasons why many
> excellent photographers do and they consider the trade off reasonable.
> Clearly it works.
> To add to what Bob and Tina have said, while you can and probably will
> routinely recover some detail in your shadows, at high ISO values,
> underexposure then recovery worsens noise there. That may or may not be
> significant and you can clip the shadows in Post to ameliorate that if
> desired. Another trade off.
> I would also add that in my experience, the clipping indication on your
> camera LCD histogram is conservative as the preview is based on the jpg
> conversion settings of your Raw file.
>
> Obviously only you can be the judge by experience of what works best for
> you
> with your equipment, technique, subjects and intended output.
>
> Cheers
> Geoff
> http://www.pbase.com/hoppyman
>
>
> On 29 April 2010 04:43, Tina Manley <images at comporium.net> wrote:
>
> > I used to underexpose by 1/3 and sometimes 2/3 stop.  But I no longer do
> > that.  LR3 is so good at recovering highlights that I don't worry about
> it
> > anymore and I think the files are better exposed correctly.
> >
> > Tina
> >
> > On Wed, Apr 28, 2010 at 11:53 AM, Stan Yoder <s.yoder at verizon.net>
> wrote:
> >
> > > The conventional wisdom with the M8 (which I followed) was to
> underexpose
> > a
> > > bit to make sure highlights weren't blown, then resurrect shadow detail
> > in
> > > post. Also, some felt that underexposing at high ISOs kept the noise
> > down.
> > >
> > > So, to those of you with M9s, are you continuing to do that for either
> or
> > > both reasons (assuming you did so with your M8s)? Or do you no longer
> > find
> > > it useful or necessary?
> > >
> > > TIA,
> > > Stan Yoder
> > >
> > > BTW, great to meet some of you at the Savannah LHSA shoot.
> > >
> > > _______________________________________________
> > > Leica Users Group.
> > > See http://leica-users.org/mailman/listinfo/lug for more information
> > >
> > >
> >
> >
> > --
> > Tina Manley, ASMP
> > www.tinamanley.com
> >
> > _______________________________________________
> > Leica Users Group.
> > See http://leica-users.org/mailman/listinfo/lug for more information
> >
>
> _______________________________________________
> Leica Users Group.
> See http://leica-users.org/mailman/listinfo/lug for more information
>
>
>
>
>
> _______________________________________________
> Leica Users Group.
> See http://leica-users.org/mailman/listinfo/lug for more information
>
>
>
>
>
> _______________________________________________
> Leica Users Group.
> See http://leica-users.org/mailman/listinfo/lug for more information
>


In reply to: Message from s.yoder at verizon.net (Stan Yoder) ([Leica] Exposure comp and the M9)
Message from images at comporium.net (Tina Manley) ([Leica] Exposure comp and the M9)
Message from hopsternew at gmail.com (Geoff Hopkinson) ([Leica] Exposure comp and the M9)
Message from rgacpa at yahoo.com (Bob Adler) ([Leica] Exposure comp and the M9)
Message from rgacpa at yahoo.com (Bob Adler) ([Leica] Exposure comp and the M9)