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Centring the aperture diaphragm
Turn a low to medium objective magnification
10x/20x into the light path and focus a specimen
with the coarse and fine drive.
Remove an eyepiece from one of the two
eyepiece tubes and look into the empty tube or
move the Bertrand lens into the light path.
Regulate the light intensity so that the rear
objective pupil (rear lens surface of the ob-
jective) can be clearly seen.
Using the adjustment button (72.1), open the
aperture diaphragm nearly to the edge of the
pupil.
Centre the aperture diaphragm to the edge of
the pupil with the centring screws (72.2).
The aperture diaphragm influences the reso-
lution, contrast and field depth of the micro-
scope image. Image quality greatly depends on
how carefully it is set. It may not be used for
regulating the image intensity.
Centring the field diaphragm
Turn a low to medium objective magnification
10x/20x into the light path and focus a specimen
with the coarse and fine drive.
Open the field diaphragm almost as far as the
edge of the field of view.
Using the centring buttons (72.4), centre the field
diaphragm to the edge of the field of view.
The field diaphragm is imaged on the surface of
the specimen, framing the illuminated field.
Normally, the field diaphragm is opened until it
just disappears out of the field of view.
When imaging reduced picture diagonals such
as in photomicrography or TV microscopy, the
field diaphragm can be narrowed to frame the
picture format, enhancing the image contrast.
The aperture diameter of the field diaphragm
remains the same for all objective magnifi-
cations.
Fig.␣ 72␣ ␣ Aperture and field diaphragm␣
1 Aperture diaphragm adjustment, 2 Aperture diaphragm
centring screws, 3 Field diaphragm adjustment, 4 Field
diaphragm centring screws
4
1
2
3