Nexcope NE620T - Page 30

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4
START-UP AND OPERATION
4.5.2. Aperture diaphragm (condenser diaphragm)
2
1
4
5
3
7
6
70-80%
30-20%
Illustration 018: Adjustment of aperture diaphragm.
Two possible ways to adjust the aperture diaphragm (condenser diaphragm):
First possibility
• Turn the aperture diaphragm ring (1) to the same number as the objective magnification
(2).
For example 10x objective: aperture diaphragm ring position 10
Second possibility
• As an alternative, loosen the small screws (3) on the eyepiece sleeves (4) to pull out the
eyepieces (5).
Use a suitable Allen key.
• Look into the eyepiece sleeve.
• Set the aperture diaphragm image (6) to approximately 70-80 % of the diameter of the
objective pupil (7) by adjusting the aperture diaphragm ring.
The aperture diaphragm (condenser diaphragm) determines the numerical ap-
erture of the illumination system. It has an effect of adjusting image resolution
and contrast. Stopping down the aperture diaphragm increases the depth of
focus.
Each time the objective is changed, the object field size and objective aperture
and possibly the centering will change slightly, so that for optimal results, the
light field and aperture diaphragm settings must be adjusted again.