Centering The Condenser; Effect Of Field Diaphragm; Aperture Diaphragm - Optika B-1000 Series Instruction Manual

10.12 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. 30)
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 symmetrical to the field of view.
7. In normal use, open the diaphragm until it circumscribes the
field of view.
10.13 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 cir-
cumscribes the field of view, in order to eliminate unnecessary
light to eyepieces. (Fig. 31)

10.14 Aperture diaphragm

• The Numerical Aperture (N.A.) value of the aperture dia-
phragm affects the image contrast. Increasing or reducing
this value one can vary resolution, contrast and depth of fo-
cus of the image
• With low contrast specimens set the numerical aperture val-
ue ⑤ (printed on the condenser ring) to about 70%-80% of
the objective's N.A. (Fig. 32). If necessary, remove one eye-
piece and, looking into empty eyepiece 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
②
APERTURE
DIAPHRAGM
FIELD OF VIEW
Page 21
④
①
70-80%
F ig. 30 F ig. 30
F ig. 31 F ig. 31
⑤
F ig. 32 F ig. 32
30-20%
F F ig. 40 ig. 40
F F ig. 33 ig. 33