Arrrrgh... SF AI Studio Image scaling to max size HOW?

All the problems with Nikon film scanners

hassiman
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Arrrrgh... SF AI Studio Image scaling to max size HOW?

Postby hassiman » Sun May 11, 2008 2:31 am

Hi,

I have been try to figure out what should be simple... but for some reason seems to be about impossible. I was wondering if any other SilverFast AI Studio/CoolScan 9000 user has figured it out.

I am scanning 35mm and 6X6 transparencies. I would like to scan for maximum quality/enlargement size. I mostly scan full-frame with little or no cropping.
I am trying to figure out what settings to use to scan at the Nikon 9000 scanner's maximum optical quality without interpolation. The Silverfast techs have said that 4000 dpi is actually over the true optical resolution for the 9000 and suggested that 3600 was a more realistic figure.. maybe even 3000 dpi.

I am scanning using the 48 Bit Color setting. Not HDR.

In SilverFast's "frame" options field:

I have set both "scale %" fields at 100.0

I must assume that the data in the "original" fields is generated by the dimensions of the cropping frame on the image preview.

I have tried to set the output fields... but I am not sure how it works.

My Q factor is set at 1.5 with "screen" reading 2400

The dpi figure I have typed in as 3600 as the slider will not give me that figure.

Dopes anyone know the magic formula or input sequence I need to follow generate maximum quality scans from 35mm and 6X6 transparencies? :o

degrub
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Location: Texas

Postby degrub » Sun May 11, 2008 4:23 am

double check, but i think the sensor on the 9000 is 4000 ppi in single line mode. i don't know if the other rows of the sensor are lined up the same. If they are, then you want to sample at a multiple of two of the sensor elements. Otherwise you are asking the Nikon driver to average the results between two ccd elements to give a RGB value. That is the tradeoff. Sampling at 4000 ppi may be oversampling because of the limits of the optics, so the scanner is just sampling some noise and possibly degrading the sharpness of the image. i have not seen any real practical distinction in my CS5000 (which resolves detail to about 2700 ppi) when i sample at 4000 ppi. i use PS to downsample to whatever i need. i think this is better than sampling at 2000 ppi and giving up some pixels to stay within the optical resolving capability of the scanner. For MF film, it may make sense to sample at 2000 ppi since the enlargement factor is smaller for a given print size.

DO a search on the archives of comp.periphs.scanners and look for messages by Kennedy for technical discussions of the issue

http://groups.google.ca/group/comp.periphs.scanners/


Also, you can search the web for "scanner bakeoff" and "scanner mtf"

http://elbereth.obspm.fr/~kervella/Scan ... lation.htm

http://www.users.qwest.net/~rnclark/scandetail.htm

http://www.normankoren.com/Tutorials/MTF2.html

i have always ignored Q factor and just set the ppi i need for the scan.

i don't have my scanner up, but if i remember correctly the slider only gives values that are sensor max ppi / 2 or 4 or 8 etc. ( also 2x)

LSI_Muenier
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Joined: Wed Feb 13, 2002 1:00 am

Postby LSI_Muenier » Tue May 13, 2008 7:38 am

Dear hassiman,

if you would like to scan at the optical resolution of the scanner, you may perform as follows in SilverFast:
- set Scale to 100%
- drag the resolution slider to the rightmost position (this is then twice the optical resolution)
- drag the resolution slider one step back to the left -- there you are.

For best results, please consider to activate the checkbox "SuperFineScan" in the Options "Special" panel. The scans then lake longer, but are a bit smoother.

Best regards
Martin

hassiman
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Posts: 78
Joined: Wed Feb 27, 2008 7:15 am

Scaling problems

Postby hassiman » Tue May 13, 2008 5:52 pm

Again taking into account that this is a Nikon SuperCoolScan 9000
Would these setting be equivilant to :

Scaling set to 100.0

QF set to 1.5

dpi set to 3000


At these setting what would the biggest enlargments be for a full frame scan of a 35mm? A 6X6?

degrub
SilverFast Master
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Posts: 597
Joined: Fri Dec 21, 2001 1:00 am
Location: Texas

Postby degrub » Wed May 14, 2008 1:39 am

most printer drivers are happy with 300 ppi input so
3000 ppi/300 ppi = 10 inches on the short side of 35mm

60 mm frame ~2.4 inch if i did the math correctly
so 2.4*3000ppi/300ppi = 24 inches on the short side :)


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