stephan;1219 wrote: The sensor-type (CMOS or CCD) is more relevant for the noise-type than the processor. Leica uses CCD-sensors that have other characteristics than CMOS used in 35 mm DSLR.
And even with CMOS-sensors the noise is increasing with higher ISO, but not as sharp as with a CCD.
Compared, for example, and starting wirh 100 ISO, the S2 behaves almost the same at 200, 400 iso, compared to a Nikon D3x, the spread increases rapidly from 640 ISO upwards. I would say from experience that 800 ISO with the S2 compares to 1200-1600 ISO on the Nikon D3x (and maybe 3200-6400 ISO on a D3S).
Also, resolution and post-processing is an important factor.
btw, ISO-Quality is not a question of S/N-ratio, it is more a stastistical problem of missing and eraticcal data. This is why a CCD-sensor with a lot of pixels can be as good as a CMOS-sonsor with less pixels (up to a certain level, though).
thanks for a reply but perhaps I could understand you better;
First Emil Martin of U of C fame has published a set of curves that plot ISO vs noise here; http://theory.uchicago.edu/~ejm/pix/20d/tests/noise/noise-p3.html#ETTR
and here is a discussion concerning particular cameras and how read noise and ISO effect final S/N; http://www.luminous-landscape.com/forum/index.php?topic=56906.msg460646#msg460646
So for my new Sony A-77 ISO setting is not terribly relevant, Just keep it @ 160 and push the histogram. But I’m wondering about considering the curves in that second reference, what does an S2 or M9 curve look like?
Or do CCD’s produce a different family of curves? In which case, what do they look like and do we benefit more from ETTR or just follow the ISO? If so, where do we max out?
Also, when you say ISO is not about S/N but missing or erratic data, well yes the missing data is the problem but isn’t the result more noise/less picture data? Or is there more?
Sorry to ask such complex questions but I want to get the most out of the camera’s range