33
8. Operation
•
Adjust the aperture diaphragm subjectively,
according to your opinion of the image.
•
In principle, you can carry out a calibration
yourself by comparing with the apertures of
different objectives.
•
You can visually compare the apertures of ob-
jective and condenser as follows:
•
Remove the eyepiece from the eyepiece
tube or use a focusing telescope and focus.
•
Open or close the aperture diaphragm just
enough for your image to be visible in the
eyepoint (= illuminated circle) of the objec-
tive. This position is considered the normal
position, i.e. condenser aperture = objective
aperture.
•
Reinsert the eyepiece.
For specimens with lower contrast, you can
close the aperture diaphragm further to make
structure elements with lower contrast more
clearly visible.
!
Caution!
The aperture diaphragm in the illumination light
path is not for setting the image brightness. Only
the rotary brightness adjustment knob or the
neutral density filter should be used for this.
!
Caution!
When you presses the head of the illumination
column down to lower position, be careful of your
hands position. No not put your hand between
the empty place.
An aperture diaphragm in the objective is nor-
mally fully opened. The reduction in image bright-
ness caused by stopping down results in:
•
Greater focus depth
•
Less cover slip sensitivity
•
Dark field impression
•
Change in contrast
Possible faults
Incorrect thickness of the cover slip or incorrect
objective. Specimen positioned with cover slip
facing upwards rather than downwards.
•
Aperture diaphragm opened or closed too far.
•
Condenser in incorrect height position.
•
Light ring switched on by mistake.
•
Optics dirty.
