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7. Start-up
• Make sure that the condenser is at the
correct height. The condenser height
adjustment
lets you set the condenser head to
the height of the nominal free working
distance. (For an S23 condenser, for example,
the distance between the surface of the stage
and the front lens of the condenser is approx.
23mm).
• Hold a piece of white paper (approx. 3-10cm)
under the light source (field diaphragm).
A light ring should appear on the paper – if
not, check the power cable, the light source
and the fuse of the supply unit (CTR box) and
make sure that all of the parts are correctly
connected to one another.
• Open the field diaphragm as far as possible
until the light ring reaches its maximum
diameter.
• Next, hold the paper under the condenser,
directly on the stage. Open the aperture
diaphragm as far as possible, until the light
ring has reached its maximum brightness. In
order to achieve maximum brightness, make
sure that no port is activated. The full light
should be directed to the VIS port.
• Check the magnification changer to make
sure that the 1x tube lens is selected.
• Adjust the lenses of the eyepieces so that one
circle is visible in the eyepieces (not two!). If
you wear eye glasses, remove the antiglare
hoods from the eyepiece tubes (or fold them
back).
• Make sure that the focus on the eyepieces is
set to
±
0 (turn the upper part of the eyepiece
tubes until the silver ring is just covered).
• You should see light when looking through the
eyepieces at this point.
If the light is too bright, reduce it as required.
Remove all unneeded components from the light
path.
• Swing all filters (in the filter magazine of the
lamp housing or the filter holder of the
condenser) out of the beam path.
• Set the condenser disk to the brightfield
position.
• If your microscope is equipped for DIC:
• Remove the polarizer.
• Remove the analyzer.
• Remove the objective prism (move the
magazine to the "empty" or "brightfield"
position).
• If your microscope is equipped for
fluorescence:
• Select an empty filter position (or a filter
with low transmission in the visible range,
e.g. filter A).
Now to begin with the actual Koehler illumina-
tion:
• Place your specimen on the stage and focus
so that you can see its details as clearly as
possible. You probably will not get a perfect
image at this point, as the illumination will not
be optimal (90a).
• Next, attempt to get a
sharp image
(or at least
a part of the image at the edge) by carefully
moving the condenser up and down (90.2). Try
this with a variety of field diaphragm settings
until you get a clear, sharp image (91.b). This
may take a while!
• To
center the sharp image
, insert the
centering keys in the openings provided at
either side of the top part of the condenser
(90.1). Move the image into the center of the
field of view (91.c). Next, open the field
diaphragm until the image fills nearly the
entire field of view. The black edges of the
image should have the same distance to the
outer edge of the field of view on all sides. If
