Condenser Centering; Effect Of Field Diaphragm; Aperture Diaphragm - Optika Italy B-1000 Serie Bedienungsanleitung

9.12 Condenser centering

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
using the lever ①. (Fig. 30)
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 symmetri-
cal 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. 31)

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.
32). If necessary, remove one eyepiece and, lo-
oking into empty sleeve, adjust the condenser's
ring in order to obtain an image like the one in
Fig. 33.
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 20
④
Fig. 30
Fig. 31
⑤
Fig. 32
70-80%
30-20%
Fig. 40
Fig. 33