Digital BW, The Print

> > > The Nikon 8000 has analog gain control. I presume that it works
> > > the same way
> > > as you describe it otherwise why call it "analog gain" control.
> > > It will show
> > > more noise in the shadows when set to a maximum
> >
> > Actually, I believe it's misnamed.  This has been discussed with Ed
> Hamrick
> > and should be in the archives.  It does not change the actual
> gain between
> > the CCD and the A/D, but the exposure time.  To quote from Ed
> Hamrick (who
> > wrote ViewScan) from the rec.photo.digital newsgroup:
> >
> > "The "Analog gain" in the Nikon is a bit misleading.  It's actually
> > just the exposure time for each of red, green, blue, and infrared."
> >
> > Austin
>
> In what way can one compare both methods ? Is there a difference in the
> results ?

Hi Ernst,

Yes, there is a MARKED difference in the results.  The "analog gain" that
Nikon has merely shifts the tones up or down the "scale".  Example:

        -
      - - -   - -   - -
    - - - - - - - - - - -
0 1 2 3 4 5 6 7 8 9101112131415

now shift that up:

          -
        - - -   - -   - -
      - - - - - - - - - - -
0 1 2 3 4 5 6 7 8 9101112131415

Same curve, just different "values", but all relative values are maintained.
What it's useful for is getting your entire tonal range within the range of
the scanner...but other scanners do that as well with their exposure
setting.

If the scanner is designed such that it has actual analog gain between the
CCD and A/D, you would EXPAND your analog data, and actually get MORE tones:

    - - -
  - - - - -   - - -     - - -
- - - - - - - - - - - - - - - -
0 1 2 3 4 5 6 7 8 9101112131415

The limit, of course, is our vision (and noise in the CCD/analog
circuitry/AD).  As long as you can get 256 tones out of your data, and you
have tonal "separation" between tones you want to show tonal separation
between...more tones in the image data wouldn't necessarily do you any good.
Again, I understand the Piezo driver claims to give more tones beyond what
you give it for data, to smooth the tonal transitions.

Regards,

Austin