[filmscanners] Re: Multipass scans

["Rob Geraghty" <robg@wordweb.com>]

"Bob Frost" <bobfrost@btopenworld.com> wrote:
>If you had a Nikon LS 4000 (or 2000) as well as 16x sampling, you can also
>increase the analog gain for a scan. So if you have really contrasty
slides,
>you can scan them twice, once set for the highlights, once set for the
>shadows, and then merge them in Photoshop.

I believe the A/D on the LS4000 also has more bits than the LS2000.  It's a
shame I couldn't replace the BIOS chip in the LS30 and make it into an
LS2000. :)  I don't have an LS2000 or LS4000 to try your suggestion with,
but it seems to me that the LEDs can't penetrate the really dense parts of
Provia 100F.  This shows up in Vuescan if you set it to indicate the parts
of the image opaque to IR.  What's the experience of people with LS2000 or
LS4000 scanners and Provia 100F?

There's a merge method posted on the web somewhere for boosting the
highlights which I'ev tried using layers in PSP but it's only as useful as
the amount of shadow information.  With dense slides it usually just shows
up scanner noise in the shadows.

Rob

PS I've noticed an interesting indication of the amount of noise in a
Superia 100 neg compared to a Provia 100F slide.  The uncompressed slide
scans are about 25MB and compress to about 19MB or less with LZW TIFF
compression.  The reduction in size of neg scans is much smaller -
negligible in some cases.  That indicates to me that the information in the
neg scans is a lot more random - ie. grainy.  People on this group have
argued in the past that this represents more information in the neg scan - I
agree, it's more grain information, not more useful information of the
original scene.  Before anyone flames me too much, yes I appreciate there
will be more information in the shadows of the negs, but that doesn't
explain the poor compression.



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