> If anyone has a Nikon D3S or is considering getting one, the
> results would likely be worth a look at http://www.embedinc.com/d3s.

Your examples show up your film background... Image sensor's
native speed may not be in the 100 / 200 / 400 sequence.  Higher
& lower speeds are created by applying gain & anti-gain via the
electronics to match common & expected ISO speeds.

Sensor's native speed may be ISO 160, so that may have lower
noise then ISO 100 (e.g. to get ISO 100, sensor is used at 160
then sensitivity is processed down).  Each processing step can
increase noise or reduce quality.  Entire article on this in
a very recent Digital Photo Pro magazine.

I know I hadn't thought of digital SLR "native sensor speed" in
anything but old 100 / 200 / 400 film speed sequence until I
read about it recently.

So you may want to repeat your tests at other ISO settings and
look for lowest noise value.  Modern digital SLR sensors are so
good that you may not be able to see a difference at "low" (say,
under 800) ISO settings.

As far as I know, neither Canon, Nikon, or other major brand
release data on the native sensor sensitivity.  So you can't
just go look it up in the datasheet. <sigh>

						Lee Jones
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