"John Sheehy" wrote in message
...
"DRS" wrote in
. au:

Why do Nikons seem to have a base ISO of 200? Is it a trade off of some
kind?

The D3 uses a low silicon fill factor, and makes up for it with large
microlenses, which, of course, fill the wells faster. In order to meter
at
ISO 100, the camera would have very little RAW highlight headroom, so ISOs
under 200 are only offered as special modes. Apparently, they use the low
fill factor to get more noiseless electronics at the photosites. This
keeps read noise down a bit, but increases shot noise a little, too.



Would you please explain this concept in English? I know about SNR and why I
get more noise at a higher ISO, but I don't understand the difference
between read noise and shot noise.

--
Peter