Nikon SC - Condenser Control and Oil Immersion

3) T o proceed to focusing, first raise the stage
to the approximate working distance of the
objective being used. Then, viewing into the
microscope, lower the stage sicwviy, until the
image is brought into sharp focus,
8 . Vertical movement of condenser
1) For general use, raise the condenser to its
upper limit.
2 ) When examining non-stained specimens, it is
preferable to lower the condenser to such an
extent that a sufficient image contrast is ob¬
tained, rather than to close the condenser
diaphragm, because it has an advantage that
the contrast and brightness do not change so
abruptly and greatly.
9. Condenser diaphragm
The condenser diaphragm is intended to adjust
its numerical aperture (N.A.) and not the bright¬
ness of illumination.
1) When closed, the condenser diaphragm will
increase the image contrast but decrease the
resolving power.
If excessively closed, it causes fringes visible
at the edge of image details.
2) Opening of the diaphragm is continuously
adjustable within a range from 2.2mm to 30
mm in diameter. For general use, it should
be stopped down to 70~80% of the nu¬
merical aperture of the objective to achieve
an appropriate image contrast. For adjust¬
ment of the diaphragm, when observing,
turn the diaphragm control ring so as to
obtain an image quality suitable for the
specimen.
10. O il-immersion observation (Fig, 21)
When using the 100X objective marked with a
black ring, the specimen should be immersed in
oil by applying Nikon immersion oil between the
coverglass and the front lens of the objective.
Fig. 22
1) Using a 10X or 40X objective focus on the
specimen. Bring the desired detail in the
specimen to the center of the field of view.
2) Turning the revolving nosepiece, place the
100 X objective in a position where it is con¬
venient to apply oil. Then, tilt the oil con¬
tainer, until oil enters the nozzle. Depressing
the container, attach an appropriate amount
of oil onto the coverglass. (Fig. 221 The oil
may take in air bubbles. If any air bubble is
seen, clear off the oil using lens tissue, and
apply the oil once again.
31 Thereafter, keeping the container depressed,
apply the oil on the top end of the nozzle
to that of the objective. Then, rotate the
100X objective into the optical path.
4) If air bubbles enter the oil layer, a poor
image will result. To remove the air bubbles,
turn the revolving nosepiece several times
laterally or apply an additional drop of oil.
5) If a higher resolving power is desired, also
apply oil between the bottom of the glass
slide and the condenser top lens.
Note: For cleaning the oil, after finishing oil-
immersion observation, wipe it off
thoroughly with lens tissue.
11. M oving the glass slide
The lateral travel range of the glass slide by
means of the smaller knob on the mechanical
stage is 76mm (2.99 in), and the back and forth
travel range by means of the larger knob, 38mm
(1.5 in).
10