Centering The Brightfield Condenser; Effects Of The Field Diaphragm; Aperture Diaphragm - Optika Italy B-510 Série Manuel D'utilisation

10.8 Centering the brightfield condenser
ace the specimen on the stage, insert 10x
1. Pl
objective into the light path and focus.
2. Insert the front lens of the swing-out condenser
①. (Fig. 17)
3. Rotate the field diaphragm ring ② in the direction
showed by the arrow, 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.
7. In normal use, open the diaphragm until it
circoscribes the field of view.
10.9 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.

10.10 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. 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. 15.
Example: with objective PLAN 40x / 0.65 set the
scale to 0.65 x 0.8 = 0.52
①
③
IMAGE OF
APERTURE
DIAPHRAGM
FIELD OF VIEW
Page 13
④
②
Fig. 17
⑤
Fig. 18
70-80%
30-20%
Fig. 19