Archived posting to the Leica Users Group, 2012/09/02

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Subject: [Leica] Light metering with the Leica M9
From: hopsternew at gmail.com (Geoff Hopkinson)
Date: Mon, 3 Sep 2012 16:35:45 +1000
References: <6883F953-1EC3-433E-9CFB-4642A0B9276E@mac.com> <CC6919E4.2312B%mark@rabinergroup.com> <CAJ3Pgh4Fh9iq1w5m1MTg2hOYDwAfv65zcnRVuPrRAD9er7tZHA@mail.gmail.com> <CA+yJO1CrcpN44a1RO38SiGdGsD1DWQg4439W6C_bwKXGh1qjMw@mail.gmail.com> <CABmfTOWPWnARi=ODsbU3J6ofCFh3zHZ3EgGAJXbdJWDc-wrxRA@mail.gmail.com> <CAJ3Pgh5QJP2JFu2rJgHyJG1mv4v=zktEQoVxihrpo5+vn+fPig@mail.gmail.com>

On the M9 histogram, I would humbly add that while I may be able to recover
where just one channel is clipped this amateur treats that as a get out of
jail rather than routine option. Clip two and the situation is potentially
worse of course. Then you get into how many values your output device
(monitor/printer) can actually display anyway. The histograms seen in Raw
processors are different and generated in a different way, plus are program
setting dependant anyway (as I'm sure that you know).  All of which makes
my brain bleed a little, so I guess continuing to take the camera histogram
as a guide and just avoiding that hard clipping where relevant is better to
cope with as a practical matter.

If you have preview display on by default, once the low resolution preview
is generated for the LCD (and you can see the display change WB for example
as that happens) you can also see the histogram for just part of the frame
when you zoom the preview.

But then none of that demosaicing is going on with the Monochrom. Each
photosite generates one grey value with no interpolating an R,G or B value
from an adjacent photosite of same 'colour'. Erwin Puts has some
interesting comment on a possible effective resolution change due to that
too. Then there is no 14 BIT/8 BIT voodoo going on either, so it really is
a different kettle of fish. Someone send me one and I promise to test it
out and report back ;-)

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



On 3 September 2012 15:20, Paul Roark <roark.paul at gmail.com> wrote:

> Marty Deveney <benedenia at gmail.com> wrote:
> > I've found Leica's histograms harder to come to terms with ...
>
> As a practical matter, they seem to work.  I wait a few seconds for
> the test shot to be processes, and then hit the "Play" button and then
> the "Info" button.   You can then adjust the exposure as needed to get
> the histogram to the right edge, but not clipping.
>
> As I understand it, the M9 histogram is actually the Jpeg histogram.
> As such, you have some extra you can pull out of raw file with
> "recovery," which taps into the fact that one of the R, G or B
> channels may not have been blown out.  The MM, however, does not have
> that extra margin of safety.  So, with it, you have to be very careful
> that the histogram is is not clipping (hitting the right side of the
> graph.  The issue with the MM may be that you'd want a 1/16 or an inch
> or so gap between the apparent histogram end and the right side to be
> sure there are not small area of brightness than just don't show up
> enough on the graph.
>
> But, again, the bottom line for me is that with the use of the
> histogram, I never have a problem.  It simply works.
>
> Paul
> www.PaulRoark.com
>
> _______________________________________________
> Leica Users Group.
> See http://leica-users.org/mailman/listinfo/lug for more information
>


Replies: Reply from benedenia at gmail.com (Marty Deveney) ([Leica] Light metering with the Leica M9)
In reply to: Message from scottgregory at mac.com (Scott Gregory) ([Leica] Light metering with the Leica M9)
Message from mark at rabinergroup.com (Mark Rabiner) ([Leica] Light metering with the Leica M9)
Message from roark.paul at gmail.com (Paul Roark) ([Leica] Light metering with the Leica M9)
Message from images at comporium.net (Tina Manley) ([Leica] Light metering with the Leica M9)
Message from benedenia at gmail.com (Marty Deveney) ([Leica] Light metering with the Leica M9)
Message from roark.paul at gmail.com (Paul Roark) ([Leica] Light metering with the Leica M9)