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2.
Mounting the Eyepieces
For mounting, simply drop the eyepiece into the eyepiece tube.
It is
recommended to leave an eyepiece in place even when it is not in use, in
order to prevent the
entrance of dust into
the eyepiece tube. Or
put on the eyepiece
cap in place of the
eyepiece removed.The
inclined eyepiece body
tube, trinocular, bino-
cular or monocular,can
be rotated after loosen-
ing the clamp screw
(Fig. 6) for conveni-
ence in viewing from
any desired direction
without
moving
the
microscope stand. By further
releasing the clamp screw the body tube
can be removed and replaced with another type eyepiece body tube.
3.
IVIounting the Condenser
To mount the condenser, unlock the lock screw, and insert the condenser
beneath the condenser
holder as far as it will
go. Then, tighten the
lock
screw.
In this
case locate the dia-
phragm
eccentering
lever and its screw at
a proper place so as
to
facilitate
their
manipulation with one
hand (Fig. 7).
The
correct distance to re-
tain immersion oil be-
tween the lower sur-
face of the slide and
the top of condenser
is secured when the
condenser is raised to the upper limit by turning the condenser focusing
knob.
- 1 1 —
ILLUMINATION
Resolution and contrast of image are greatly affected by the method of
illumination.
1.
Condenser Iris Diaphragm and Images
Stop down the condenser iris diaphragm and slide it in the radial direc-
tion from center to edge. The farther the iris diaphragm is off-centered, the
higher becomes the contrast and resolution, which distinguish details of
object by increased and unsymmetrical shadow at the boundary of object
(Fig. 8, a, b).
(a) C e n t r a l illumination
(b) Oblique illumination
(c) Dark field illumination
When the iris diaphragm is positioned so as to let the light bundle enter into
the object at an angle o'f incidence the same as the aperture angle of the
objective the resolution reaches
maximum and twice as much as the
resolution by central illumination.
If the diaphragm is further eccentered to such an extent as not to
introduce the light bundle directly into the objective, dark field illumi-
nation will be obtained.
If the iris diaphragm is widely opened, images
by various angle illuminations are integrated. An illumination angle not
favorable for the object may be included.
In the central illumination the maximum resolution is obtained when the
opening of the iris diaphragm just corresponds to the aperture angle of
the objective.
In this case excessive outer rays to be used as dark
field illumination are cut off and flare is minimized. If the opening is made
smaller, the contrast is enhanced,
though the resolution is lowered. But
if the iris diaphragm is large enough to cover 6 0 - 7 0 % of the objective
aperture, the decrease of resolution will not be remarkable.
If the diaphragm is stopped down to minimum for admitting only very
— 1 2 —
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