Centering The Condenser; Effect Of Field Diaphragm; Aperture Diaphragm - Optika Italy B-1000 Serie Manual De Instrucciones

9.12 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. 34)
3. Rotate the field diaphragm ring ② clockwise, 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 symme-
trical to the field of view.
7. In normal use, open the diaphragm until it cir-
cumscribes the field of view.
9.13 Effect of 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 circumscribes the field of view, in order to eli-
minate unnecessary light to eyepieces. (Fig. 35)

9.14 Aperture diaphragm

• The Numerical Aperture (N.A.) value of the aper-
ture diaphragm affects the image contrast. Incre-
asing or reducing this value one can vary resolu-
tion, 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.
36). If necessary, remove one eyepiece and, loo-
king into empty eyepiece sleeve, adjust the con-
denser's ring in order to obtain an image like the
one in Fig. 37.
Example: with objective PLAN 40x / 0.65 set the
scale to 0.65 x 0.8 = 0,52
③
①
②
APERTURE
DIAPHRAGM
FIELD OF VIEW
Page 23
④
Fig. 34
Fig. 35
⑤
Fig. 36
70-80%
30-20%
Fig. 40
Fig. 37