Centering The Condenser; Effects Of The Field Diaphragm; Aperture Diaphragm - Optika Italy B-810 Serie Manuel D'instructions

9.10 Centering the condenser

1. Place the specimen on the stage, insert 10x
objective into the light path and focus.
2. Insert the front lens of the swing-out condenser
①. (Fig. 16)
3. Rotate the field
counterclockwise direction, to fully close the
diaphragm.
4. Rotate the condenser height adjustment knob ③
to focus the edges of the diaphragm.
5. Rotate the two centering screws ④ to bring the
bright spot in the center of the field of view.
6. Gradually open the diaphragm. The condenser
is centered when the diaphragm image is
symmetrical to the field of view. (Fig. 17)
7. In normal use, open the diaphragm until it
circoscribes the field of view.
9.11 Effects of the field diaphragm
Field diaphragm adjusts the illuminated area to obtain
a high contrast image.
Set the diaphragm according to the objective in
use until it circoscribes the field of view, in order to
eliminate unnecessary light to eyepieces.
9.12 Aperture diaphragm
• The Numerical Aperture (N.A.) value of the
aperture diaphragm affects the image contrast.
Increasing or reducing this value one can vary
resolution, contrast and depth of focus of the
image.
• With low contrast specimens set the numerical
aperture value ⑤ (printed on the condenser ring)
to about 70%-80% of the objective's N.A. (Fig. 18)
If necessary, remove on eyepiece and, looking
into empty sleeve, adjust the condenser's ring in
order to obtain an image like the one in fig. 19.
Example: with objective PLAN 40x / 0,65 set the
scale to 0.65 x 0.8 = 0,52
diaphragm ring
②
③
in
①
②
IRIS
DIAPHRAGM
FIELD OF VIEW
Page 15
④
Fig. 16
Fig. 17
⑤
Fig. 18
70-80%
30-20%
Fig. 40
Fig. 19