Filter
Top Products
which will give proper eye-to-lens distance.
For
those wear eyeglasses,
eyecup should
be
screwed
in.
3.
Coarse
Focusing
The coarse adjustment
may be
eased
or
tightened
by
means
of the
adjusting
ring:
If
the
revolution
of the
coarse focusing knob
is too
loose, turn
the ad-
justing
ring counterclockwise.
Too
much tightness
may be
adjusted
by the
clockwise turning.
Never
twist
the
focusing knobs
for
this adjustment
as in the
traditional
microscope whose focusing knobs, coarse
and
fine,
are
located separate
(not coaxial). Focusing
may be
performed
as
follows: First, raise
the
microscope stage until
the
distance between
the
specimen
and the
objective becomes less longer than
the
working distance
of the
objective
to
be
used
(see
table
on p. 8),
then looking through
the
eyepiece, lower
the
stage until
the
specimen
to be
examined
is
plainly visible.
4X,
lOX, 20X, 40X and lOOX
objectives
are
parfocal
, and are
approxi-
mately
in
focus when revolved into position
one
after another,
the use
of
the
fine focusing knob only being required
for
critical focusing.
4.
Preset
Device
The right-hand focusing knob
has a
preset lever
on its
drum
(Fig. 16).
When
the
lever
is
fastened
by
turning clockwise
(as
indicated
by the
arrow
engraved besides) until
it
stops,
the
coarse focusing knobs cannot
be
turned
in
the
direction
to
drive
the
stage closer
to the
objective.
This
presetting
is
—
17--
utilized
for
quick refocusing
after
the stage
has
been lowered
and outfocused
for
changing
the
specimen
or
applying
im-
mersion oil.
The
preset device,
when fastened, prevents
at the
same
time
the danger
of
damag-
ingthe
objective front
and
slide
glass.
5.
Fine
Focusing
Manipulation
of the
fine focus-
ing
knob
is
necessary:
a.
To
obtain the sharpest image.
b.
To
transfer
the
focus from
center
to a
corner
of the
viewfield.
c.
To
focus upon
the
different layers
of a
thick specimen.
d.
To
correct
a
slight blurring which
may
take place when shifting
the
slide.
e. Tomeasure
the
thickness
of
object under examination.
The microscope
is so
designed that
one
revolution
of the
fine focusing
knob
raises
or
lowers
the
microscope stage
0.2mm.
This
permits direct
reading
on the
right-hand knob scale
up to
0.002mm
(2«). The
whole
range
of
fine movement
is
38mm;
the
same
as of
coarse focusing.
6.
Oil
Immersion
When using
lOOX
objective,
the
application
of
immersion
oil in the
minute
space (0.1mm) between
the
objective
top and the
cover
glass
is
necessary
to
attain
the
specified numerical aperture.
For
critical work
the
immersion
oil is to be
filled between
the top
lens
of the
condenser
and
the
slide
as
well
as
between
the
objective
and the
cover
glass.
Oil im-
mersion observation
is
performed
as
follows: First, using
lOX or 40X ob-
jective
(dry
system), bring
the
specimen
in
focus
and in the
center
of the
viewfield.
Set the
preset lever
by
turning clockwise.
Lower
the
micro-
scope stage
and
revolve
the
nosepiece revolver
to lOOX
objective. After
applying
a
drop
of
immersion
oil
onto
the
cover
glass, raise
the
stage
up
to
the
preset
limit.
Then, focus
up by
looking through
the
eyepiece
and
raising
carefully
the
stage
by
manipulating
the
fine focusing knob.
The
oil
immersion
lOOX
objective
is
designed
to
attain
its
critical focusing
by
about
1/3
forward rotation
of the
fine focusing knob, that
is,
bringing
the
stage about
0.08mm
closer
to the
objective from
the
parfocal position.
Air bubbles
in the
immersion
oil,
which
may
sometimes intervene
the
microscope image
and are
visible when looking into
the
microscope
tube
without
the
eyepiece,
can be
removed
by
repeating slight movement
of
the
nosepiece revolver,
by
adding
a
certain quantity
of
immersion
oil
or
by
means
of a
needle.
Remaining
stiffened
oil may
often impair
the
image. Therefore,
im-
18