Condenser Centering; Aperture Diaphragm - Optika Italy B-290 Serie Manual De Instrucciones

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 available).
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. 29)
4. Raise the condenser to the upper limit using the height ad-
justment 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 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. Move the diaphragm ring
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, looking into empty sleeve, adjust the con-
denser's diaphragm in order to obtain an image like the one
in Fig. 30.
②
①
APERTURE
DIAPHRAGM
(Fig. 29) on
①
Page 18
③
70-80%
FIELD OF VIEW
F ig. 29 F ig. 29
30-20%
F ig. 30 F ig. 30