Nikon/Umax scanners info?????

[Henning Stahlberg]

Hi,

we bought the Nikon Coolscan 8000 recently.

It performs well, if one places the scanner on a massive and firmly
attached table. Otherwise, resolution is quickly lost in Y-direction,
the direction of the negative movement.

On a solid table, the claimed 4000 dpi resolution are met by the
scanner in X- and Y-direction,
but so far I cannot give quantitative information about the MTF.
More detailed tests are under way. At least, after scanning an 300 mesh
TEM grid with the scanner and looking at the FFT of the image, one
can say that there is strong throughput up to the Nyquist frequency in
all directions.

The original negative holder fits only two negatives of 6x13 cm width.
In the beginning I was always cutting the negatives down to that size.
However, it was an easy job for our mechanical workshop to cut the
holder out so that the full Kodak SO 163 negative of 9x13 cm fits into it.
We still can scan only 9000x14000 pixels at 6.35 microns in one go,
but that is enough usually.

The speed is good. Data are transferred to a Macintosh with a
FireWire cable. The Nikon Scan 3 software comes with the scanner
in two macintosh versions: One as a stand-alone program and one as
a Photoshop plugin. The stand-alone version has a horribly slow
saving speed of the scanned image. Saving the image on the disk takes
something like half an hour !!! The Photoshop plugin
version of that same software saves the image using the Photoshop
routines, which then has the usual speed and is fast.
This plugin requires, however, enough RAM memory.
We run that on a G3 Macintosh with 450 MB RAM, and give Photoshop under
MacOS 9.1 some 350 MB RAM. This is the minimum memory for that
application. Better would be still more, like 750 MB.
Virtual memory does not help.
Scanning time for 9000x13000 pixels is about 20 minutes at 16 bit,
and another 20 minutes for the G3 to apply the lookup-table. It seems
as if the scanner first scanns the 16 bit format and applies the
lookup-table in a second phase to the images. Using a faster Macintosh
with still more RAM might probably accelerate the second phase
significantly. Due to this time issue, I scan now with 8 bit
depth resolution, where the scanner software seems to apply the lookup-
table instantly during the data aquisition. The output has then
less than 8 bit depth resolution, probably 6 bit or so. I think,
the data are transfered in 8 bit from the scanner to the Mac and
then transformed with the look-up table to another 8-bit format.
If the look-up table is not linear 1:1, but curved to take the
transmission->OD conversion into account, the 8 bit are reduced.
This 8-bit scanning of the full 9000x13000 pixels takes a few minutes.

The biggest advantage of the Nikon Coolscan 8000 is the price.
It costs about 40 times less than the price of the Z/I Phodis scanner.

The Z/I Phodis scanner is still of much better quality, I think.
Quantitative tests are under way.


Henning.


>I am seeking information about the suitability of the Nikon coolscan 
>8000 and the Umax powerlook 3000 for scanning EM plate negatives for 
>image analysis purposes. Has anyone done any rigorous testing of 
>these machines for these purposes? If so I would really appreciate 
>some tips..... Thanks,
>
>
>Jools
>
>******
>Dr. Julie. L. Hodgkinson, Research Lecturer, Imperial College Sch. 
>Med., National Heart and Lung Institute
>(Cardiac Med.), Dovehouse Street, London SW3 6LY. PHONE:- 020 7351 
>8166 E-mail: julie.hodgkinson at ic.ac.uk
>WEB PAGES   http://www.med.ic.ac.uk/divisions/32/cmjulie.htm 
>http://www.ic-csb.ic.ac.uk/  FAX +44 020 7823 3392
>
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-- 

********************************************************************

    Henning Stahlberg, Ph.D.

    M.E. Mueller Institute for Structural Biology
    Biozentrum
    University of Basel
    Klingelbergstrasse 70
    CH-4056 Basel
    Switzerland

    Tel.: +41-61-267-0949  mailto:Henning.Stahlberg at unibas.ch
    FAX : +41-61-267-2109  http://www.mih.unibas.ch/Homepages/stahlberg

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