Optika Italy D-290TB Serie Manual De Instrucciones página 17

8.8 Condenser centering
• The condenser is installed and pre-centered in
the factory.
• To remove the condenser use an Allen wrench
1.5 mm and operate on the fixing knob placed on
the right side of the condenser holder.
Should a new centering is needed, operate in this
way:
1. Insert 4x objective in the light path (in case 4x is
not available use the lower magnification avail-
able).
2. Focus the specimen.
3. Close the aperture diaphragm using the ring ①,
moving the ring to the value "4" related to the 4x
objective. (Fig. 26)
4. Raise the condenser to the upper limit using the
height adjustment knob ② placed on the left side
of the condenser holder.
5. Center the condenser using the centering screws
③ until the field of view is evenly illuminated (in
the field of view no dark and bright areas must be
noticed).
6. Fully open the diaphragm.
8.9 Aperture diaphragm
• The Numerical Aperture (N.A.) value of the ap-
erture diaphragm affects the image contrast. In-
creasing or reducing this value one can vary res-
olution, contrast and depth of focus of the image.
Move the diaphragm ring ① (Fig. 26) on the value
corresponding to the objective in use. In this case
the optimal setting of the condenser is achieved.
• With low contrast specimens set the numerical
aperture to about 70%-80% of the objective's
N.A. If necessary, remove on eyepiece and, look-
ing into empty sleeve, adjust the condenser's
diaphragm in order to obtain an image like the
one in Fig. 27.
②
①
APERTURE
DIAPHRAGM
FIELD OF VIEW
Page 17
F F ig. 26 ig. 26
③
70-80%
30-20%
F ig. 27 F ig. 27