Aperture Diaphragm - Optika Italy B-510 Serie Manuel D'utilisation

9.10

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.
• With low contrast specimens set the numerical
aperture value ① (printed on the condenser ring)
to about 70%-80% of the objective's N.A. (Fig. 38)
If necessary, remove on eyepiece and, looking
into empty sleeve, adjust the condenser's ring in
order to obtain an image like the one in fig. 39.
Example: with objective PLAN 40x / 0,65 set the
scale to 0.65 x 0.8 = 0,52
APERTURE
DIAPHRAGM
FIELD OF VIEW
Page 18
①
F ig. 27 F ig. 27
70-80%
30-20%
F ig. 28 F ig. 28