ISO question

Does changing the ISO value on a DSLR change a physical property of
the sensor (voltage?) to make it more sensitive? Or is this just a
software-only effect?

Camera I have in mind is the Nikon D2Hs, which is a CMOS.

Thanks!

Dean

On Jul 10, 2:47 am, DeanB <deanbrow...@yahoo.com> wrote:
> Does changing the ISO value on a DSLR change a physical property of
> the sensor (voltage?) to make it more sensitive? Or is this just a
> software-only effect?
>
> Camera I have in mind is the Nikon D2Hs, which is a CMOS.
>
> Thanks!
>
> Dean

No. The chip voltages must be carefully controlled over a narrow
range of tolerance. Changing the ISO makes changes to the file AFTER
reading out the CCD chip. It does nothing to the chip, or the
information while it is in the chip. One can increase the gain of the
analog preamp, or diddle with levels in the A/D converter.