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[b)
[a]
j
~
__
mm_muuum
~
..
=---------------------_
..
_----=---
Fig. 4.16 Non-flat
film
Film Incurve
Nlcht
planliegender
Film
[c)
[d]
J
~
_______
m
_____
~
-,-
1·---""-~~~~-~""""'------
I
I
[e)
[ij
Fig. 4.17 Optimizing focus
for
a section
of
non-flat
film
Mise
au pOint
optlmlsee
sur
un
film
Incurve
Fur
einen Tell
elnes
nlcht
planllegenden
Blldes
optlmlerte
Fokusslerung
[g)
Fig. 4.18 The focus
control
on the
scanner
La
mise
au pOint
sur
Ie
scanner
Die Feinfokusslerung
am
Scanner
74
Non-flat film
The
film
surface is not
necessarily
flat. It
may
be
curved
for
a
number
of reasons. If the
film
is not
flat
, the
scanner
can not
accurately
focus on the
entire
film
surface
at
the
same
ti
me
. The most common cause
of
non-flat
film
is bowing caused by heat. This often
occurs
when
slides
are
used in
slide
projectors
before
scanning. The
heat
of the projection bulb will cause
the
film
in the
slide
to bow. This is shown in Figure 4.
16
.
[a]
Non-flat
film
[b) Cross section of
slide
mount
It is
therefore
necessary
for
the
user
to
compromise
on
the focus based on the
area
of the
slide
being scanned.
If
only
a section of the
film
is scanned, it may be
possible
to
adjust
the focus to best suit the
area
of
the
film
being scanned. This is shown in Figure 4.
17
.
[c) Non-flat
film
[d) Optimized focus position
[e)
Normal
detent focus
[f]
Cross
sect
ion of
slide
mount
Glass mounts can be used to
help
flatten non-
flat
film
.
The fine focus
control
The fine focus control is located on the
front
of the
scanner
as shown in
Figure
4.
18
.
This
knob can be
easily
adjusted with the thumb. A
center
detent is
provided to
center
the
film
in the field of focus. Rotating
the knob in
either
direction
will
affect the focus.
[g) Focus control
A scan is taken in the field of
interest
at
maximum
resolution. The
result
is
displayed
in a
window
on the
screen. The
user
can see the
result
of
changing
the
focus control as the scan is taken. Refer to the manual
focusing explanation in the
driver
manual
for
the
correct
control.
4-5
Calibration
The
scanner
is self-
calibrating
. A
calibrat
ion
procedure
occurs
automatically
dur
ing
power-up
.
This
procedure
typically
takes about
thirty
seconds. It is· possible to
force a
calibration
through
software
. This
may
be
advantageous
immediately
before
an
important
scan.
Due to the patented
light
source
,
there
is no
warm
up
time
necessary
for
the
scanner
. Once the
scanner
has
performed
its
power-on
calibration
, it is ready to go.