filmscanners: Nikon IV test results

[Mike Duncan <mgduncan@esper.com>]

Early tests using the Stouffer gray scale obtained with Vuescan (Slide
setting and B&W=0.001) show exceptional linearity down
to an OD of 2.11, then an abrupt flattening of the curve above that.  Using
OD axis, the sensitivity is actually highest between 1.6 and 2.11.  It
appears the sensor or the A/D has a negative offset.  Using intensity axis,
the plot is straight down to the interception at 2.11 OD (0.78% intensity),
with a little response at 0.5% intensity (2.26 OD).  Note that 0.78% is
equivalent to step 22 on the Q60 slide, so this black clipping would be
difficult to discover with the Q60.

NikonScan 3.0 yeilded results similar to Vuescan, but NikonScan 3.1
dramatically improved shadow detail.  Using the image setting gives good
linearity to 2.56 OD, rounding off above 2.7 OD.  Using the Kodachrome
setting in NikonScan 3.1 resulted in slightly lower slope to 2.4 OD, and OD
slope of 0.4 from 2.4 to 3 OD.

Depth of field is manageable with the IV.  Cardboard mounted Kodachrome
slides show grain to the edges.  At the center, 1.4 klp/i can be seen,
while at the left corners 1.4 and 1.2 klp/i can be seen vertically and
horizontally, respectively.  At the right corners, 1.2 and 0.9 klp/i can be
seen vertically and horizontally, respectively.  At the center, the MTF is
50% at 450 lp/i.  Using a focus point midway between center and corners
give 1.4 klp/i at the center and 1.4 and 1.2 klp/i vertically and
horizontally, respectively, at the right corners.

A 400 ASA Kodak Max negative used with the SA-21 strip adapter, showed a
loss of resolution (1.35 klp/i to  1 klp/i at the edges) instead of 1.35
klp/i at the center). The FH-3 holder showed essentially no loss in
resolution at edges.  There was some faint aliasing noticed at 1.6 klp/i.
My focus-free Minolta Dual (SCSI) showed some loss at the edges and less
overall resolution (1.15 klp/i).

Mike Duncan

Mike Duncan