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[OM] Re: Scanner sharpness; Silverfast 6.0

Subject: [OM] Re: Scanner sharpness; Silverfast 6.0
From: AG Schnozz <agschnozz@xxxxxxxxx>
Date: Thu, 20 May 2004 07:15:59 -0700 (PDT)
I'm keeping this "on-list" because the VueScan/IT8 subject which
is a bit more universal to those on the list.

> I'm glad the Nik*n LS-20 still lives on. 

Sure does.  It's not the greatest scanner in the world, but with
each revision of Vuescan it gets more useful each time.  Yet,
when I grow up, I'd like to get a REAL scanner like the 5400 DPI
Minolta.  Sharpness, or lack thereof, is my biggest buggaboo
with it.  However, sharpness issues are partly the fault of the
scanner and partly the fault of the interpolator in Vuescan (if
you have it do ANY resizing).

One way to get around the lousy DMAX of the scanner is to do
dual scans with sharply different scanner exposures and do a
layer merge in GIMP or Picture Window Pro.  I've got a project
I'm doing from a series of pictures taken at Picture Rocks. The
extremes of brightness values I'm trying to capture--from white
caps on the water to the deep shadows in the wet rocks are
impossible with a single scan.  For some reason Velvia captured
at least a full stop more information than usual. The only way I
can do these pictures is with dual scans.  If worse comes to
worse, I'll have them drum scanned, but the maximum print size
for any one picture in the set will be no more than 10 inches,
which is quite satisfactory for a 6MP scan

VueScan now gives much better exposure control--in fact with
version 8.x.x. it allows individual "brightness" controls over
the RGB color lamps on Nikon scanners.  In my brief experiments
it's extremely useful as the scanner has a definite color cast
to it which this helps compensate. Also, by increasing the blue
during scanning, I can then reduce this color channel on the
color-tab which lowers the horrendous blue-noise in the shadows.

If you haven't upgraded your copy of VueScan yet, I highly
recommend it--especially as it now supports RAW conversions of
digital camera files--although it is a linear conversion.  A
custom IT8 target calibration with the digital camea will
resolve that issue though.  (now supports Minolta A2)

One technique I've used with VueScan to get the cleanest scans
is to turn the color controls to off on the Color Tab and adjust
the scanner brightness controls to get the scan as clean as
possible.  Only then do I turn the normal color adjustments back
on.

> The IT8 target comes with Silverfast.  I think the SF
> calibration
> routine makes it quite unique as scanning software goes.  I
> have no idea
> how much good it will do you, since Silverfast takes a scan
> and
> references the color swatch points to values in a table stored
> in one of
> the Silverfast folders.

As I understand it, there is only one IT8 color chart with the
squares in specific locations.  I've seen variations with more
squares, but they are off to the side or on the bottom.

VueScan is able to calibrate to an IT8 target.  You scan the
target slide, display the IT8 grid, adjust the grid position and
size to line everything up and select the calibrate function. 
Save this as an IT8 profile for recall.

Same holds for calibrating films.  If you photograph a
calibrated IT8 target, you can scan the negs/tranparancies and
create custom profiles for each type of film being scanned on
that specific scanner.  Ditto on digital camera RAW files. 
Photograph a target and repeat the process.

The hard part is correctly photographing a target.  First of
all, you've got to have a target.  I printed out one, but it's
not very accurate.  Secondly, getting the camera lined up and
you've got to use a lens (or focal length) that produces no
noticable pin-cushion or barrel distortion.

> Let's definitely get together.  Call first as work is making
> me nuts right now and the house is torn up. 8^0 

It's looking like post-vacation at the moment.  Heading off for
points north.  Porcupine Mountains, waterfalls, Lake Superior,
hiking, bicycling, camping, photographing and 4-wheeling.  I've
lot's of Velvia burning a hole in the fridge and a darkroom
wanting some new B&W negs to process.  Depending on space, I may
or may not take the 4x5.  (ya right, like I'm going to leave
that home).
 
> I could definitely use a short trip somewhere in a Jeep.

Construction sites with big mounds of dirt work for me too.

Hey, have you photographed the new dome yet?

AG-Schnozz


        
                
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