Centering With Field Diaphragm; Effects Of The Field Diaphragm; Aperture Diaphragm - Optica B-380 Serie Manual De Instrucciones

9.7.2 Centering with field diaphragm
1. Put the specimen on the stage, insert 10X objec-
tive and focus the specimen.
2. Rotate the field diaphragm ring ① to fully close
the diaphragm. (Fig. 17)
3. Rotate the height adjustment knob ② to focus the
edges of the diaphragm.
4. Rotate the centering screws ③ to bring the
diaphragm's image into the center of the field of
view.
5. Gradually open the diaphragm. The condenser is
centered when the diaphragm's image is symme-
trical to the edges of the field of view.
6. In the normal use, open the diaphragm until it cir-
cumscribes the field of view.
9.8 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 elimi-
nate unnecessary light to eyepieces. (Fig. 18)
9.9

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.
Move the diaphragm ring ① (Fig. 19) on the value
corresponding to the objective in use. In this case the
optimal setting of the condenser is achieved.
It is possible, however, move the ring to lower or hi-
gher values to adapt the observation to personal pre-
ferences.
• With low contrast specimens set the numerical
aperture to about 70%-80% of the objective's
N.A. If necessary, remove on eyepiece and, lo-
oking into empty sleeve, adjust the condenser's
diaphragm in order to obtain an image like the
one in Fig. 20.
②
①
IRIS DIAPHRAGM
FIELD OF VIEW
Page 21
③
70-80%
30-20%
①
Fig. 17
Fig. 18
Fig. 19
Fig. 20